I'm working on my old Ampex 4460 reel to reel machine. (work is slow), and I'd like to listen to some of my old tapes. I cleaned and lubricated it, demagnetized the heads and put a tape of some familiar music on, and I thought it seemed a bit slow. So I repeated it with other tapes and then followed with an Ampex frequency response alignment tape. The scope was calibrated to 1.0ms off the 1KHZ square wave output and then I looked at the the 1KHZ sine wave off the tape. The period was approximately 1.40ms which appears to translate to 714HZ. Truly hard to believe that it's running that slow, but I don't think that the equipment is lying.

So I next got out the Strobeotac and put it on the motor capstan. The motor is rated for 1850 RPM at 115V, and it's running rock solid at 1795. I tried loading it while watching the speed and it remains steady, so it doesn't appear to be a load problem. Could such a slight motor speed reduction cause a 25 percent reduction in the frequency of my 1KHZ test tone off the tape? It doesn't seem possible, but I don't know.

The motor has a label that reads that it uses a 3.0UF 330V capacitor. I haven't investigated this yet, but with four wires going into it I figure that the cap must be on the chassis somewhere. I wouldn't think that a cap problem though would cause my RPM's to drop 55RPM would it? Oh and I have no service manual, however I don't think that service manual would do me much good with this problem anyway.


If anyone has any thoughts on this I'd sure appreciate hearing them. Thanks, Lenny

On 17/12/2014 05:53, wrote:
I'm working on my old Ampex 4460 reel to reel machine. (work is slow), and I'd like to listen to some of my old tapes. I cleaned and lubricated it, demagnetized the heads and put a tape of some familiar music on, and I thought it seemed a bit slow. So I repeated it with other tapes and then followed with an Ampex frequency response alignment tape. The scope was calibrated to 1.0ms off the 1KHZ square wave output and then I looked at the the 1KHZ sine wave off the tape. The period was approximately 1.40ms which appears to translate to 714HZ. Truly hard to believe that it's running that slow, but I don't think that the equipment is lying.

So I next got out the Strobeotac and put it on the motor capstan. The motor is rated for 1850 RPM at 115V, and it's running rock solid at 1795. I tried loading it while watching the speed and it remains steady, so it doesn't appear to be a load problem. Could such a slight motor speed reduction cause a 25 percent reduction in the frequency of my 1KHZ test tone off the tape? It doesn't seem possible, but I don't know.

The motor has a label that reads that it uses a 3.0UF 330V capacitor. I haven't investigated this yet, but with four wires going into it I figure that the cap must be on the chassis somewhere. I wouldn't think that a cap problem though would cause my RPM's to drop 55RPM would it? Oh and I have no service manual, however I don't think that service manual would do me much good with this problem anyway.


If anyone has any thoughts on this I'd sure appreciate hearing them. Thanks, Lenny


What gives the speed change? conical/stepped jockey assembly out of
registration?

Perhaps a tyre cracked and fallen off , but running against the pulley
itself now.

The motor is running 3% slow, not 25%. So the problem has to be somewhere
between the motor and the capstan.

On Wednesday, December 17, 2014 12:53:27 AM UTC-5, wrote:
I'm working on my old Ampex 4460 reel to reel machine. (work is slow), and I'd like to listen to some of my old tapes. I cleaned and lubricated it, demagnetized the heads and put a tape of some familiar music on, and I thought it seemed a bit slow. So I repeated it with other tapes and then followed with an Ampex frequency response alignment tape. The scope was calibrated to 1.0ms off the 1KHZ square wave output and then I looked at the the 1KHZ sine wave off the tape. The period was approximately 1.40ms which appears to translate to 714HZ. Truly hard to believe that it's running that slow, but I don't think that the equipment is lying.

So I next got out the Strobeotac and put it on the motor capstan. The motor is rated for 1850 RPM at 115V, and it's running rock solid at 1795. I tried loading it while watching the speed and it remains steady, so it doesn't appear to be a load problem. Could such a slight motor speed reduction cause a 25 percent reduction in the frequency of my 1KHZ test tone off the tape? It doesn't seem possible, but I don't know.

The motor has a label that reads that it uses a 3.0UF 330V capacitor. I haven't investigated this yet, but with four wires going into it I figure that the cap must be on the chassis somewhere. I wouldn't think that a cap problem though would cause my RPM's to drop 55RPM would it? Oh and I have no service manual, however I don't think that service manual would do me much good with this problem anyway.


If anyone has any thoughts on this I'd sure appreciate hearing them. Thanks, Lenny

Well I'm afraid that I misstated something. The Strobotac was actually aimed at the motor pulley, not the capstan. The speed reading that I got of 1795 RPM was in fact the motor pulley speed. The capstan of course would be spinning much slower.

So William, you mentioned 3 percent. I'm assuming that's 3 percent of 1850? Are you thinking that if I could bring my speed up 3 percent my sine wave would in fact then occupy a 1.0ms. period? And how would you increase the speed of a synchronous motor? Lenny

On Wed, 17 Dec 2014 08:46:01 -0800, captainvideo462009 wrote:

Well I'm afraid that I misstated something. The Strobotac was actually
aimed at the motor pulley, not the capstan. The speed reading that I got
of 1795 RPM was in fact the motor pulley speed. The capstan of course
would be spinning much slower.

So William, you mentioned 3 percent. I'm assuming that's 3 percent of
1850? Are you thinking that if I could bring my speed up 3 percent my
sine wave would in fact then occupy a 1.0ms. period? And how would you
increase the speed of a synchronous motor? Lenny

I don't remember working on reel-to-reel decks. But have a couple of
thoughts. Is this a (clean?) belt drive between motor and capstan? Was the
"load" test with the motor or capstan being braked? Does the capstan have
to turn the full spool and does it rotate freely? Does helping manually
make any difference?

Mike.

On Wednesday, December 17, 2014 12:53:27 AM UTC-5, wrote:
I'm working on my old Ampex 4460 reel to reel machine. (work is slow), and I'd like to listen to some of my old tapes. I cleaned and lubricated it, demagnetized the heads and put a tape of some familiar music on, and I thought it seemed a bit slow. So I repeated it with other tapes and then followed with an Ampex frequency response alignment tape. The scope was calibrated to 1.0ms off the 1KHZ square wave output and then I looked at the the 1KHZ sine wave off the tape. The period was approximately 1.40ms which appears to translate to 714HZ. Truly hard to believe that it's running that slow, but I don't think that the equipment is lying.

So I next got out the Strobeotac and put it on the motor capstan. The motor is rated for 1850 RPM at 115V, and it's running rock solid at 1795. I tried loading it while watching the speed and it remains steady, so it doesn't appear to be a load problem. Could such a slight motor speed reduction cause a 25 percent reduction in the frequency of my 1KHZ test tone off the tape? It doesn't seem possible, but I don't know.

The motor has a label that reads that it uses a 3.0UF 330V capacitor. I haven't investigated this yet, but with four wires going into it I figure that the cap must be on the chassis somewhere. I wouldn't think that a cap problem though would cause my RPM's to drop 55RPM would it? Oh and I have no service manual, however I don't think that service manual would do me much good with this problem anyway.


If anyone has any thoughts on this I'd sure appreciate hearing them. Thanks, Lenny

To answer your questions Mike yes there is a flat belt from motor pulley to capstan flywheel, (see further explanation on that below). The load test on the motor was putting a drag on it with my finger as it was turning. It had no trouble maintaining speed as observed with the strobe tach. i don't understand what you mean when you ask if the capstan has to turn the "full spool". As far as helping manually there really is no way to help manually other than by decreasing the hold back tension. I tried that too but it didn't make much difference. What follows is some further information.

