Hi,
I'm a total beginner, but I have a pretty simple VCR issue that doesn't appear to be covered in Sam Goldwasser's VCR FAQ (http://www.repairfaq.org/sam/vcrfaq.htm) or David T. Ronan's Practical VCR Repair, based on the skimming I've done.

When I'm stopping or ejecting a tape, my back tension regulator takes too long to move out of the way, and the left shuttle assembly gets blocked on it - and pins it in place - on its way back to the front of the VCR. Basically, the two parts end up jamming each other, so neither can move, and it screws up the timing of the two shuttles as well as the gears underneath slip teeth.

What exactly is the mechanism that is supposed to make the back tension arm retract away from the full erase head and toward the tape door? Is it supposed to sit passively while the left shuttle assembly pushes it back toward the front, or is the VCR supposed to apply power to explicitly move it out of the way? If the VCR is meant to explicitly apply power, what controls the timing of this?

I half-expected this issue to be a common cause of jams and thoroughly covered by VCR repair resources, since the back tension arm literally crosses the path of the left shuttle assembly, but I haven't found anything about it yet. I can't imagine I'm the only person in the world who has ever had this happen to them.

My VCR has other issues that bring about this behavior initially, but this is the most pressing problem due to the potentially damaging nature of a jam like this and the difficulty of removing tape afterwards. (Usually the VCR will work fine...but using my VHS-C adapter revealed a problem with the source spindle. After an initial error occurs, the machine stops. After cycling power again to eject, it jams the shuttle and back tension regulator....and once that happens, it breaks down on playback and jams on every eject attempt until it's "fixed." I "fixed" it once before by magic and got it working again with regular tapes, but trying the VHS-C adapter again caused the jam once more, and I'm trying to understand what's going on this time..)

Thank you for your time!

On Apr 14, 10:04*am, Mike S wrote:
Hi,
I'm a total beginner, but I have a pretty simple VCR issue that doesn't appear to be covered in Sam Goldwasser's VCR FAQ (http://www.repairfaq.org/sam/vcrfaq.htm) or David T. Ronan's Practical VCR Repair, based on the skimming I've done.

When I'm stopping or ejecting a tape, my back tension regulator takes too long to move out of the way, and the left shuttle assembly gets blocked on it - and pins it in place - on its way back to the front of the VCR. *Basically, the two parts end up jamming each other, so neither can move, and it screws up the timing of the two shuttles as well as the gears underneath slip teeth.

What exactly is the mechanism that is supposed to make the back tension arm retract away from the full erase head and toward the tape door? *Is it supposed to sit passively while the left shuttle assembly pushes it back toward the front, or is the VCR supposed to apply power to explicitly move it out of the way? *If the VCR is meant to explicitly apply power, what controls the timing of this?

I half-expected this issue to be a common cause of jams and thoroughly covered by VCR repair resources, since the back tension arm literally crosses the path of the left shuttle assembly, but I haven't found anything about it yet. *I can't imagine I'm the only person in the world who has ever had this happen to them.

My VCR has other issues that bring about this behavior initially, but this is the most pressing problem due to the potentially damaging nature of a jam like this and the difficulty of removing tape afterwards. *(Usually the VCR will work fine...but using my VHS-C adapter revealed a problem with the source spindle. *After an initial error occurs, the machine stops. *After cycling power again to eject, it jams the shuttle and back tension regulator...and once that happens, it breaks down on playback and jams on every eject attempt until it's "fixed." *I "fixed" it once before by magic and got it working again with regular tapes, but trying the VHS-C adapter again caused the jam once more, and I'm trying to understand what's going on this time.)

Thank you for your time!

Sony broadcast tape transports have issues with lubricants drying
out / thickening up which causes problems similar to yours. The cure
is to disassemble the component, clean out the old junk and re-
lubricate. Since their lubricants were bad to begin with I don't use
Sony lubes. Nye Oil II is a vastly better light machine oil. A 2 oz.
bottle is about $9. Sony SGL grease can be subbed with Nye Rheolube
363F but that stuff is expensive. Do NOT use Lubriplate as it's even
worse than SGL as it separates. And whatever you do do NOT use WD-40
for ANYTHING in electronics.

G²

On Saturday, April 14, 2012 3:37:14 PM UTC-4, wrote:
On Apr 14, 10:04*am, Mike S wrote:
Hi,
I'm a total beginner, but I have a pretty simple VCR issue that doesn't appear to be covered in Sam Goldwasser's VCR FAQ (http://www.repairfaq.org/sam/vcrfaq.htm) or David T. Ronan's Practical VCR Repair, based on the skimming I've done.

