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Panasonic SV 3800 Spills Tape, No play at all.
Old 3rd September 2019
  #1
Here for the gear
 

Panasonic SV 3800 Spills Tape, No play at all.

An interesting problem.

When I load the tape into the SV 3800, it seems to load fine, the guides come out and wrap the tape around the head and load around the capstan, looking ready to play (as I have experienced anyway previously when the deck was working well)

When I hit play, nothing happens, OR it starts spilling tape into the transport by turning the take up reel of the tape backwards. hitting fast forward speeds up the process for spilling the tape (which I suppose makes sense) rewind pulls up the tape but no reels at all move (the capstan pushes the tape) or the supply reel spills the tape at that point.

I will add upon tape ejection after the tape spilling (which is a pain and inconsistent) if it actually triggers the eject, that works well, the guides retract and the tray comes out and it gets a little tricky to fish the spilled tape out of the deck, but I can do it.

I've tried multiple times with multiple tapes and it seems to be a transport problem. Perhaps a logic problem? Not sure where to start with this one.

Any help would be appreciated.

Thanks
Old 3rd September 2019
  #2
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Richard Crowley's Avatar
You say "When I hit play, nothing happens". What does that mean exactly?
Is the head drum turning? Is the capstan turning? Does the pinch roller engage?

What is the condition of all the rubber parts?
Those fiddly and complex cassette transports are full of rubber tires, wheels, belts, etc. etc.
What is the condition of the lubrication on all the gears, bearings, etc.?

Do you have a service manual for your machine?
Are there replacement rubber parts still available?
The rubber parts of those old tape transports are a major weak point in attempting revival.
How much experience do you have repairing complex, miniaturized mechanisms like that?

Your presenting symptoms suggest that the take-up spool is not turning properly.
That would cause me (because I cannot see it) to think that some rubber part is faulty (or missing).
And that presumption is reinforced by your description of the malfunction of Fast-Forward and Rewind.

Those mechanisms were complex to keep in repair back 20-30 years ago.
These days you may be lucky to even find a source for necessary replacement rubber parts.
Old 3rd September 2019
  #3
Here for the gear
 

You say "When I hit play, nothing happens". What does that mean exactly?

this can vary. either the supply or take up doesn't turn, OR the supply turns, but in the opposite direction it should, spilling tape into the machine.

Is the head drum turning? Is the capstan turning? Does the pinch roller engage?"

yes. the drum is turning, capstan is pulling the tape so I assume the pinch roller is engaged.

What is the condition of all the rubber parts?
Those fiddly and complex cassette transports are full of rubber tires, wheels, belts, etc. etc.
What is the condition of the lubrication on all the gears, bearings, etc.?

I haven't gotten into that deep quite yet, but I know the pinch roller is fine and up until recently was working well, so maybe the rubber parts finally gave way.


Do you have a service manual for your machine?

yes

Are there replacement rubber parts still available?

not sure. But I will have to see what I can find online.

The rubber parts of those old tape transports are a major weak point in attempting revival.
How much experience do you have repairing complex, miniaturized mechanisms like that?

Not much for something that small.

Your presenting symptoms suggest that the take-up spool is not turning properly.
That would cause me (because I cannot see it) to think that some rubber part is faulty (or missing).
And that presumption is reinforced by your description of the malfunction of Fast-Forward and Rewind.

I wouldn't necessarily think that, because the supply and take ups are turning, but in the wrong direction. I was leaning towards a servo type of thing.

Those mechanisms were complex to keep in repair back 20-30 years ago.
These days you may be lucky to even find a source for necessary replacement rubber parts.

That's what I was concerned about, but still gives me a starting point to get into it deeper. Thanks.
Old 16th September 2019
  #4
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the problem has been found, seems the idler gear isn't properly making contact to the take up and supply tables....it's sluggish in moving back and both between the two tables causing the table pushed through by the pinch/capstan to spill. ...not sure how to fix it, as the idler gear is secured and locked into place. when not functioning. I have tried lubrication but that does little. Maybe something isn't aligned correctly or a spring is shot? the service manual really doesn't get into operation. At least the one I have.
Old 4 weeks ago
  #5
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Richard Crowley's Avatar
Sounds like dried-up lubrication grease on the part that moves back and forth.
You may need to disassemble it far enough to clean out the old grease and re-lubricate with new grease.
Just squirting oil in random places may cause it to drip onto parts that shouldn't have oil on them.
That is why they used grease, so that it wouldn't go where it wasn't needed.
Many of those tape transport mechanisms were a nightmare to maintain. Especially the smaller cassette/cartridge variety.
Good riddance to magnetic tape, I say. I had more than my fill of it in both the analog and digital tape era.
Old 4 weeks ago
  #6
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Quote:
Originally Posted by Richard Crowley View Post
Sounds like dried-up lubrication grease on the part that moves back and forth.
You may need to disassemble it far enough to clean out the old grease and re-lubricate with new grease.
Just squirting oil in random places may cause it to drip onto parts that shouldn't have oil on them.
That is why they used grease, so that it wouldn't go where it wasn't needed.
Many of those tape transport mechanisms were a nightmare to maintain. Especially the smaller cassette/cartridge variety.
Good riddance to magnetic tape, I say. I had more than my fill of it in both the analog and digital tape era.