One other thing that I didn't mention was the the main drive belt. It is a flat belt which is roughly 2.0mm thick and has a circumference of approximately 35cm. The other belts are basically just different sized O rings which only needed the slick stripped off of them to expose some good grippy rubber. I had to do that with the capstan pinch roller as well. I used a bit of lacquer thinner on the belts and sand paper and thinner on the roller too to get to some good rubber

The OEM flat belt though was very tired and had "assumed the position" of an oval from sitting in one position unused for so long. I couldn't find anything around here having that circumference that was 2.0 mm thick so as a temporary measure I substituted a much thinner belt. There is a very slight amount of wow which can be seen when looking at the capstan flywheel with the strobe using this substitute belt, and I'm guessing that it could be stretching back and forth ever so slightly as it spins, but you really don't notice it on music and it's only temporary until I can find something a little more appropriate. I wouldn't think that a thinner belt would contribute to a speed error, or am I wrong in making that assumption? Lenny

On Wed, 17 Dec 2014 10:18:41 -0800 (PST),
wrote:

On Wednesday, December 17, 2014 12:53:27 AM UTC-5, wrote:
I'm working on my old Ampex 4460 reel to reel machine. (work is slow), and I'd like to listen to some of my old tapes. I cleaned and lubricated it, demagnetized the heads and put a tape of some familiar music on, and I thought it seemed a bit slow. So I repeated it with other tapes and then followed with an Ampex frequency response alignment tape. The scope was calibrated to 1.0ms off the 1KHZ square wave output and then I looked at the the 1KHZ sine wave off the tape. The period was approximately 1.40ms which appears to translate to 714HZ. Truly hard to believe that it's running that slow, but I don't think that the equipment is lying.

So I next got out the Strobeotac and put it on the motor capstan. The motor is rated for 1850 RPM at 115V, and it's running rock solid at 1795. I tried loading it while watching the speed and it remains steady, so it doesn't appear to be a load problem. Could such a slight motor speed reduction cause a 25 percent reduction in the frequency of my 1KHZ test tone off the tape? It doesn't seem possible, but I don't know.

The motor has a label that reads that it uses a 3.0UF 330V capacitor. I haven't investigated this yet, but with four wires going into it I figure that the cap must be on the chassis somewhere. I wouldn't think that a cap problem though would cause my RPM's to drop 55RPM would it? Oh and I have no service manual, however I don't think that service manual would do me much good with this problem anyway.


If anyone has any thoughts on this I'd sure appreciate hearing them. Thanks, Lenny

To answer your questions Mike yes there is a flat belt from motor pulley to capstan flywheel, (see further explanation on that below). The load test on the motor was putting a drag on it with my finger as it was turning. It had no trouble maintaining speed as observed with the strobe tach. i don't understand what you mean when you ask if the capstan has to turn the "full spool". As far as helping manually there really is no way to help manually other than by decreasing the hold back tension. I tried that too but it didn't make much difference. What follows is some further information.

One other thing that I didn't mention was the the main drive belt. It is a flat belt which is roughly 2.0mm thick and has a circumference of approximately 35cm. The other belts are basically just different sized O rings which only needed the slick stripped off of them to expose some good grippy rubber. I had to do that with the capstan pinch roller as well. I used a bit of lacquer thinner on the belts and sand paper and thinner on the roller too to get to some good rubber

The OEM flat belt though was very tired and had "assumed the position" of an oval from sitting in one position unused for so long. I couldn't find anything around here having that circumference that was 2.0 mm thick so as a temporary measure I substituted a much thinner belt. There is a very slight amount of wow which can be seen when looking at the capstan flywheel with the strobe using this substitute belt, and I'm guessing that it could be stretching back and forth ever so slightly as it spins, but you really don't notice it on music and it's only temporary until I can find something a little more appropriate. I wouldn't think that a thinner belt would contribute to a speed error, or am I wrong in making that assumption? Lenny


Lenny,

About 12 years ago I had a Crown R to R that would not play tapes at
the correct speed and it turned out to be the motor. I had lubed the
bearings and there was very little rotational resistance but still the
speed was incorrect. I got a rebuilt motor from a former Crown
employee and the speed was spot on. I never found out what caused the
problem. Chuck

On Wednesday, December 17, 2014 12:53:27 AM UTC-5, wrote:
I'm working on my old Ampex 4460 reel to reel machine. (work is slow), and I'd like to listen to some of my old tapes. I cleaned and lubricated it, demagnetized the heads and put a tape of some familiar music on, and I thought it seemed a bit slow. So I repeated it with other tapes and then followed with an Ampex frequency response alignment tape. The scope was calibrated to 1.0ms off the 1KHZ square wave output and then I looked at the the 1KHZ sine wave off the tape. The period was approximately 1.40ms which appears to translate to 714HZ. Truly hard to believe that it's running that slow, but I don't think that the equipment is lying.

So I next got out the Strobeotac and put it on the motor capstan. The motor is rated for 1850 RPM at 115V, and it's running rock solid at 1795. I tried loading it while watching the speed and it remains steady, so it doesn't appear to be a load problem. Could such a slight motor speed reduction cause a 25 percent reduction in the frequency of my 1KHZ test tone off the tape? It doesn't seem possible, but I don't know.

The motor has a label that reads that it uses a 3.0UF 330V capacitor. I haven't investigated this yet, but with four wires going into it I figure that the cap must be on the chassis somewhere. I wouldn't think that a cap problem though would cause my RPM's to drop 55RPM would it? Oh and I have no service manual, however I don't think that service manual would do me much good with this problem anyway.


If anyone has any thoughts on this I'd sure appreciate hearing them. Thanks, Lenny

I'm thinking along those lines too but do you think that 55RPM slow would cause such a drastic slowdown on playback? Here is another interesting observation. I have a another similar Ampex junker in the shop. It is a different model but a similar chassis. The motor is a 2 wire job from a different contractor and apparently with no external capacitor. The motor pulley, capstan, flywheel, etc all look the same. I had considered trying to swap motors but decided to do a speed test on the other one first. It spins up at 1680 RPM. So either there are different sized parts in that chassis, or that motor is bad too. Lenny

On 12/17/2014 10:18 AM, wrote:

The OEM flat belt though was very tired and had "assumed the
position"
of an oval from sitting in one position unused for so long. I
couldn't find anything around here having that circumference that was
2.0 mm thick so as a temporary measure I substituted a much thinner
belt. There is a very slight amount of wow which can be seen when
looking at the capstan flywheel with the strobe using this substitute
belt, and I'm guessing that it could be stretching back and forth
ever so slightly as it spins, but you really don't notice it on music
and it's only temporary until I can find something a little more
appropriate. I wouldn't think that a thinner belt would contribute to
a speed error, or am I wrong in making that assumption? Lenny

I would put the correct belt on there before getting into other minutia,
otherwise you may just end up chasing your tail.

wrote:


If anyone has any thoughts on this I'd sure appreciate hearing them.

I have one stupid idea, is there a switch somewhere on the rear panel for
changing the line cycles from 50hz to 60hz?

I remember some older Akai decks (1710/20/30 come to mind) has this along
with a mechanical voltage selector for the unit, from 100vac to 220.

I just seem to remember if the 50/60hz switch was wrong, there was a speed
problem with the capstan motor, although I think it was along the lines of
running fast (switch on 50hz when you are feeding in 120v/60hz).

There is a fairly large ratio on the capstan, figuring the diameter that
goes against the pinch roller is 1/4" or less and the flywheel part was 5
or 6 inches (at least), it's like 25:1 or 30:1.

Everything seems to point to the belt, because that usually is all that is
there between the motor and flywheel but I've see broken belts, belts with
flat spots, belts that turned into glue but none of them from memory that
would cause a constant 25% loss of rpm. No rotation or really bad wow and
flutter.

I'm guessing if it'a "universal hysteresis" motor and the machine was
designed for 100v to 220v without adapters, it's in the voltage or cycle
selection somehow.