When I'm stopping or ejecting a tape, my back tension regulator takes too long to move out of the way, and the left shuttle assembly gets blocked on it - and pins it in place - on its way back to the front of the VCR. *Basically, the two parts end up jamming each other, so neither can move, and it screws up the timing of the two shuttles as well as the gears underneath slip teeth.

What exactly is the mechanism that is supposed to make the back tension arm retract away from the full erase head and toward the tape door? *Is it supposed to sit passively while the left shuttle assembly pushes it back toward the front, or is the VCR supposed to apply power to explicitly move it out of the way? *If the VCR is meant to explicitly apply power, what controls the timing of this?

I half-expected this issue to be a common cause of jams and thoroughly covered by VCR repair resources, since the back tension arm literally crosses the path of the left shuttle assembly, but I haven't found anything about it yet. *I can't imagine I'm the only person in the world who has ever had this happen to them.

My VCR has other issues that bring about this behavior initially, but this is the most pressing problem due to the potentially damaging nature of a jam like this and the difficulty of removing tape afterwards. *(Usually the VCR will work fine...but using my VHS-C adapter revealed a problem with the source spindle. *After an initial error occurs, the machine stops. *After cycling power again to eject, it jams the shuttle and back tension regulator...and once that happens, it breaks down on playback and jams on every eject attempt until it's "fixed." *I "fixed" it once before by magic and got it working again with regular tapes, but trying the VHS-C adapter again caused the jam once more, and I'm trying to understand what's going on this time.)

Thank you for your time!

Sony broadcast tape transports have issues with lubricants drying
out / thickening up which causes problems similar to yours. The cure
is to disassemble the component, clean out the old junk and re-
lubricate. Since their lubricants were bad to begin with I don't use
Sony lubes. Nye Oil II is a vastly better light machine oil. A 2 oz.
bottle is about $9. Sony SGL grease can be subbed with Nye Rheolube
363F but that stuff is expensive. Do NOT use Lubriplate as it's even
worse than SGL as it separates. And whatever you do do NOT use WD-40
for ANYTHING in electronics.

G²

Thank you! I have the service manual, so I'll look into which parts need lubrication, and I'll use Nye Oil II as you suggest.

Nevertheless, the back tension arm does not appear to be particularly resistant to movement: I can move it very easily with my finger when it's not jammed, and the only resistance I feel appears to come from the spring...it just happens not to retract on its own when it counts. Do you know whether it's meant to retract actively (powered by electricity) or passively (pushed back to the front by the left shuttle assembly)?

wrote in message
news:1387820.1545.1334470225266.JavaMail.geo-discussion-forums@ynei5...
On Saturday, April 14, 2012 3:37:14 PM UTC-4, wrote:
On Apr 14, 10:04 am, Mike S wrote:
Hi,
I'm a total beginner, but I have a pretty simple VCR issue that doesn't
appear to be covered in Sam Goldwasser's VCR FAQ
(http://www.repairfaq.org/sam/vcrfaq.htm) or David T. Ronan's Practical VCR
Repair, based on the skimming I've done.

When I'm stopping or ejecting a tape, my back tension regulator takes
too long to move out of the way, and the left shuttle assembly gets blocked
on it - and pins it in place - on its way back to the front of the VCR.
Basically, the two parts end up jamming each other, so neither can move, and
it screws up the timing of the two shuttles as well as the gears underneath
slip teeth.

What exactly is the mechanism that is supposed to make the back tension
arm retract away from the full erase head and toward the tape door? Is it
supposed to sit passively while the left shuttle assembly pushes it back
toward the front, or is the VCR supposed to apply power to explicitly move
it out of the way? If the VCR is meant to explicitly apply power, what
controls the timing of this?

I half-expected this issue to be a common cause of jams and thoroughly
covered by VCR repair resources, since the back tension arm literally
crosses the path of the left shuttle assembly, but I haven't found anything
about it yet. I can't imagine I'm the only person in the world who has ever
had this happen to them.

My VCR has other issues that bring about this behavior initially, but
this is the most pressing problem due to the potentially damaging nature of
a jam like this and the difficulty of removing tape afterwards. (Usually the
VCR will work fine...but using my VHS-C adapter revealed a problem with the
source spindle. After an initial error occurs, the machine stops. After
cycling power again to eject, it jams the shuttle and back tension
regulator...and once that happens, it breaks down on playback and jams on
every eject attempt until it's "fixed." I "fixed" it once before by magic
and got it working again with regular tapes, but trying the VHS-C adapter
again caused the jam once more, and I'm trying to understand what's going on
this time.)

