8:29 PMMichael Terrell wrote:
"- show quoted text -
I've woken up to -40F, during survival training.

I've installed more fiberglass batts than I care to think about,
starting in the early '60s. "

Then you must almost never turn your heat on.

'Murricans, thinking they all tough by never
using heat in the winter...

On Tue, 15 Dec 2015 17:21:14 -0800 (PST),
wrote:

If I got out of bed and it was 45 F, I would be looking into the heating
system first. I don't function when it is that cold.

http://802.11junk.com/jeffl/pics/home/slides/wood-burner.html
http://802.11junk.com/jeffl/pics/home/slides/firewood-2015.html

Below about 45F, I have problems working, especially when I'm walking
around the house in pajamas and no shoes. I do it often and it
doesn't bother me much. However, that requires that I keep moving,
which is often difficult in front to the computah. So, I fire up the
wood burner and run the temperature up to 60 to 70F.

Sounds like you may want to look into a solid state drive for the computer
so it will start up cold. "

An SSD is in the works. The problem is that every time I buy one for
myself, some customer arrives and needs it more. Since prices are
dropping, I don't mind delaying my SSD upgrade. However, for the
present situation, I'm looking into an adjustable cat or dog warming
electric blanket. I had a mysterious data corruption problem about a
month ago, when it began to become cold, that was probably due to the
startup problem. I recovered fairly easily, but it burned too much
time.

If I got out of bed and it was that cold, I would be looking
into some INSULATION first! Something 'Murricans seem
to be averse to, even after decades of evidence in favor
of it.

This is not a conventional house:
http://802.11junk.com/jeffl/pics/home/slides/BL-house3.html
Insulation is possible, but there are other priorities that come
first. Eventually, I'll need to build up the roof, which is where
insulation will do the most good. One of my neighbors did that to
their house that was similarly built, and it worked very well.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

wrote:

8:29 PMMichael Terrell wrote:
"- show quoted text -
I've woken up to -40F, during survival training.

I've installed more fiberglass batts than I care to think about,
starting in the early '60s. "

Then you must almost never turn your heat on.

'Murricans, thinking they all tough by never
using heat in the winter...


No, but then I live in Florida.

I have a 1000W electric heater, for the rare times that it is in the
30s for several days in a row.

On Tue, 15 Dec 2015 18:05:36 -0800, Jeff Liebermann
wrote:

On Tue, 15 Dec 2015 17:21:14 -0800 (PST),
wrote:

If I got out of bed and it was 45 F, I would be looking into the heating
system first. I don't function when it is that cold.

http://802.11junk.com/jeffl/pics/home/slides/wood-burner.html
http://802.11junk.com/jeffl/pics/home/slides/firewood-2015.html

Below about 45F, I have problems working, especially when I'm walking
around the house in pajamas and no shoes. I do it often and it
doesn't bother me much. However, that requires that I keep moving,
which is often difficult in front to the computah. So, I fire up the
wood burner and run the temperature up to 60 to 70F.

Sounds like you may want to look into a solid state drive for the computer
so it will start up cold. "

An SSD is in the works. The problem is that every time I buy one for
myself, some customer arrives and needs it more. Since prices are
dropping, I don't mind delaying my SSD upgrade. However, for the
present situation, I'm looking into an adjustable cat or dog warming
electric blanket. I had a mysterious data corruption problem about a
month ago, when it began to become cold, that was probably due to the
startup problem. I recovered fairly easily, but it burned too much
time.

If I got out of bed and it was that cold, I would be looking
into some INSULATION first! Something 'Murricans seem
to be averse to, even after decades of evidence in favor
of it.

This is not a conventional house:
http://802.11junk.com/jeffl/pics/home/slides/BL-house3.html
Insulation is possible, but there are other priorities that come
first. Eventually, I'll need to build up the roof, which is where
insulation will do the most good. One of my neighbors did that to
their house that was similarly built, and it worked very well.
Greetings Jeff,
Your house makes me nostalgic. I grew up on the other side and at the
base of the Santa Cruz Mountains in Saratoga. Hitchhiked over to
Santa Cruz and then either north or south, depending on my mood. North
for the beaches, south for Capitola. Or right into Santa Cruz for the
Boardwalk. I hiked all over the Santa Cruz Mountains, in the summer I
hiked and camped as much as possible. Dug for sharks teeth in Scott's
Valley. The longest one I found was over three inches long but was
broken into two parts. It was in a dry rivulet in the sand parking lot
where we, and everybody else, dug for sharks teeth. I pretty much
stopped hitchhiking when it became nearly impossible to get a ride
because of that crazy guy who was killing hitchhiking girls. His mom
and her friend too. Buried their heads under stepping stones in the
yard. I think he was named Edmund Kemper. I remember buying chilled
dungeness crab, butter, sourdough bread, and beer and sitting with
friends on a dock eating it.
Cheers,
Eric