It might even be a mechanical adjustment. Just occured to me the earlier
AKAI units had like a screw driver slot to change the motor speed via tossing
it on a different pully off the motor. The hole was marked 50/60hz.

If the shaft has a dual pulley, might just be on the wrong one.

-bruce

On Wednesday, December 17, 2014 12:53:27 AM UTC-5, wrote:
I'm working on my old Ampex 4460 reel to reel machine. (work is slow), and I'd like to listen to some of my old tapes. I cleaned and lubricated it, demagnetized the heads and put a tape of some familiar music on, and I thought it seemed a bit slow. So I repeated it with other tapes and then followed with an Ampex frequency response alignment tape. The scope was calibrated to 1.0ms off the 1KHZ square wave output and then I looked at the the 1KHZ sine wave off the tape. The period was approximately 1.40ms which appears to translate to 714HZ. Truly hard to believe that it's running that slow, but I don't think that the equipment is lying.

So I next got out the Strobeotac and put it on the motor capstan. The motor is rated for 1850 RPM at 115V, and it's running rock solid at 1795. I tried loading it while watching the speed and it remains steady, so it doesn't appear to be a load problem. Could such a slight motor speed reduction cause a 25 percent reduction in the frequency of my 1KHZ test tone off the tape? It doesn't seem possible, but I don't know.

The motor has a label that reads that it uses a 3.0UF 330V capacitor. I haven't investigated this yet, but with four wires going into it I figure that the cap must be on the chassis somewhere. I wouldn't think that a cap problem though would cause my RPM's to drop 55RPM would it? Oh and I have no service manual, however I don't think that service manual would do me much good with this problem anyway.


If anyone has any thoughts on this I'd sure appreciate hearing them. Thanks, Lenny

Those are some great ideas Bruce but I think I've been down that whole road already. The machine is definitely from the US market only, that is 115V 60 cyc marked. Yesterday I tried putting a small AC cap in parallel with the original 3uf cap. It made the motor hum and slowed it down. Today I'll try decreasing the capacitance slightly and see what happens. I'm running out of tricks though. I still have to wonder though would a 55RPM drop in motor speed cause the degree of speed problem I'm seeing on the tape? Lenny

wrote in message ...

Those are some great ideas Bruce but I think I've been down that whole road
already. The machine is definitely from the US market only, that is 115V
60Hz
marked. Yesterday I tried putting a small AC cap in parallel with the
original
3uf cap. It made the motor hum and slowed it down. Today I'll try decreasing
the capacitance slightly and see what happens. I'm running out of tricks
though.
I still have to wonder though would a 55RPM drop in motor speed cause the
degree of speed problem I'm seeing on the tape? Lenny

As I pointed out, it's a 3% change. Gears and pulleys work on ratios, not
absolute values. The motor appears to be basically "on speed", so the problem
has to be somewhere else.

This is not a personal remark, just a statement of what I see as fact. It
appears that you don't understand much about mechanical systems. You need to
find someone who feels comfortable with them, and have him take a look,

Well that clears up a couple questions I was going to ask. If you are our Lenny, I thought you were in the US but really never knew it for sure. Never gave it a thought.

However, looking at the responses I see a few things. for one, the 50/60 Hz sitch or whatver, if wrong would make it run fast. Having worked on this kind of **** I say the following :

First, when you measure the RPM of the motor, is that with the belts etc. disconnected ?

With everything disconnected, does the shaft turn freely ? If you just give it a flick it should keep turning from its own momentum.

Same is true of the flywheel and capstan.

Belts typically lose a few RPM here and there, alost always. that is why there are TEETH on the timing belt in cars. Of course teeth here would cause flutter. Capstan bearings can get sticky. What's more alot of them wear out and then the capstan is not held at the correct angle. If you have a bearing problem I could actusally make one if I can get the brass stock, but there is a workaround. the bearing is usually screwed to the main chassis2 by three screws. Most of the tiome you can rotate the bearing and the capastan will align because all the pressure is against fresh parts of the surface. Of course it is possible that this has already been done if you are not the original purchaser.

So get everything disconnected and turn things freehand. Also, with the belt off, engage the pinch roller. It should not cause all that much drag. If so, you might have a groove worn into the capstan bearing.

Actually I should call it a bushing, they are usually brass. I have never seen one with ball bearings.

Sometimes you can tell if the bushings are worn by the behavior of the tape as it goes through. you, I think you would have noticed that but it can also be insidious. It all depends on the architecture of the machine. there is a force applied by the pinch roller, and there is a force applied by the belt or idler. These cause a certain wear pattern. This varies of course because of whatever angle the belt or pulley comes from, but of course the force from the pinch roller is always perpendicular to the tape path, or close.

If you don't figure this out soon I will see if maybe hifiengine has rthe manual for it and give it a look. It sounds like you will figure it out but you need to get back to basic mechanics.

Incidentally, I THINK (not totally sure) that if the cap starts going bad on a cap run motor it will still turn about the same RPMs but pull more current. that fact that irt is a little low means maybe the cap is really bad and the load is pulling it out of synchronicity. So it matters if you check it under load or not, and actually to see if there is a major difference.

We had a discussion about that on one of the sci dot whatevers a couple years ago about replacing the capacitors in people's central AC units, that is could save them money. Years ago my Mother's house was hot in the summer because it was so damn expensive to run the air. Then it quit completely. Atr I threw in a run cap it was alot cheaper to run. But the thing is that it seems like these things just run at the right RPMs until theyu do not run at all, IN THAT APPLICATION.

Friggin R2Rs, why the cap ? And change the cap for 50 Hz and all that ****. why didn't thwey just use a brushless slotless DC motor ?

Oh yeah. Oldness. I can feel it.

On Wednesday, December 17, 2014 12:53:27 AM UTC-5, wrote:
I'm working on my old Ampex 4460 reel to reel machine. (work is slow), and I'd like to listen to some of my old tapes. I cleaned and lubricated it, demagnetized the heads and put a tape of some familiar music on, and I thought it seemed a bit slow. So I repeated it with other tapes and then followed with an Ampex frequency response alignment tape. The scope was calibrated to 1.0ms off the 1KHZ square wave output and then I looked at the the 1KHZ sine wave off the tape. The period was approximately 1.40ms which appears to translate to 714HZ. Truly hard to believe that it's running that slow, but I don't think that the equipment is lying.

So I next got out the Strobeotac and put it on the motor capstan. The motor is rated for 1850 RPM at 115V, and it's running rock solid at 1795. I tried loading it while watching the speed and it remains steady, so it doesn't appear to be a load problem. Could such a slight motor speed reduction cause a 25 percent reduction in the frequency of my 1KHZ test tone off the tape? It doesn't seem possible, but I don't know.

The motor has a label that reads that it uses a 3.0UF 330V capacitor. I haven't investigated this yet, but with four wires going into it I figure that the cap must be on the chassis somewhere. I wouldn't think that a cap problem though would cause my RPM's to drop 55RPM would it? Oh and I have no service manual, however I don't think that service manual would do me much good with this problem anyway.


If anyone has any thoughts on this I'd sure appreciate hearing them. Thanks, Lenny

In the early 1970's I was the service manager for a broadcast and recording equipment company. I worked on a lot of Ampex, Scully, Revox, etc. professional machines. This unit, the F4460 although an Ampex was built for the consumer market. and although the electronics was superb, just about up to par with the professional machines, the transport however left a lot to be desired.

To keep the costs down, (under a grand at the time, I think) they had to chinch on something, and it was the deck. The studio machines employed three motors. There was a main, and also a take up, and a hold back motor. These two torque motors would not spin during normal operation but were used to maintain proper tape tension on the heads.