Thank you for your time!

Sony broadcast tape transports have issues with lubricants drying
out / thickening up which causes problems similar to yours. The cure
is to disassemble the component, clean out the old junk and re-
lubricate. Since their lubricants were bad to begin with I don't use
Sony lubes. Nye Oil II is a vastly better light machine oil. A 2 oz.
bottle is about $9. Sony SGL grease can be subbed with Nye Rheolube
363F but that stuff is expensive. Do NOT use Lubriplate as it's even
worse than SGL as it separates. And whatever you do do NOT use WD-40
for ANYTHING in electronics.

G²

Thank you! I have the service manual, so I'll look into which parts need
lubrication, and I'll use Nye Oil II as you suggest.

Nevertheless, the back tension arm does not appear to be particularly
resistant to movement: I can move it very easily with my finger when it's
not jammed, and the only resistance I feel appears to come from the
spring...it just happens not to retract on its own when it counts. Do you
know whether it's meant to retract actively (powered by electricity) or
passively (pushed back to the front by the left shuttle assembly)?


++++

Could a gear train/ rack or the mode switch have jumped a tooth, look for
alignment marks or holes in gear wheels etc, maybe in the manual. If 2 or
more teeth then usually a fully corrupt system but just one tooth and can
get intermittant good/ bad operation

On Sunday, April 15, 2012 3:05:26 AM UTC-4, N_Cook wrote:
wrote in message
news:1387820.1545.1334470225266.JavaMail.geo-discussion-forums@ynei5...
On Saturday, April 14, 2012 3:37:14 PM UTC-4, wrote:
On Apr 14, 10:04 am, Mike S wrote:
Hi,
I'm a total beginner, but I have a pretty simple VCR issue that doesn't
appear to be covered in Sam Goldwasser's VCR FAQ
(http://www.repairfaq.org/sam/vcrfaq.htm) or David T. Ronan's Practical VCR
Repair, based on the skimming I've done.

When I'm stopping or ejecting a tape, my back tension regulator takes
too long to move out of the way, and the left shuttle assembly gets blocked
on it - and pins it in place - on its way back to the front of the VCR.
Basically, the two parts end up jamming each other, so neither can move, and
it screws up the timing of the two shuttles as well as the gears underneath
slip teeth.

What exactly is the mechanism that is supposed to make the back tension
arm retract away from the full erase head and toward the tape door? Is it
supposed to sit passively while the left shuttle assembly pushes it back
toward the front, or is the VCR supposed to apply power to explicitly move
it out of the way? If the VCR is meant to explicitly apply power, what
controls the timing of this?

I half-expected this issue to be a common cause of jams and thoroughly
covered by VCR repair resources, since the back tension arm literally
crosses the path of the left shuttle assembly, but I haven't found anything
about it yet. I can't imagine I'm the only person in the world who has ever
had this happen to them.

My VCR has other issues that bring about this behavior initially, but
this is the most pressing problem due to the potentially damaging nature of
a jam like this and the difficulty of removing tape afterwards. (Usually the
VCR will work fine...but using my VHS-C adapter revealed a problem with the
source spindle. After an initial error occurs, the machine stops. After
cycling power again to eject, it jams the shuttle and back tension
regulator...and once that happens, it breaks down on playback and jams on
every eject attempt until it's "fixed." I "fixed" it once before by magic
and got it working again with regular tapes, but trying the VHS-C adapter
again caused the jam once more, and I'm trying to understand what's going on
this time.)

Thank you for your time!

Sony broadcast tape transports have issues with lubricants drying
out / thickening up which causes problems similar to yours. The cure
is to disassemble the component, clean out the old junk and re-
lubricate. Since their lubricants were bad to begin with I don't use
Sony lubes. Nye Oil II is a vastly better light machine oil. A 2 oz.
bottle is about $9. Sony SGL grease can be subbed with Nye Rheolube
363F but that stuff is expensive. Do NOT use Lubriplate as it's even
worse than SGL as it separates. And whatever you do do NOT use WD-40
for ANYTHING in electronics.

G²

Thank you! I have the service manual, so I'll look into which parts need
lubrication, and I'll use Nye Oil II as you suggest.

Nevertheless, the back tension arm does not appear to be particularly
resistant to movement: I can move it very easily with my finger when it's
not jammed, and the only resistance I feel appears to come from the
spring...it just happens not to retract on its own when it counts. Do you
know whether it's meant to retract actively (powered by electricity) or
passively (pushed back to the front by the left shuttle assembly)?