In article ,
Jeff Liebermann wrote:

However, for the
present situation, I'm looking into an adjustable cat or dog warming
electric blanket.

Cat's aren't particularly adjustable, warmed or otherwise. They're
notoriously stubborn.

On Wed, 16 Dec 2015 11:30:44 -0800, (Dave
Platt) wrote:

In article ,
Jeff Liebermann wrote:

However, for the
present situation, I'm looking into an adjustable cat or dog warming
electric blanket.

Cat's aren't particularly adjustable, warmed or otherwise. They're
notoriously stubborn.

Cat warmer:
http://802.11junk.com/jeffl/pics/drivel/slides/Cat-warmer.html
Actually, that's the neighbors cat. She typed "don't you dare try to
move me" on the keyboard as a warning. I found a different computer
to work on.

Incidentally, the noisy fan on cold start turned out to the small fan
on the video card. Cleaning and switching to a multi-viscosity oil
change seems to have solved the problem.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

Once upon a time, I was temporarily put in charge of marine radio
manufactories production test department while they searched for
someone to replace my predicessor, who had apparently gone missing,
insane, or both.

Among the test techs was one who followed instructions dilligently,
but usually failed to understand what was expected. The techs were
told that in the transmitter RF chain, if they couldn't identify which
device lacked sufficient gain, they could just replace each device in
turn until the culprit was found. This was possible because there
were only 7 devices involved, and the most likely culprits were the
cheap TO-92 devices found at the oscillator end of the chain.
Unfortunately, that was not communicated to this individual, who
proceded to replace devices starting with the rather expensive 25 watt
VHF RF output transistor. Nobody said noticed until I went to the
parts room to replace a 25 watt device that I had blown up in
engineering, and was informed that production test had grabbed all the
available stock. I also noticed that someone had prefixed some of the
printed test procedures to include turning the power on to the test
equipment. I survived for about a month and was very happy when the
company finally hired someone to replace me.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

One of my customers in the computah repair business own a large house
that had been converted to college student housing. My guess is about
15 students crammed into every possible available space. I was hired
by the owner to maintain the Comcast internet, NAS server, printers,
phone system, wiring, and wi-fi, which are all part of the package.
The prime directive was to do everything necessary to prevent the
students from burning down the house, which I interpreted to mean not
let them make any changes or additions to the wiring or equipment.
That has worked fairly well by the honor system for about 8 years.

This morning, I get a phone call that the internet and some of the
phones are down. Upon interrogation, I determine that some of the
"makers[1]" in the house had "optimized" the performance of the
Comcast cable modem and VoIP systems yesterday. My initial guess was
that they had managed to scramble the ethernet cables on the 24 port
managed switch running several VLAN's. Unlike ordinary ethernet
switches, a managed switch with traffic logging, required that the
correct cable be connected to the correct port.

I had previously suggested that someone should take photographs of the
wiring for this exact purpose. Amazingly, the students found the
flash drive in the envolope that I had place in plain sight, and were
able to display how things were wired before the system was
"optimized". They were able to bring things back online in only a few
additional minutes (I could see the switch come up from home via SNMP)
and only waited a full hour before someone bothered to phone me that
it was fixed and I need not waste a service call to the house.

With such a wonderful example of initiative and organized
troubleshooting, I think there may be hope for our next generation of
our country's leaders.


[1] Make trouble, make a mess, make love, make things break, make a
quick exit, etc...
--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On Thu, 17 Dec 2015 13:30:22 -0500, "Ralph Mowery"
wrote:

Always start with the most expensive part. If it is not bad, it will be
when it is ripped out.

Never do anything that can't be undone.