Ampex had a few of these consumer type machines on the market at the time that used similar other cheaper techniques to try to accomplish the same thing as the pro machines. For instance Instead of a take up torque motor there was a slipping clutch on the take up pulley. And for hold back tension, instead of a motor tensioning the tape across the heads a felt washer jammed the tape against a guide on the left side of the machine. This washer would eventually load up with tape material, the transport would start wowing and the washer would have to be removed, cleaned with alcohol and reinstalled. A pain in the ass but worth it to have an Ampex.

I didn't ever really recall ever having a speed problem like I'm having with mine with one of these consumer type machines, or even ever having to check speed as referenced from an alignment tape as I did here with the scope. They just always seemed to be on speed.

So Jurb to answer some of your questions, or suggestions, yes I am in the US, New Hampshire to be exact. We haven't seceded from the Union yet, although sometimes I wish we would. I tried checking RPM both ways; unloaded and then loaded with belts capstan engaged, and then "overloaded" (the finger on the pulley test). And through it all the motor maintained constant torque and speed. Both the motor and flywheel turn freely. The motor actually has two fill holes for each bushing. I was able to stick a hypo filled with 10W into each hole and hit what seemed like a felt sponge around an oilite bearing. Besides if either one of these items was stiff I would expect to see a speed fluctuation problem, which I don't. The capstan bushing is also tight. Other than that I can add that this machine had a very easy life before I acquired it. It was hardly used at all. Tomorrow I'll play with the cap value and see what happens.

Really thought this thing would be off my bench by now, and back in the entertainment center and I'd be listening to my Grateful Dead tapes. ****en bummer. Lenny

**** Lenny I am way cooler than you, or was...

I had me a Viking Of Mineapolis. It was not only tube, the optional record amplifiers could be removed, unplugged. Whether yuo bought into the record capability was irrelevant however, to the playback. All you needee was a preamp the had tape (NARTB equalized) inputs. Just so happens I had one, and for the life of me I can't reme,mber the make and model of it. It MAYT have been an H.H. Scott but don't take that to the usury.... er .. bank.

Anyway, to get back to your dilemma. At this point I suspect your tachometer. That ia not a large error. Hoever this does not explain the much larger error in the actual tape speed.

Here is something interesting just occurred to me, you know tape does not shrink. Is it possible that the slight error in motor speed combined with the tape being stretched has resulted in the cumulative error you obseved ?

Really, 700 some Hz is way off of 1,000. You can REALLY hear that. You said it sounded slow, I guess it was. But why.

Ihave ****ed with a couple of reel to reels laely and I see the tape is not what it once was, n fact me and my little crew have zero good tape. The best **** we got right now clogs up theheadss in like, half hour or something.. It still plays but the level keeps dropping. I looked at the prices of new tape and decided, not.

These are really cool. When I hit the lottery I will send a minion to pick me one up... I have digital solution anyway, but I still think they're cool.. In fact my buddy has a nice Teac he is probaably going to sell. I worked on it, it is a fucink nice deck, really. Takes the 10" reels. Four track simulcord. Though it is a three head, it can switch the playback head to the record head in sound on sound to keep the sound in sync. Otherwise yoy owuld have to waste a generation on every overdub. Or whatever. Ask Les Paul lol. you know whatI mean. The thing is a practical recording studio.

I oculd not get nfo on your Ampex from the usual sources. I did however score in the 99th percentile in mechanical reasoning in one of them thar pre SAT typee thingies when I was young. I mean before I crashed a car young, and that means young. All those idlers and ****, unless ther eis a driven shaft rubber wheel (whiich is not an idler) or some type of stepped thing, the size does not really matter.

An idler by definition is not driven by its shaft. If it is, it is a drive wheel, not an idler.

For example, on a record player if you were to make the idler wheel a bit bigger, the speed would not change except for maybe what the rubber drags it down or something. Ther math has not changed because the only numbers tha tmatter are those of the SFM of the motor shaft and the SFM of the driven flywheel which is either the tunrtable or the alumin(i)um thing attched to the capstan. Math it math.

It is usual to have that much of a speed error on something like that, but of course that explins your presence here...

Anyway, the way I see it is suspect the RPM meter about the motor, OR maybe those extra wires go to the cap to trim the speed. (???) Now that would be tripped out. But tell you what, it is very possible.

Look see if there is any rubber in that thing that is nailed down. By that I mean a driven shaft with a rubber surface driving something. There is a good reason they stuck with the metal motor shaft and the final dirven thing, those two diaameters make the ratio and that is that. Other designs not so much.

hell, you might have to rewire the capacitor to give more RPMs. Seriously, that is possible.

Wish ?I oculd get a mmanual ion that thing, dammit

"It is usual to have that much ..."

Of course I meaant unusual but forgot the un part.

Have an uncola.

On 19.12.14 4:16, wrote:
On Wednesday, December 17, 2014 12:53:27 AM UTC-5, wrote:
I'm working on my old Ampex 4460 reel to reel machine. (work is slow), and I'd like to listen to some of my old tapes. I cleaned and lubricated it, demagnetized the heads and put a tape of some familiar music on, and I thought it seemed a bit slow. So I repeated it with other tapes and then followed with an Ampex frequency response alignment tape. The scope was calibrated to 1.0ms off the 1KHZ square wave output and then I looked at the the 1KHZ sine wave off the tape. The period was approximately 1.40ms which appears to translate to 714HZ. Truly hard to believe that it's running that slow, but I don't think that the equipment is lying.

So I next got out the Strobeotac and put it on the motor capstan. The motor is rated for 1850 RPM at 115V, and it's running rock solid at 1795. I tried loading it while watching the speed and it remains steady, so it doesn't appear to be a load problem. Could such a slight motor speed reduction cause a 25 percent reduction in the frequency of my 1KHZ test tone off the tape? It doesn't seem possible, but I don't know.

The motor has a label that reads that it uses a 3.0UF 330V capacitor. I haven't investigated this yet, but with four wires going into it I figure that the cap must be on the chassis somewhere. I wouldn't think that a cap problem though would cause my RPM's to drop 55RPM would it? Oh and I have no service manual, however I don't think that service manual would do me much good with this problem anyway.


If anyone has any thoughts on this I'd sure appreciate hearing them. Thanks, Lenny

In the early 1970's I was the service manager for a broadcast and recording equipment company. I worked on a lot of Ampex, Scully, Revox, etc. professional machines. This unit, the F4460 although an Ampex was built for the consumer market. and although the electronics was superb, just about up to par with the professional machines, the transport however left a lot to be desired.

To keep the costs down, (under a grand at the time, I think) they had to chinch on something, and it was the deck. The studio machines employed three motors. There was a main, and also a take up, and a hold back motor. These two torque motors would not spin during normal operation but were used to maintain proper tape tension on the heads.

Ampex had a few of these consumer type machines on the market at the time that used similar other cheaper techniques to try to accomplish the same thing as the pro machines. For instance Instead of a take up torque motor there was a slipping clutch on the take up pulley. And for hold back tension, instead of a motor tensioning the tape across the heads a felt washer jammed the tape against a guide on the left side of the machine. This washer would eventually load up with tape material, the transport would start wowing and the washer would have to be removed, cleaned with alcohol and reinstalled. A pain in the ass but worth it to have an Ampex.

I didn't ever really recall ever having a speed problem like I'm having with mine with one of these consumer type machines, or even ever having to check speed as referenced from an alignment tape as I did here with the scope. They just always seemed to be on speed.