++++

Could a gear train/ rack or the mode switch have jumped a tooth, look for
alignment marks or holes in gear wheels etc, maybe in the manual. If 2 or
more teeth then usually a fully corrupt system but just one tooth and can
get intermittant good/ bad operation

Thanks for your response! It's possible it had already slipped a tooth, making the left shuttle early. That said, at this point I know it has slipped multiple teeth in the other direction: The jam caused tooth slips which significantly delayed the left shuttle. Thankfully the gears are still intact, but they'll definitely be realigned. I'm not confident the problem is an early left shuttle though for two reasons:
1.) You'd think the jam itself would fix that, since it slipped teeth in the other direction.
2.) I'm still not sure whether the back tension arm has a timed retraction, or whether the left shuttle assembly is just meant to push it toward the front whenever it moves. If the back tension arm is meant to move on its own at a certain time, then the timing of the left shuttle relative to the back tension arm matters a great deal. If the back tension arm is meant to be pushed by the shuttle, then the timing shouldn't matter, but the default position of the tension arm would (whether it's at an angle where it can be pushed, or where it's at an angle where it will jam). Knowing which is the case will give a lot of insight into what's actually going on when the unit jams! This is the question I most want to know the answer to, so if anyone knows how it's meant to operate in the first place, I would greatly appreciate a direct answer.

On Saturday, April 14, 2012 3:37:14 PM UTC-4, wrote:
Sony broadcast tape transports have issues with lubricants drying
out / thickening up which causes problems similar to yours. The cure
is to disassemble the component, clean out the old junk and re-
lubricate. Since their lubricants were bad to begin with I don't use
Sony lubes. Nye Oil II is a vastly better light machine oil. A 2 oz.
bottle is about $9. Sony SGL grease can be subbed with Nye Rheolube
363F but that stuff is expensive. Do NOT use Lubriplate as it's even
worse than SGL as it separates. And whatever you do do NOT use WD-40
for ANYTHING in electronics.

G²

BTW, is there any online store where Nye Oil II is available? If not, are there any retail chains that carry it?

On Apr 15, 2:54*pm, Mike S wrote:

BTW, is there any online store where Nye Oil II is available? *If
not, are there any retail chains that carry it?

The few times I've purchased Nye products was through TAI. You can
find this through the Nye website under "contact" small volume
orders

http://www.lubekits.com/

Select Nye products on the right and on the next screen top center
"Nye Oil II"

BTW I'm just now finishing up a 2 oz bottle first opened in 1997.
Also, the Sony field service techs in LA were getting Nye Oil II from
me because they know the Sony oil isn't that good and this stuff is
first rate. I find a medical syringe like for insulin shots works
great for very tiny drops which is usually all that's needed. I run
alcohol through the syringe to clean it of medicine.

G²

On Sunday, April 15, 2012 11:57:06 PM UTC-4, wrote:

The few times I've purchased Nye products was through TAI. You can
find this through the Nye website under "contact" small volume
orders

http://www.lubekits.com/

Select Nye products on the right and on the next screen top center
"Nye Oil II"

BTW I'm just now finishing up a 2 oz bottle first opened in 1997.
Also, the Sony field service techs in LA were getting Nye Oil II from
me because they know the Sony oil isn't that good and this stuff is
first rate. I find a medical syringe like for insulin shots works
great for very tiny drops which is usually all that's needed. I run
alcohol through the syringe to clean it of medicine.

G²

Perfect, thank you! It's a shame I didn't see them on the search engines I tried, because they offer great prices for something so hard to find. (Amazon for instance only sells a couple Nye oils through third party vendors, and the prices are through the roof.) I'll definitely pick up a bottle...I tend to think something else is probably causing my jamming problem, but my gut tells me this oil may at least help with the supply spindle problem that started the whole mess!

Meanwhile, I want to take the opportunity to ask the question that's haunting me again: Do you or anyone else know how the back tension arm is supposed to retract on this VCR model or in general? Is it supposed to sit passively and be pushed to the front by the left shuttle, or is power supposed to be applied to move it out of the way first before the shuttle hits it? It's killing me not knowing how this VCR is SUPPOSED to work...

On Monday, April 16, 2012 4:36:14 AM UTC-4, wrote:

Meanwhile, I want to take the opportunity to ask the question that's haunting me again: Do you or anyone else know how the back tension arm is supposed to retract on this VCR model or in general? Is it supposed to sit passively and be pushed to the front by the left shuttle, or is power supposed to be applied to move it out of the way first before the shuttle hits it? It's killing me not knowing how this VCR is SUPPOSED to work...