I had a Toyota that started running vrey bad with about 130,000 miles on it.
I repalaced the simple things like the plugs, wires, coil and fuel filter.
Nothing helped. From there a Autozone trouble shooting chart indicated a
sensor that was about $ 500. I took it to the local Toyota dealer and let
them look at the problem as I did not want to spend $ 500 and not need that
part. They kept it about 3 weeks and changed a few other parts including
the spark plug wires as I did not use Toyota wire. Finally they changed
that $ 500 sensor and it ran like it should. I would have thought a dealer
could run some tests but seems like they were just parts changers. Really
ticked me off as they had put on about $ 150 worth of parts that were not
needed and still charged me for them not counting on the 3 weeks it took
them.

I had almost the same situation, except it was the rear oxygen sensor.
The dealer wanted to replace the very expensive catalytic converter.
The dealers computer diagnostics all pointed to the catalytic
converter. They even called the factory service support number, which
confirmed that the diagnostics conclusively pointed to the catalytic
converter. However, I was able to listen to this conversation and
detected considerable uncertainty and lack of competence on everyones
part. Something seemed wrong, so I decided to do some checking. The
internet was full of the usual mix of wisdom and useless garbage, but
I did manage to find an article suggesting that the rear oxygen sensor
tends to get contaminated by various exhaust products, and that since
it's two orders of magnitude cheaper than a catalytic converter, it
should be replaced first. I replaced it, and all as well.

I was curious as to what had just happened, so I went back to the
dealer, told them the story, and asked a few questions. Basically,
there is nobody in the system that knows how to troubleshoot a vehicle
without totally relying on the computerized hardware. The programming
is not intended to nail down the exact cause of a problem, only the
most probable causes, expecting the dealer to replace things in a
rational and logical order based on their experience. In other words,
the computer supplies a shopping list that usually includes a large
number of irrelevant replacement parts and procedures. When calling
factory service support, they don't have experienced techs on the
phones. They just read the computer screen. I was also told that it
was amazing that the diagnostics programs worked because the factory
was constantly making changes and improvements that affected
recommendations.

In my distant past, I had the displeasure of integrating BITE (built
in test equipment) in some radios. The test system caused more
failures than it detected. The diagnostics could be easily mislead,
producing insane results. Even worse, it could not diagnose itself.
All I can say is that such diagnostics are NOT easy to do, especially
with a moving target, such as an automobile.


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

"Jeff Liebermann" wrote in message
...
I was curious as to what had just happened, so I went back to the
dealer, told them the story, and asked a few questions. Basically,
there is nobody in the system that knows how to troubleshoot a vehicle
without totally relying on the computerized hardware. The programming
is not intended to nail down the exact cause of a problem, only the
most probable causes, expecting the dealer to replace things in a
rational and logical order based on their experience. In other words,
the computer supplies a shopping list that usually includes a large
number of irrelevant replacement parts and procedures. When calling
factory service support, they don't have experienced techs on the
phones. They just read the computer screen. I was also told that it
was amazing that the diagnostics programs worked because the factory
was constantly making changes and improvements that affected
recommendations.

At work there is a pipe that has about 150 psi of air on it and about 2
inches in diameter. This goes to a regulator that cuts it to about 75 psi
and then to a a control valve that is ran by a computer. This regular has a
habit of getting water in it and in the winter time turning to ice. I got a
call that the system was not working correctly so I cleared the ice from the
regulator. Then an engineer wanted me to rebuild or change out the control
valve because it was not working. I told her that I was not going to do it
unless there were more problems. She got very mad at me and told me that
her data from the computer said the control valve was not working. I told
her I did not care what her old data said, it was not the control valve.

The control valve can not control anyting if no air is getting to it for it
to control.

Had a lot more trouble out of some of the production engineers because of
the computer. The process probably monitored over 1000 points and stored
that data for a month. That data could be called up in a graphical form.
Only problem is some of the data points may be 1 to 5 moments apart.
Something could hapen and would not be caught during that time frame. Then
it would look like something other than the origional problem was the cause.

Computers are good,but you have to undestand what they are trying to tell
you and sometimes they are just wrong.

Um.... Um....

Have you checked the receptacle at home? And for proper polarity?

Some monitors will not function if not properly polarized. Just a thought.