So Jurb to answer some of your questions, or suggestions, yes I am in the US, New Hampshire to be exact. We haven't seceded from the Union yet, although sometimes I wish we would. I tried checking RPM both ways; unloaded and then loaded with belts capstan engaged, and then "overloaded" (the finger on the pulley test). And through it all the motor maintained constant torque and speed. Both the motor and flywheel turn freely. The motor actually has two fill holes for each bushing. I was able to stick a hypo filled with 10W into each hole and hit what seemed like a felt sponge around an oilite bearing. Besides if either one of these items was stiff I would expect to see a speed fluctuation problem, which I don't. The capstan bushing is also tight. Other than that I can add that this machine had a very easy life before I acquired it. It was hardly used at all. Tomorrow I'll play with the cap value and see what happens.

Really thought this thing would be off my bench by now, and back in the entertainment center and I'd be listening to my Grateful Dead tapes. ****en bummer. Lenny

Maybe a silly suggestion, but check your scope 1khz signal.
Because those are not very reliable signal sources, specially
in old scopes. The square wave is usually oke, but the frequency
might be off. Maybe your voltmeter has a frequency measurement range.

Sjouke Burry wrote:



Maybe a silly suggestion, but check your scope 1khz signal.
Because those are not very reliable signal sources, specially
in old scopes. The square wave is usually oke, but the frequency
might be off. Maybe your voltmeter has a frequency measurement range.


** That might be the case OR the capstan roller has gone smooth and hard with age and is failing to control the speed of the tape through the capstan gate.

With this sort of defect, tape speed can increase or decrease, depending
whether the take up reel or supply reel has more torque. A simple test is to see if it is easy to pull tape through the capstan gate with the machine turned off - if it is, you have a problem.

Having serviced many Roland tape echo machines made back in the 1980s (the famous Space Echo and Chorus Echo models ) I can say the one fault common to practically ALL examples seen is a shiny, smooth pinch roller.

Since no new supply of suitable rollers exists, I fit the old one with a suitable shaft and lock it into the chuck of a bench drill spinning at 600rpm - then, using finger pressure on a piece of fine sand paper wrapped around strip of wood, gently remove the shiny surface & restore the needed matt one.


.... Phil

"Sjouke Burry" wrote in message
...
On 19.12.14 4:16, wrote:
On Wednesday, December 17, 2014 12:53:27 AM UTC-5,
wrote:
I'm working on my old Ampex 4460 reel to reel machine. (work is slow),
and I'd like to listen to some of my old tapes. I cleaned and lubricated
it, demagnetized the heads and put a tape of some familiar music on, and
I thought it seemed a bit slow. So I repeated it with other tapes and
then followed with an Ampex frequency response alignment tape. The scope
was calibrated to 1.0ms off the 1KHZ square wave output and then I
looked at the the 1KHZ sine wave off the tape. The period was
approximately 1.40ms which appears to translate to 714HZ. Truly hard to
believe that it's running that slow, but I don't think that the
equipment is lying.

So I next got out the Strobeotac and put it on the motor capstan. The
motor is rated for 1850 RPM at 115V, and it's running rock solid at
1795. I tried loading it while watching the speed and it remains steady,
so it doesn't appear to be a load problem. Could such a slight motor
speed reduction cause a 25 percent reduction in the frequency of my 1KHZ
test tone off the tape? It doesn't seem possible, but I don't know.

The motor has a label that reads that it uses a 3.0UF 330V capacitor. I
haven't investigated this yet, but with four wires going into it I
figure that the cap must be on the chassis somewhere. I wouldn't think
that a cap problem though would cause my RPM's to drop 55RPM would it?
Oh and I have no service manual, however I don't think that service
manual would do me much good with this problem anyway.


If anyone has any thoughts on this I'd sure appreciate hearing them.
Thanks, Lenny

In the early 1970's I was the service manager for a broadcast and
recording equipment company. I worked on a lot of Ampex, Scully, Revox,
etc. professional machines. This unit, the F4460 although an Ampex was
built for the consumer market. and although the electronics was superb,
just about up to par with the professional machines, the transport
however left a lot to be desired.

To keep the costs down, (under a grand at the time, I think) they had to
chinch on something, and it was the deck. The studio machines employed
three motors. There was a main, and also a take up, and a hold back
motor. These two torque motors would not spin during normal operation but
were used to maintain proper tape tension on the heads.

Ampex had a few of these consumer type machines on the market at the time
that used similar other cheaper techniques to try to accomplish the same
thing as the pro machines. For instance Instead of a take up torque motor
there was a slipping clutch on the take up pulley. And for hold back
tension, instead of a motor tensioning the tape across the heads a felt
washer jammed the tape against a guide on the left side of the machine.
This washer would eventually load up with tape material, the transport
would start wowing and the washer would have to be removed, cleaned with
alcohol and reinstalled. A pain in the ass but worth it to have an Ampex.

I didn't ever really recall ever having a speed problem like I'm having
with mine with one of these consumer type machines, or even ever having
to check speed as referenced from an alignment tape as I did here with
the scope. They just always seemed to be on speed.

So Jurb to answer some of your questions, or suggestions, yes I am in the
US, New Hampshire to be exact. We haven't seceded from the Union yet,
although sometimes I wish we would. I tried checking RPM both ways;
unloaded and then loaded with belts capstan engaged, and then
"overloaded" (the finger on the pulley test). And through it all the
motor maintained constant torque and speed. Both the motor and flywheel
turn freely. The motor actually has two fill holes for each bushing. I
was able to stick a hypo filled with 10W into each hole and hit what
seemed like a felt sponge around an oilite bearing. Besides if either one
of these items was stiff I would expect to see a speed fluctuation
problem, which I don't. The capstan bushing is also tight. Other than
that I can add that this machine had a very easy life before I acquired
it. It was hardly used at all. Tomorrow I'll play with the cap value and
see what happens.

Really thought this thing would be off my bench by now, and back in the
entertainment center and I'd be listening to my Grateful Dead tapes.
****en bummer. Lenny

Maybe a silly suggestion, but check your scope 1khz signal.
Because those are not very reliable signal sources, specially
in old scopes. The square wave is usually oke, but the frequency
might be off. Maybe your voltmeter has a frequency measurement range.


I have seen older machines run slow because the idler wheel has dried out so
much that it's circumference has actually contracted noticeably.

Also, do not rule out an issue with the motor pully - the idler could be
running at a slightly lower height, if the pulley has a curved face. The
motor mounting bushings could be deteriorated, causing a height issue.

In my experience - if it were the motor cap, it would slow down and stop.
Also, the cap would probably be leaking noticeably, possibly also getting
hot.


Mark Z.

Mark Zacharias wrote:

I have seen older machines run slow because the idler wheel has dried out so
much that it's circumference has actually contracted noticeably.


** Got some news for you - pal.

The exact diameter of an idler wheel is irrelevant.

Cos all any idler does to transfer the surface speed of one rotating object to another.


..... Phil

On 12/17/2014 12:53 AM, wrote:
I'm working on my old Ampex 4460 reel to reel machine. (work is slow), and I'd like to listen to some of my old tapes. I cleaned and lubricated it, demagnetized the heads and put a tape of some familiar music on, and I thought it seemed a bit slow. So I repeated it with other tapes and then followed with an Ampex frequency response alignment tape. The scope was calibrated to 1.0ms off the 1KHZ square wave output and then I looked at the the 1KHZ sine wave off the tape. The period was approximately 1.40ms which appears to translate to 714HZ. Truly hard to believe that it's running that slow, but I don't think that the equipment is lying.

So I next got out the Strobeotac and put it on the motor capstan. The motor is rated for 1850 RPM at 115V, and it's running rock solid at 1795. I tried loading it while watching the speed and it remains steady, so it doesn't appear to be a load problem. Could such a slight motor speed reduction cause a 25 percent reduction in the frequency of my 1KHZ test tone off the tape? It doesn't seem possible, but I don't know.

The motor has a label that reads that it uses a 3.0UF 330V capacitor. I haven't investigated this yet, but with four wires going into it I figure that the cap must be on the chassis somewhere. I wouldn't think that a cap problem though would cause my RPM's to drop 55RPM would it? Oh and I have no service manual, however I don't think that service manual would do me much good with this problem anyway.