....OR...
Is the back tension arm supposed to be pulled in by the supply reel as it takes up the slack left by the retracting left shuttle...?

If that's the case, everything could potentially be traced back to that left spindle...

On Apr 16, 4:06*am, wrote:
On Monday, April 16, 2012 4:36:14 AM UTC-4, wrote:

Meanwhile, I want to take the opportunity to ask the question that's haunting me again: *Do you or anyone else know how the back tension arm is supposed to retract on this VCR model or in general? *Is it supposed to sit passively and be pushed to the front by the left shuttle, or is power supposed to be applied to move it out of the way first before the shuttle hits it? *It's killing me not knowing how this VCR is SUPPOSED to work...

...OR...
Is the back tension arm supposed to be pulled in by the supply reel as it takes up the slack left by the retracting left shuttle...?

If that's the case, everything could potentially be traced back to that left spindle...

have you looked at any working mechanisms to see how/what sequence
they work?

On Wednesday, April 18, 2012 12:33:16 PM UTC-4, hr(bob) wrote:

have you looked at any working mechanisms to see how/what sequence
they work?

Oh, of course! What I'm confused about is that the back tension arm is completely disconnected from the gears driven by the cam motor, which make pretty much everything else move except the direct-drive spindles and capstan.

The back tension arm is totally separate from all of the other moving parts in the machine. It's a thin metal arm that pivots on a tiny little rod connected to a thing in the front called the "STD ASSEMBLY" (standard assembly I guess?), which contains a tiny circuit board. The service manual indicates that the standard assembly needs to be placed pretty precisely (it gives detailed instructions for how to move it), and it says the voltage on a certain test point should increase linearly as the tension arm is pushed toward the front. This indicates that the system can at least measure how far the arm has moved, but...does that also mean it can apply voltage to move the arm toward the front with a tiny motor? I can't see any such motor, if it exists. Or is the arm meant to be pushed by the left shuttle or pulled by the tape as the source reel pulls tape in?

If anyone's interested in helping me figure this out, you can take a look at the service manual for the deck he http://www.digitalfaq.com/forum/vide...nual-sony.html
The forum requires you to make an account to download the manuals, but it's just a forum account, nothing shady (it's a bandwidth-saving measure, as well as a safeguard against the paywall service manual sites just downloading them all with a bot and reposting them on their sites for money).

Your question is kind of ironic though: Since the rest of the gears slipped teeth as a result of the jam (but probably not as the cause), I decided to take apart my unit and retime the gears according to the service manual. Unfortunately, I've apparently only made things worse. The mode gear, FR gear, and pinch communication gear are all perfectly lined up with the timing holes (although the mode gear and FR gear have a centimeter or so of un-notched, smooth-turning leeway in the unthreaded position, where it's tough to tell exactly how they line up, even with the holes...hard to explain). Manually cycling the worm wheel works fine (as long as I manually move the back tension arm out of the way with my finger), but the VCR keeps immediately timing out now trying to unthread when I turn the power on...even though I've double and triple-checked that everything's already in the default, unthreaded position. I doubt the mode switch is having problems, since it's electrical (it operates via optical sensors shining light on reflective paths on the back of the mode gear)...so clearly I've mistimed something, but I'm not sure how.

Two of the gears (the ones for the shuttle arms) look a little different than the service manual indicates, with different arrow locations and all, so the instructions for aligning them were a bit...unhelpful. Still, I think I have them aligned correctly, since there seem to be only three remotely sane positions for them relative to each other, and I chose the middle one. Besides, the cam motor doesn't even turn the worm wheel far enough for those to enter the picture before the VCR shuts off, so...I'm kind of at a loss. I'm tempted to buy another one just to see how it's supposed to work!

In case anyone ever has this issue, I figured it out:

The back tension arm is meant to be pushed by the left shuttle. It has a black plastic hook attached to the metal arm, which pivots on a rod and "grabs" the base of the full erase head (which stops the arm from moving further)...but it should not be allowed to pivot. It has a little notch on the bottom that fits into a hole in the metal arm. When the hook is fixed in place, its precise angle will allow the left shuttle to push the arm to the front. If it's allowed to pop out of place and pivot, the back tension arm will instead block the left shuttle.

I'm tempted to superglue the stupid thing.

Now I just have to figure out how to get the timing right again...maybe the pinch roller assembly slipped some teeth or something.