Peter Wieck
Melrose Park, PA

" Basically,
there is nobody in the system that knows how to troubleshoot a vehicle
without totally relying on the computerized hardware. The programming
is not intended to nail down the exact cause of a problem, only the
most probable causes, expecting the dealer to replace things in a
rational and logical order based on their experience. "

Not even that. I think they may have been trying to rake you over the coals.. As far as I know, there is no code for "catalytic convertor". the second O2 sensor is supposed to detect slightly less oxygen than the first one. This assures the cat is installed and operating. the codes them selves read something like "O2 sensor #2 reading rich", or lean. Anyone with a brain should logically replace that first. Incidentally, for this system to work, it MUST waste some fuel by making it over rich. If the mixture is stoichometric, the catalytic has nothing to do. But that is a bit easier on the valves and a few other components.

Catalytics either get clogged or burnt out. Something has to happen, prolonged driving with a misfire for example. I don't know about you, but when I drive, I want the car to run right. If it has a miss I can't stand it. If anything I can't stand it. If it burns oil I junk it. (that's why I prefer GM, seems their engines and trannies last, problem is they fell out of the damn car back in the 1980s)

You know, if the auto service business was like the consumer electronics service business, they would have pretty much had to put that cat in for free, or lied to you and put the O2 sensor in for free. Guess which. And let's not even get started about doctors, them ****ers cut off the wrong leg and expect to get paid. And that is pretty bad, because if you have one leg there ARE solutions whereby you can walk. If you have no legs that is it. I hope the guy they did that to is the richest MF sitting in the world.

But anyway, for a time I was the go to guy on hard faults in cars. (I also learned that you can CLEAN an O2 sensor) Buddy brings me his Cutlass, one of the last years you could get the bulletproof 4-151 engine. Good reliable car. Runs like ****. It REALLY REALLY acts like low fuel pressure. (a later paragraph will discuss that) Alot of cars had low fuel pressure and would start and idle, and crawl but not run. Slow fuel delivery was a big thing for a while. But that has been checked. It has also been to Mr. Goodwrench for a fifty buck diagnosis and they said to replace the engine.

They didn't know who the **** they were talking to. They were trained to replace parts for fifty bucks an hour, we degreed cams, we had cranks machined down a thousandth or two and had them hard chromed back up to size. This is like having a forged crank, in fact better in some way. the olman had a 283 that did 9,400 RPM with a Racer Brown roller cam, ONE RPM higher it would wipe out bearing number one. They tried many things but at 9,400 RPM the laws of physics takes over and there was nothing you could do.

So anyway I drives the car up down the street, it cannot get out of its own way. Checking things out, I find the two possibilities are this crank sensor which is a bitch to change, or it jumped time. I took the air cleaner off and revved it up, and during part of the stroke it was spitting the injected gas out the top.

I said "Tear down for timing chain". (This guy was also a competent mechanic but this was a tough case) He said that they said this car does not have a timing chain, it has gears.

The next day he shows up and throws the tensioner on my kitchen table. Doesn't have a chain eh ? What kind of gears need that kind of tensioner ?

Another time my ex-lawyer had this pickup truck, I forget the make and model but it was a cheapie. It had linear torsion bar suspension, which means all the front end parameters are different. He had a tow hitch on a tow bar on the front so he could tow it with his camper. He said this is the only truck I could find that you could back up without the steering wheel whipping to a lock. It would track, and back up nicely so he wanted to keep it. Go camping and take your car with you kinda thing.

Maybe a year or so before he had the timing belt replaced. It would intermittently run like ****, not start, whatever. Nobody could figure it out.

Turns out the dodo who did the belt had lost the woodruff key and replaced it with an American version which was a bit too small. Over time it sheared, and the crank went where it wanted. Literally like 180 degrees off.

Now that is hard to detect. But we did detect it. We had to drive it too, apparently the inertia of revving and idling made it do it. Eventually we caught it, at one time the timing marks are right, and then they are wrong. W T F !

The wrong woodruff key had already mauled the crank so we brazed one in. You don't want to weld something like that in case it ever needs a front crank seal, but the brazing, and we thought about this, would stop the movement which was responsible for the failure because it just kept wearing away at it. Every compression and then power stroke moved it as this key was between the crank and the damper.

OK, that is not necessarily consumer electronics but others had looked at the thing coming up with all the wrong diagnoses. So it already had brand new plugs, module, sensors, wires, high performance lugnuts, the works.

How come some people are responsible if their diagnosis is incorrect and others are not ?