If anyone has any thoughts on this I'd sure appreciate hearing them. Thanks, Lenny

Good morning,

While I realized that the model is a F4460, is the machine what they
also call an F-44? The last 2 digits might just tell you what speeds or
cabinet the machine came in, or if it was 1/4 or 1/2 track.

Anyway, if it is an F44 (Fineline 44?) I have a recollection of what
Ampex techs call a "Dropped capstan flywheel" This is where the large
cast flywheel dropped down on the capstan shaft be cause the press fit
wasn't tight enough. I think you can check this by taking the top panel
off the unit so you can really see the flywheel, and just try pulling up
on it. If that's the case then you can take the whole thing out of the
machine, clean the capstan shaft and flywheel from grease, and refit the
flywheel with some epoxy so it stays where it it supposed to.

If this is an F44, contact me off-group. I might have a manual for the
thing somewhere in the archives.

Regards,
Tim Schwartz
Bristol Electronics

"Phil Allison" wrote in message
...
Sjouke Burry wrote:



Maybe a silly suggestion, but check your scope 1khz signal.
Because those are not very reliable signal sources, specially
in old scopes. The square wave is usually oke, but the frequency
might be off. Maybe your voltmeter has a frequency measurement range.


** That might be the case OR the capstan roller has gone smooth and hard
with age and is failing to control the speed of the tape through the capstan
gate.

With this sort of defect, tape speed can increase or decrease, depending
whether the take up reel or supply reel has more torque. A simple test is to
see if it is easy to pull tape through the capstan gate with the machine
turned off - if it is, you have a problem.

Having serviced many Roland tape echo machines made back in the 1980s (the
famous Space Echo and Chorus Echo models ) I can say the one fault common to
practically ALL examples seen is a shiny, smooth pinch roller.

Since no new supply of suitable rollers exists, I fit the old one with a
suitable shaft and lock it into the chuck of a bench drill spinning at
600rpm - then, using finger pressure on a piece of fine sand paper wrapped
around strip of wood, gently remove the shiny surface & restore the needed
matt one.


.... Phil



This stuff is really good on pinch rollers.
http://www.amazon.co.uk/AF-Internati...ds=platenclene


I once bought a bottle of Teac pinch roller cleaner, and it was totally
useless.



Gareth.

On Fri, 19 Dec 2014 14:56:02 +0000, Gareth Magennis wrote:

Since no new supply of suitable rollers exists, I fit the old one with a
suitable shaft and lock it into the chuck of a bench drill spinning at
600rpm - then, using finger pressure on a piece of fine sand paper
wrapped around strip of wood, gently remove the shiny surface & restore
the needed matt one.

But why does it matter? The pinch roller does not need friction to the
tape. It is the capstan that needs that. I can see you might need some
resilience so that the tape is not nipped too tightly and thus reduce the
contact pressure, but that's not really a surface attribute.

Mike.

"Mike" wrote in message
o.uk...
On Fri, 19 Dec 2014 14:56:02 +0000, Gareth Magennis wrote:

Since no new supply of suitable rollers exists, I fit the old one with a
suitable shaft and lock it into the chuck of a bench drill spinning at
600rpm - then, using finger pressure on a piece of fine sand paper
wrapped around strip of wood, gently remove the shiny surface & restore
the needed matt one.

But why does it matter? The pinch roller does not need friction to the
tape. It is the capstan that needs that. I can see you might need some
resilience so that the tape is not nipped too tightly and thus reduce the
contact pressure, but that's not really a surface attribute.

Mike.



I didn't write that, Phil Allison did.



Gareth.

wrote:



So I next got out the Strobeotac and put it on the motor capstan. The
motor is rated for 1850 RPM at 115V, and it's running rock solid at 1795.
1850?? How can the motor do 1850 on 60 Hz power? Many tape decks used
hysteresis-synchronous motors, so they were designed to spin up as
induction motors and then lock to the mains as synchronous.
A 4-pole motor would run at exactly 1800.0 RPM.

1795 with a strobotac is probably 1800, and your strobotac is
just a hair off calibration. You might just use a nean lamp
in series with a resistor and diode to make an exact 60 Hz
strobe, and see if a mark on the motor shaft stands still.


Jon

Mike wrote:

Phil Allison wrote:

Since no new supply of suitable rollers exists, I fit the old one with a
suitable shaft and lock it into the chuck of a bench drill spinning at
600rpm - then, using finger pressure on a piece of fine sand paper
wrapped around strip of wood, gently remove the shiny surface & restore
the needed matt one.

But why does it matter? The pinch roller does not need friction to the
tape.

** It absolutely does.

The simple explanation is in the words you snipped.


It is the capstan that needs that.

** The capstan has no grip to the tape - since polished steel and smooth tape have no mutual friction.

I can see you might need some
resilience so that the tape is not nipped too tightly and thus reduce the
contact pressure, but that's not really a surface attribute.

** A shiny surfaced roller has no grip to the capstan.

Why the heck do you think pinch rollers ( along with idler tyres and drive belts) are made from soft rubber in the first place ?

You ever serviced a tape recorder in your life ?


..... Phil

On Fri, 19 Dec 2014 13:58:10 -0800, Phil Allison wrote:

Mike wrote:

Phil Allison wrote:

Since no new supply of suitable rollers exists, I fit the old one
with a suitable shaft and lock it into the chuck of a bench drill
spinning at 600rpm - then, using finger pressure on a piece of fine
sand paper wrapped around strip of wood, gently remove the shiny
surface & restore the needed matt one.

But why does it matter? The pinch roller does not need friction to the
tape.

** It absolutely does.

The simple explanation is in the words you snipped.


It is the capstan that needs that.

** The capstan has no grip to the tape - since polished steel and
smooth tape have no mutual friction.

I can see you might need some resilience so that the tape is not nipped
too tightly and thus reduce the contact pressure, but that's not really
a surface attribute.

** A shiny surfaced roller has no grip to the capstan.

Why the heck do you think pinch rollers ( along with idler tyres and
drive belts) are made from soft rubber in the first place ?

You ever serviced a tape recorder in your life ?

No need to be rude! Actually I have only serviced special purpose players,
for a decade or three until they were discarded in favour of CD drives.
The media are all pre-recorded.

I said why I thought the pinch roller needed to be resilient; just a
matter of physics and pinch pressure. But now I see that you are relying
on an unstated but reasonable assumption: that the pinch roller is wider
than the tape so gets driven by the capstan on its margins and drives the
tape between those margins. You could, of course, have explained that
instead of ranting...

Mike.

Mike wrote:
Phil Allison wrote:
:

Phil Allison wrote:

Since no new supply of suitable rollers exists, I fit the old one
with a suitable shaft and lock it into the chuck of a bench drill
spinning at 600rpm - then, using finger pressure on a piece of fine
sand paper wrapped around strip of wood, gently remove the shiny
surface & restore the needed matt one.

But why does it matter? The pinch roller does not need friction to the
tape.

** It absolutely does.

The simple explanation is in the words you snipped.


It is the capstan that needs that.

** The capstan has no grip to the tape - since polished steel and
smooth tape have no mutual friction.

I can see you might need some resilience so that the tape is not nipped
too tightly and thus reduce the contact pressure, but that's not really
a surface attribute.

** A shiny surfaced roller has no grip to the capstan.

Why the heck do you think pinch rollers ( along with idler tyres and
drive belts) are made from soft rubber in the first place ?

You ever serviced a tape recorder in your life ?

No need to be rude!


** Nothing rude about what I posted.

You clearly have no idea how a capstan tape drive works.


I said why I thought the pinch roller needed to be resilient; just a
matter of physics and pinch pressure.

** Makes no sense.

But now I see that you are relying
on an unstated but reasonable assumption: that the pinch roller is wider
than the tape so gets driven by the capstan on its margins and drives the
tape between those margins.


** Whaaaaattt - so you have never seen a capstan drive tape machine ?

Yet you still decided to argue with me about my clearly written, totally correct post, by snipping and ignoring the bits you completely misunderstood.


You could, of course, have explained that instead of ranting...


** The one rating is YOU - pal.

FFS - YOU could have admitted that YOU had no idea how a capstan tape dive worked instead of making guesses and bull****ting.

FYI:

The pinch roller is CRUCIAL to the operation - it traps the tape against the capstan shaft and resists tensions coming from the supply and take up reels. The roller's height is about twice the width of the tape so it contacts the capstan directly and is driven around by it.

The pinch roller is generally mounted on a spring loaded arm, which is held back opening a small gap unless the machine is in play or record mode. When in play or record mode, the spring loaded arm is released and holds the pinch roller firmly against the capstan trapping the tape in between.

The roller must have a flat surface, with a good amount of grip to the capstan shaft when engaged. It must also grip the tape and the shaft it turns on must be exactly parallel with the capstan itself.

A worn or old pinch roller typically has a "glazed" surface that has almost no grip to the capstan or tape - or else it may become barrel shaped. A barrel shaped roller skews the tape up or down the capstan, causing the tape to spill or wind around the roller.

With a cassette deck or VCR, the capstan drive mechanism is hidden from the operator - but with a reel to reel recorder or tape echo it is highly visible cos the tape must be manually threaded through the capstan gate.

As Pete Townshend famously said " .. the simple thing you see are all complicated ... "

Capice ?


.... Phil

Phil Allison wrote:
Mark Zacharias wrote:

I have seen older machines run slow because the idler wheel has dried out so
much that it's circumference has actually contracted noticeably.


** Got some news for you - pal.

The exact diameter of an idler wheel is irrelevant.

Cos all any idler does to transfer the surface speed of one rotating object to another.

I have to admit that your explanations for pinch rollers is dead on. A worn or dry roller would cause slippage though, so rough it up and try again.

As for the OP, Not sure how much I'd trust a 400 year old tach. It may be time for a cardboard disc and a neon light to check for speed problems with the motor.
You don't need as many lines as on a turntable either.

On 12/17/2014 12:53 AM, wrote:
I'm working on my old Ampex 4460 reel to reel machine. (work is slow), and I'd like to listen to some of my old tapes. I cleaned and lubricated it, demagnetized the heads and put a tape of some familiar music on, and I thought it seemed a bit slow. So I repeated it with other tapes and then followed with an Ampex frequency response alignment tape. The scope was calibrated to 1.0ms off the 1KHZ square wave output and then I looked at the the 1KHZ sine wave off the tape. The period was approximately 1.40ms which appears to translate to 714HZ. Truly hard to believe that it's running that slow, but I don't think that the equipment is lying.

So I next got out the Strobeotac and put it on the motor capstan. The motor is rated for 1850 RPM at 115V, and it's running rock solid at 1795. I tried loading it while watching the speed and it remains steady, so it doesn't appear to be a load problem. Could such a slight motor speed reduction cause a 25 percent reduction in the frequency of my 1KHZ test tone off the tape? It doesn't seem possible, but I don't know.

The motor has a label that reads that it uses a 3.0UF 330V capacitor. I haven't investigated this yet, but with four wires going into it I figure that the cap must be on the chassis somewhere. I wouldn't think that a cap problem though would cause my RPM's to drop 55RPM would it? Oh and I have no service manual, however I don't think that service manual would do me much good with this problem anyway.


If anyone has any thoughts on this I'd sure appreciate hearing them. Thanks, Lenny

Hello everybody,

I doubt that his issue is a pinch roller no matter how badly glazed it
is as his machine is running SLOW, and it the tape is being pulled ahead
by the take-up torque overpowering the capstan/pinch roller, it would be
running fast.

Regards,
Tim Schwartz
Bristol Electronics

Tim Schwartz wrote:


doubt that his issue is a pinch roller no matter how badly glazed it
is as his machine is running SLOW, and it the tape is being pulled ahead
by the take-up torque overpowering the capstan/pinch roller, it would be
running fast.


** But a capstan spinning against a glazed roller will slip and hence not drive it round at full speed.

Most of my recent experience is with Roland tape echoes which use a 5 metre long loop squirming around in a box. Back tension come from pairs of felt pads the tape passes between as it leaves and enters the box.

When the roller is glazed, tape speed is slow and unsteady.

Also, tape becomes slightly sticky with age and grips to the heads as it passes over them - so much so that in some cases the loop will stop moving completely until you lift the tape off the heads and start again. This is the case even when the pinch roller in perfect condition.

The fix here is to clean all the heads and guides and replace the loop.

..... Phil

On 21/12/2014 13:11, Phil Allison wrote:
Mike wrote:
Phil Allison wrote:
:

Phil Allison wrote:

Since no new supply of suitable rollers exists, I fit the old one
with a suitable shaft and lock it into the chuck of a bench drill
spinning at 600rpm - then, using finger pressure on a piece of fine
sand paper wrapped around strip of wood, gently remove the shiny
surface & restore the needed matt one.

But why does it matter? The pinch roller does not need friction to the
tape.

** It absolutely does.

The simple explanation is in the words you snipped.


It is the capstan that needs that.

** The capstan has no grip to the tape - since polished steel and
smooth tape have no mutual friction.

I can see you might need some resilience so that the tape is not nipped
too tightly and thus reduce the contact pressure, but that's not really
a surface attribute.

** A shiny surfaced roller has no grip to the capstan.

Why the heck do you think pinch rollers ( along with idler tyres and
drive belts) are made from soft rubber in the first place ?

You ever serviced a tape recorder in your life ?

No need to be rude!


** Nothing rude about what I posted.

You clearly have no idea how a capstan tape drive works.


I said why I thought the pinch roller needed to be resilient; just a
matter of physics and pinch pressure.

** Makes no sense.

But now I see that you are relying
on an unstated but reasonable assumption: that the pinch roller is wider
than the tape so gets driven by the capstan on its margins and drives the
tape between those margins.


** Whaaaaattt - so you have never seen a capstan drive tape machine ?

Yet you still decided to argue with me about my clearly written, totally correct post, by snipping and ignoring the bits you completely misunderstood.


You could, of course, have explained that instead of ranting...


** The one rating is YOU - pal.

FFS - YOU could have admitted that YOU had no idea how a capstan tape dive worked instead of making guesses and bull****ting.

FYI:

The pinch roller is CRUCIAL to the operation - it traps the tape against the capstan shaft and resists tensions coming from the supply and take up reels. The roller's height is about twice the width of the tape so it contacts the capstan directly and is driven around by it.

The pinch roller is generally mounted on a spring loaded arm, which is held back opening a small gap unless the machine is in play or record mode. When in play or record mode, the spring loaded arm is released and holds the pinch roller firmly against the capstan trapping the tape in between.

The roller must have a flat surface, with a good amount of grip to the capstan shaft when engaged. It must also grip the tape and the shaft it turns on must be exactly parallel with the capstan itself.

A worn or old pinch roller typically has a "glazed" surface that has almost no grip to the capstan or tape - or else it may become barrel shaped. A barrel shaped roller skews the tape up or down the capstan, causing the tape to spill or wind around the roller.

With a cassette deck or VCR, the capstan drive mechanism is hidden from the operator - but with a reel to reel recorder or tape echo it is highly visible cos the tape must be manually threaded through the capstan gate.

As Pete Townshend famously said " .. the simple thing you see are all complicated ... "

Capice ?


.... Phil


Excellent description Phil.