On Fri, 18 Dec 2015 07:49:23 -0800 (PST), "
wrote:

Um.... Um....

Who when where how why what?

Have you checked the receptacle at home? And for proper polarity?
Some monitors will not function if not properly polarized. Just a thought.

I don't think that's the problem of I would have been electrocuted
long ago. However, it was worth checking, especially since I did my
own wiring. So I dug out my tester:
https://en.wikipedia.org/wiki/Receptacle_tester
and walked it through the maze of power strips and extension cords.
Everything tests just fine.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

Any more recent successs stories to brag about?

C'mon, don't we all enjoy patting ourselves on the back, really?


Mark Z.

**I recall the first time (1980-ish) I discovered those fusible resistors
that go high after a few years. With no obvious signs of distress. Now I
just head straight for the buggers.

Then there's those low value (/=47 Ohms), 1/4W cracked carbon resistors
that go O/C when subjected to ca. 60+ Volts with no signs of burning
(Marantz 1200b, 240, 250M, 500 models). Over the years, I learned to
suspect any resistor over the value of 100k, if the circuit is displaying
some kind of mysterious fault that cannot be explained by a semiconductor
failure or cap leakage.

--
Trevor Wilson
www.rageaudio.com.au

---
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus



A brand new "war story".

As I am nearing the end of my career, I wonder if any one unit will be the
high water mark so far as feeling the satisfaction of fixing a really tough
one.

This may be it.

A Yamaha M-80 power amplifier. I've worked on a few in the past - difficult
but doable.

I've always thought that "M-80" was a humorously ironic model number for an
amplifier so flammable.

Initial inspection:

Burned resistors on both channels, a vented 1000uF 100v cap (one of a pair)
on the main board, lots of brown glue, some green corrosion visible on
component leads.

Strangely - only one output transistor was bad. I knew this was going to be
a tough one but I figured I could do it - just give the customer a pretty
high estimate.

Replaced those larger caps, lots of bad drivers, pre-drivers, signal
transistors, several burned and corroded resistors, one bias transistor.

Replaced the one bad output and it's mate. I figured the same current ripped
through both, so I wanted at least do that.

I knew the speaker relays would need service, so I took them out of order
and did that job.

Bringing up on a variac, the fires were out, bias adjusted OK, but no sound.
Another bad resistor.


Replaced this, but now there was a -86 volt(!) offset. Couple more bad
resistors.

Each time a component replaced it was necessary to monitor bias when
bringing it up.

Bring it up again, no offset but one channel oscillates. Fine. Trace down
and replace the bias transistor on that channel that was breaking down.
Replace it and: one channel low in gain, approximately 1/2 the other
channel.

Replace a bad 3.9K 1/2 watt resistor in the feedback loop. That was easy.
NOPE.

Now BOTH channels oscillate like crazy. Apparently a larger 3.9K 2W resistor
was corroded and got nudged while replacing the other. Replaced that. No
more oscillation. NOW:

Still no change on the gain problem.

Bad 430 ohm resistor hiding UNDER a power resistor, and not even visible
until the other was removed.

Unit now repaired and functioning properly.

This thing took approximately five whole days worth of bench time.

I'm going to spend a very generous amount of time patting myself on the back
for this one.


Mark Z.

On 3/02/2016 11:31 PM, Mark Zacharias wrote:
Any more recent successs stories to brag about?

C'mon, don't we all enjoy patting ourselves on the back, really?


Mark Z.

**I recall the first time (1980-ish) I discovered those fusible
resistors that go high after a few years. With no obvious signs of
distress. Now I just head straight for the buggers.

Then there's those low value (/=47 Ohms), 1/4W cracked carbon
resistors that go O/C when subjected to ca. 60+ Volts with no signs of
burning (Marantz 1200b, 240, 250M, 500 models). Over the years, I
learned to suspect any resistor over the value of 100k, if the circuit
is displaying some kind of mysterious fault that cannot be explained
by a semiconductor failure or cap leakage.

--
Trevor Wilson
www.rageaudio.com.au

---
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus



A brand new "war story".

As I am nearing the end of my career, I wonder if any one unit will be
the high water mark so far as feeling the satisfaction of fixing a
really tough one.

This may be it.

A Yamaha M-80 power amplifier. I've worked on a few in the past -
difficult but doable.