Thank you

Col

---
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"Gareth Magennis" wrote in message
...

"Phil Allison" wrote in message
...
Sjouke Burry wrote:



Maybe a silly suggestion, but check your scope 1khz signal.
Because those are not very reliable signal sources, specially
in old scopes. The square wave is usually oke, but the frequency
might be off. Maybe your voltmeter has a frequency measurement range.


** That might be the case OR the capstan roller has gone smooth and hard
with age and is failing to control the speed of the tape through the
capstan gate.

With this sort of defect, tape speed can increase or decrease, depending
whether the take up reel or supply reel has more torque. A simple test is
to see if it is easy to pull tape through the capstan gate with the
machine turned off - if it is, you have a problem.

Having serviced many Roland tape echo machines made back in the 1980s (the
famous Space Echo and Chorus Echo models ) I can say the one fault common
to practically ALL examples seen is a shiny, smooth pinch roller.

Since no new supply of suitable rollers exists, I fit the old one with a
suitable shaft and lock it into the chuck of a bench drill spinning at
600rpm - then, using finger pressure on a piece of fine sand paper wrapped
around strip of wood, gently remove the shiny surface & restore the needed
matt one.


... Phil



This stuff is really good on pinch rollers.
http://www.amazon.co.uk/AF-Internati...ds=platenclene

Oh you little darlin' Gareth ! This was one of my favourite workshop
chemicals. I had one and it lasted years and years. When it ran out, I
really mourned as I was unable to find it still for sale anywhere. As soon
as Crimbo is out of the way, I will be ordering a can ! :-)

Arfa



Gareth.

"Sofa Slug" wrote in message
...
On 12/17/2014 10:18 AM, wrote:

The OEM flat belt though was very tired and had "assumed the
position"
of an oval from sitting in one position unused for so long. I
couldn't find anything around here having that circumference that was
2.0 mm thick so as a temporary measure I substituted a much thinner
belt. There is a very slight amount of wow which can be seen when
looking at the capstan flywheel with the strobe using this substitute
belt, and I'm guessing that it could be stretching back and forth
ever so slightly as it spins, but you really don't notice it on music
and it's only temporary until I can find something a little more
appropriate. I wouldn't think that a thinner belt would contribute to
a speed error, or am I wrong in making that assumption? Lenny

I would put the correct belt on there before getting into other minutia,
otherwise you may just end up chasing your tail.


Seconded. I have had many Aiwas that use a single motor dual cassette deck
come through my workshop over the years, that have had the main drive belts
replaced with two of dissimilar thicknesses. One might be a 1 mm square
section and the other 1.2 mm. When this is the case, it is impossible to get
both decks running at the same speed, even though it is a single motor
driving both. When two belts of the same thickness are fitted speed on both
decks is identical.

Arfa

Arfa Daily wrote:

"Gareth Magennis" wrote:

This stuff is really good on pinch rollers.
http://www.amazon.co.uk/AF-Internati...ds=platenclene

Oh you little darlin' Gareth ! This was one of my favourite workshop
chemicals. I had one and it lasted years and years. When it ran out, I
really mourned as I was unable to find it still for sale anywhere. As soon
as Crimbo is out of the way, I will be ordering a can ! :-)


I took a quart glass bottle to a local print shop and they filled it
with platen cleaner for $10. They buy it in 55 gallon drums. Smaller
shops buy it in five gallon cans.
--
Anyone wanting to run for any political office in the US should have to
have a DD214, and a honorable discharge.

Tim Schwartz wrote:

Good morning,

While I realized that the model is a F4460, is the machine what they
also call an F-44? The last 2 digits might just tell you what speeds or
cabinet the machine came in, or if it was 1/4 or 1/2 track.

Anyway, if it is an F44 (Fineline 44?) I have a recollection of what
Ampex techs call a "Dropped capstan flywheel" This is where the large
cast flywheel dropped down on the capstan shaft be cause the press fit
wasn't tight enough. I think you can check this by taking the top panel
off the unit so you can really see the flywheel, and just try pulling up
on it. If that's the case then you can take the whole thing out of the
machine, clean the capstan shaft and flywheel from grease, and refit the
flywheel with some epoxy so it stays where it it supposed to.

If this is an F44, contact me off-group. I might have a manual for the
thing somewhere in the archives.


I saw a lot of loose flywheels on cheap 8-track tape decks around
1970. We would pull the capstan and flywheel, then use a small center
punch and hammer to put four equally spaced dents near the capstan, on
the bottom side of the flywheel.


--
Anyone wanting to run for any political office in the US should have to
have a DD214, and a honorable discharge.

On 12/19/2014 01:58 PM, Phil Allison wrote:
Mike wrote:

Phil Allison wrote:

Since no new supply of suitable rollers exists, I fit the old one with a
suitable shaft and lock it into the chuck of a bench drill spinning at
600rpm - then, using finger pressure on a piece of fine sand paper
wrapped around strip of wood, gently remove the shiny surface & restore
the needed matt one.

But why does it matter? The pinch roller does not need friction to the
tape.

** It absolutely does.

The simple explanation is in the words you snipped.


It is the capstan that needs that.

** The capstan has no grip to the tape - since polished steel and smooth tape have no mutual friction.

I can see you might need some
resilience so that the tape is not nipped too tightly and thus reduce the
contact pressure, but that's not really a surface attribute.

** A shiny surfaced roller has no grip to the capstan.

Why the heck do you think pinch rollers ( along with idler tyres and drive belts) are made from soft rubber in the first place ?

You ever serviced a tape recorder in your life ?


.... Phil


It's the lack of pliabililty. They call it a pinch roller because it
pinches the tape. A hard rubber puck is useless. The exact dimension
isn't critical as long as the bearings fit and the plunger goes far enough.

dave wrote:

Phil Allison wrote:

Since no new supply of suitable rollers exists, I fit the old one with a
suitable shaft and lock it into the chuck of a bench drill spinning at
600rpm - then, using finger pressure on a piece of fine sand paper
wrapped around strip of wood, gently remove the shiny surface & restore
the needed matt one.


It's the lack of pliabililty. They call it a pinch roller because it
pinches the tape. A hard rubber puck is useless. The exact dimension
isn't critical as long as the bearings fit and the plunger goes far enough.


** You must be thinking of pinch rollers used in VCRs which often have an internal ball race.

The vast majority RR and echo machine rollers simply have a plain bearing running on a shaft of about 4 or 5mm dia.

All the Roland 1/4 inch tape echos have a roller that is 12mm x 28mm running on a 6mm shaft.


..... Phil

On 01/03/2015 04:10 PM, Phil Allison wrote:
dave wrote:

Phil Allison wrote:

Since no new supply of suitable rollers exists, I fit the old one with a
suitable shaft and lock it into the chuck of a bench drill spinning at
600rpm - then, using finger pressure on a piece of fine sand paper
wrapped around strip of wood, gently remove the shiny surface & restore
the needed matt one.


It's the lack of pliabililty. They call it a pinch roller because it
pinches the tape. A hard rubber puck is useless. The exact dimension
isn't critical as long as the bearings fit and the plunger goes far enough.


** You must be thinking of pinch rollers used in VCRs which often have an internal ball race.

The vast majority RR and echo machine rollers simply have a plain bearing running on a shaft of about 4 or 5mm dia.

All the Roland 1/4 inch tape echos have a roller that is 12mm x 28mm running on a 6mm shaft.

The rotating capstan controls the speed, the roller makes sure the tape
doesn't slip. There used to be a couple high end machines without pinch
rollers from Japan.

I spent many years fixing Ampex 600, 300, 351, 440, PR10; Otari MX5050;
ATC, Spartamatic, ITC cart machines. If the reel tension is right the
roller barely does anything.

I love when you turn the Space Echoes up too high and they make their
own music.