I've always thought that "M-80" was a humorously ironic model number for
an amplifier so flammable.

Initial inspection:

Burned resistors on both channels, a vented 1000uF 100v cap (one of a
pair) on the main board, lots of brown glue, some green corrosion
visible on component leads.

Strangely - only one output transistor was bad. I knew this was going to
be a tough one but I figured I could do it - just give the customer a
pretty high estimate.

Replaced those larger caps, lots of bad drivers, pre-drivers, signal
transistors, several burned and corroded resistors, one bias transistor.

Replaced the one bad output and it's mate. I figured the same current
ripped through both, so I wanted at least do that.

I knew the speaker relays would need service, so I took them out of
order and did that job.

Bringing up on a variac, the fires were out, bias adjusted OK, but no
sound.
Another bad resistor.


Replaced this, but now there was a -86 volt(!) offset. Couple more bad
resistors.

Each time a component replaced it was necessary to monitor bias when
bringing it up.

Bring it up again, no offset but one channel oscillates. Fine. Trace
down and replace the bias transistor on that channel that was breaking
down. Replace it and: one channel low in gain, approximately 1/2 the
other channel.

Replace a bad 3.9K 1/2 watt resistor in the feedback loop. That was
easy. NOPE.

Now BOTH channels oscillate like crazy. Apparently a larger 3.9K 2W
resistor was corroded and got nudged while replacing the other. Replaced
that. No more oscillation. NOW:

Still no change on the gain problem.

Bad 430 ohm resistor hiding UNDER a power resistor, and not even visible
until the other was removed.

Unit now repaired and functioning properly.

This thing took approximately five whole days worth of bench time.

I'm going to spend a very generous amount of time patting myself on the
back for this one.


**All for an amp worth, what(?), $300.00? It can be a bugger of a
business. How much can you charge your client? $200.00?

On the flip side, I did a couple of really ancient (ca. 1972) Accuphase
amps recently. The client was willing to spend around $700.00 on each.
He bought them for a song and they typically sell for a couple of Grand
on eBay.


--
Trevor Wilson
www.rageaudio.com.au

---
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus

Any more recent successs stories to brag about?

C'mon, don't we all enjoy patting ourselves on the back, really?


Mark Z.

Okay, one more. True story... This wasn't so much a difficult repair as it was the circumstance. 1980, hot summer day and my new girlfriend (who would be my wife) is having her HS graduation party when her parent's early 70s tube Magnavox console blacks out in a cloud of smoke leaving a clean horiz line. I was 21 at the time and looked younger, but of course being a TV tech I was asked to look at it. I pulled the chassis out and the area around the vert centering control was pitch black. That and the cigarette smoke and wood stove deposits made seeing what else was burned nearly impossible.

I borrowed the garden hose and a bottle of Fantastik (TM) and soaked the bottom of the chassis and rinsed so it sparkled, then left it out front in the hot sun. Later in the afternoon I put in two 10 ohm 5W resistors in place of the vert cent control and put it together, touched up the height and lin and it worked fine for a few more years.

When my father in law tells the story, he said that when he saw me hosing out the TV guts in the front yard he was thinking "oh sh$t I'm going to have to buy a new TV tomorrow".

"Trevor Wilson" wrote in message
...
On 3/02/2016 11:31 PM, Mark Zacharias wrote:
Any more recent successs stories to brag about?

C'mon, don't we all enjoy patting ourselves on the back, really?


Mark Z.

**I recall the first time (1980-ish) I discovered those fusible
resistors that go high after a few years. With no obvious signs of
distress. Now I just head straight for the buggers.

Then there's those low value (/=47 Ohms), 1/4W cracked carbon
resistors that go O/C when subjected to ca. 60+ Volts with no signs of
burning (Marantz 1200b, 240, 250M, 500 models). Over the years, I
learned to suspect any resistor over the value of 100k, if the circuit
is displaying some kind of mysterious fault that cannot be explained
by a semiconductor failure or cap leakage.

--
Trevor Wilson
www.rageaudio.com.au

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A brand new "war story".

As I am nearing the end of my career, I wonder if any one unit will be
the high water mark so far as feeling the satisfaction of fixing a
really tough one.

This may be it.

A Yamaha M-80 power amplifier. I've worked on a few in the past -
difficult but doable.

I've always thought that "M-80" was a humorously ironic model number for
an amplifier so flammable.

Initial inspection:

Burned resistors on both channels, a vented 1000uF 100v cap (one of a
pair) on the main board, lots of brown glue, some green corrosion
visible on component leads.

Strangely - only one output transistor was bad. I knew this was going to
be a tough one but I figured I could do it - just give the customer a
pretty high estimate.

Replaced those larger caps, lots of bad drivers, pre-drivers, signal
transistors, several burned and corroded resistors, one bias transistor.

Replaced the one bad output and it's mate. I figured the same current
ripped through both, so I wanted at least do that.

I knew the speaker relays would need service, so I took them out of
order and did that job.

Bringing up on a variac, the fires were out, bias adjusted OK, but no
sound.
Another bad resistor.


Replaced this, but now there was a -86 volt(!) offset. Couple more bad
resistors.

Each time a component replaced it was necessary to monitor bias when
bringing it up.

Bring it up again, no offset but one channel oscillates. Fine. Trace
down and replace the bias transistor on that channel that was breaking
down. Replace it and: one channel low in gain, approximately 1/2 the
other channel.

Replace a bad 3.9K 1/2 watt resistor in the feedback loop. That was
easy. NOPE.

Now BOTH channels oscillate like crazy. Apparently a larger 3.9K 2W
resistor was corroded and got nudged while replacing the other. Replaced
that. No more oscillation. NOW:

Still no change on the gain problem.

Bad 430 ohm resistor hiding UNDER a power resistor, and not even visible
until the other was removed.

Unit now repaired and functioning properly.

This thing took approximately five whole days worth of bench time.

I'm going to spend a very generous amount of time patting myself on the
back for this one.


**All for an amp worth, what(?), $300.00? It can be a bugger of a
business. How much can you charge your client? $200.00?

On the flip side, I did a couple of really ancient (ca. 1972) Accuphase
amps recently. The client was willing to spend around $700.00 on each. He
bought them for a song and they typically sell for a couple of Grand on
eBay.


--
Trevor Wilson
www.rageaudio.com.au

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After an initial assessment, I gave the customer an approximately 300.00
estimate.

Midway through the process I advised him it would be more.

Billed out at 400.00.

He hasn't picked it up yet, but it's part of a set with the preamp, tuner,
cd, and cassette so I'm not too worried.

Yeah - these days you take what you can get.

I was pretty confident I could fix it, but one problem kept hiding behind
the last one, and oscillation problems kinda turn my knees to jelly.


Mark Z.

"John-Del" wrote in message
...


Okay, one more. True story... This wasn't so much a difficult repair as it
was the circumstance. 1980, hot summer day and my new girlfriend (who
would be my wife) is having her HS graduation party when her parent's
early 70s tube Magnavox console blacks out in a cloud of smoke leaving a
clean horiz line. I was 21 at the time and looked younger, but of course
being a TV tech I was asked to look at it. I pulled the chassis out and
the area around the vert centering control was pitch black. That and the
cigarette smoke and wood stove deposits made seeing what else was burned
nearly impossible.

I borrowed the garden hose and a bottle of Fantastik (TM) and soaked the
bottom of the chassis and rinsed so it sparkled, then left it out front in
the hot sun. Later in the afternoon I put in two 10 ohm 5W resistors in
place of the vert cent control and put it together, touched up the height
and lin and it worked fine for a few more years.

When my father in law tells the story, he said that when he saw me hosing
out the TV guts in the front yard he was thinking "oh sh$t I'm going to
have to buy a new TV tomorrow".



Same thing happened to my younger brother when our family was visiting the
family of the older brother's wife.

Zenith TV died. My younger brother, who was either still in tech school or
early in his career, tore the set down to bits and pieces right there on the
living room floor, puzzled over it a bit, the light came on, ran down to the
Zenith distributor, picked up a part, got back over there and finished the
repair.

Two families (not to mention the two brothers) were sweating bullets on that
one.


Mark Z.

John-Del wrote: "When my father in law tells the story, he said that when he saw me hosing out the TV guts in the
front yard he was thinking "oh sh$t I'm going to have to buy a new TV tomorrow".


Good story with happy ending! Nowadays most folks
won't let me adjust their PICTURE menus for them,
let alone go component level. Sets are so reliable
today, with consistent image quality, yet people wonder
why they burn out after only 3-5 years.

Backlit TVs(LCD, LED) require a backlight to be seen,
and very often this setting, along with the others, are
left in factory/showroom mode, shortening the life of
the appliance. Getting set owners to understand this
basic fact, along with the benefits of correct setting of
the basic adjustments(brightness, contrast, color, etc),
is well-nigh impossible! A $300 full calibration is often
not necessary to achieve these goals.

On Thu, 4 Feb 2016 05:09:48 -0600, "Mark Zacharias"
wrote:

"Trevor Wilson" wrote in message
...
On 3/02/2016 11:31 PM, Mark Zacharias wrote:
Any more recent successs stories to brag about?

C'mon, don't we all enjoy patting ourselves on the back, really?


Mark Z.

**I recall the first time (1980-ish) I discovered those fusible
resistors that go high after a few years. With no obvious signs of
distress. Now I just head straight for the buggers.

Then there's those low value (/=47 Ohms), 1/4W cracked carbon
resistors that go O/C when subjected to ca. 60+ Volts with no signs of
burning (Marantz 1200b, 240, 250M, 500 models). Over the years, I
learned to suspect any resistor over the value of 100k, if the circuit
is displaying some kind of mysterious fault that cannot be explained
by a semiconductor failure or cap leakage.

--
Trevor Wilson
www.rageaudio.com.au

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A brand new "war story".

As I am nearing the end of my career, I wonder if any one unit will be
the high water mark so far as feeling the satisfaction of fixing a
really tough one.

This may be it.

A Yamaha M-80 power amplifier. I've worked on a few in the past -
difficult but doable.

I've always thought that "M-80" was a humorously ironic model number for
an amplifier so flammable.

Initial inspection:

Burned resistors on both channels, a vented 1000uF 100v cap (one of a
pair) on the main board, lots of brown glue, some green corrosion
visible on component leads.

Strangely - only one output transistor was bad. I knew this was going to
be a tough one but I figured I could do it - just give the customer a
pretty high estimate.

Replaced those larger caps, lots of bad drivers, pre-drivers, signal
transistors, several burned and corroded resistors, one bias transistor.

Replaced the one bad output and it's mate. I figured the same current
ripped through both, so I wanted at least do that.

I knew the speaker relays would need service, so I took them out of
order and did that job.

Bringing up on a variac, the fires were out, bias adjusted OK, but no
sound.
Another bad resistor.


Replaced this, but now there was a -86 volt(!) offset. Couple more bad
resistors.

Each time a component replaced it was necessary to monitor bias when
bringing it up.

Bring it up again, no offset but one channel oscillates. Fine. Trace
down and replace the bias transistor on that channel that was breaking
down. Replace it and: one channel low in gain, approximately 1/2 the
other channel.

Replace a bad 3.9K 1/2 watt resistor in the feedback loop. That was
easy. NOPE.

Now BOTH channels oscillate like crazy. Apparently a larger 3.9K 2W
resistor was corroded and got nudged while replacing the other. Replaced
that. No more oscillation. NOW:

Still no change on the gain problem.

Bad 430 ohm resistor hiding UNDER a power resistor, and not even visible
until the other was removed.

Unit now repaired and functioning properly.

This thing took approximately five whole days worth of bench time.

I'm going to spend a very generous amount of time patting myself on the
back for this one.


**All for an amp worth, what(?), $300.00? It can be a bugger of a
business. How much can you charge your client? $200.00?

On the flip side, I did a couple of really ancient (ca. 1972) Accuphase
amps recently. The client was willing to spend around $700.00 on each. He
bought them for a song and they typically sell for a couple of Grand on
eBay.


--
Trevor Wilson
www.rageaudio.com.au

---
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus


After an initial assessment, I gave the customer an approximately 300.00
estimate.

Midway through the process I advised him it would be more.

Billed out at 400.00.

He hasn't picked it up yet, but it's part of a set with the preamp, tuner,
cd, and cassette so I'm not too worried.

Yeah - these days you take what you can get.

I was pretty confident I could fix it, but one problem kept hiding behind
the last one, and oscillation problems kinda turn my knees to jelly.


Mark Z.

Mark,

These were the worst! I've seen 20 or more transistors blown on these
amps. I admire your tenacity. The Accuphases were so much easier to
repair.

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