I don't deny that, but you have new problems in the digital world with HD failures, unstable media that can easily corrupt, and costs of storage that are ongoing. It's more like trading one problem for another.

Going over the service manual I have, while it's pretty much useless for TSing, the exploded parts view lists a idler spring, seemingly very close to the wheel and the way it's been acting, slowly moving back and forth, almost sluggish, it's either what you say, grease build up that needs to be cleaned out, or the spring needs to be replaced. I'm a bit concerned about take it apart further, but I will be careful and document and take pictures as much as possible. trying to get lube into it currently is not doing anything for the idler, but I will say the load mechanism is now working better then it was previously, so that was a problem it seems also.
Old 4 weeks ago
  #7
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Richard Crowley's Avatar
Quote:
Originally Posted by scottsnailham View Post
I don't deny that, but you have new problems in the digital world with HD failures, unstable media that can easily corrupt, and costs of storage that are ongoing. It's more like trading one problem for another.
True. But here in the digital era, it is trivial to run a 100% redundant backup recording, and it takes seconds (and pennies) to create backup copies on diverse media. And keep offsite backups on a thumb drive in the back of your sock drawer at home.

Analog tape at least has some sort of "pleasant" soft distortion on overload (at least in some people's opinion). But the only reason to have a working digital tape machine of any kind is to transfer the data to a computer ASAP before the tape (or the machine goes bad.
Old 4 weeks ago
  #8
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+1 Richard.

Digital tape was a wonderful stopgap, particularly after oversampling became standard for ADC. But jamming all those bits into a tiny 4mm tape (or many more multitrack bits onto a DTRS 8mm tape). You had to have backup decks, because there was very little you could do in-house when they went down. My clients pretty much abandoned them for interchange ~2005, and all of the decks I was using then are long dead. Which means I have to pay $$ to a transfer house if I ever want to resurrect an old tape.

I'm working on a feature now where just my audio clips eat about 3 Gig. Imagine the time it would take to back and restore 90+ tracks up on linear digital tape. Now, high quality 1TB drives start around $50. I can keep totally separate archives of each step along the way. Backing up to a second drive takes just a minute or so, and Time Machine constantly makes a third progressive copy in the background.

If you're restoring that Panny deck just for fun, go for it. If you need to play back old tapes, it might be a lot faster and cheaper to locate someone with a working deck and transfer everything to a drive. Or two.
Old 4 weeks ago
  #9
Gear Addict
 

The Panny transport is a real PITA. It may be that you have a broken brake lever - those spindle brakes also have some sort of pad material that disintegrates, and there is another back tension pad/lever underneath the supply spindle. All those parts are unobtainium now AFAIK.

How are you observing the transport action? Without removing the loading mechanism and fooling the transport into thinking there's a tape in there, it's very hard to see what's actually going on. I unscrew the loader and set it to the side, still wired. Then you can fool the transport temporarily into thinking a tape is loaded - put tape on the left/right optical sensors and hold down all of the pin switches that detect tape type. At least for a few seconds, it will run like a tape is loaded, until it figures out the time count isn't moving.
Old 4 weeks ago
  #10
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Quote:
Originally Posted by GLouie View Post
The Panny transport is a real PITA. It may be that you have a broken brake lever - those spindle brakes also have some sort of pad material that disintegrates, and there is another back tension pad/lever underneath the supply spindle. All those parts are unobtainium now AFAIK.

How are you observing the transport action? Without removing the loading mechanism and fooling the transport into thinking there's a tape in there, it's very hard to see what's actually going on. I unscrew the loader and set it to the side, still wired. Then you can fool the transport temporarily into thinking a tape is loaded - put tape on the left/right optical sensors and hold down all of the pin switches that detect tape type. At least for a few seconds, it will run like a tape is loaded, until it figures out the time count isn't moving.


loading mechanism is off and tried with both an actual tape in it and and fooling the machine into thinking there is one there.

you've explain why it does shut down after a few seconds...I was sorta thinking that way, but you have confirmed it.

the pads are noticeably worn, but that's not the issue. the brakes work well in the operation based on what I can see. The problem is totally that the idler gear is not making contact with the supply and take up reel cogs. It stays in the middle between the two reels not lean towards either one and when the pinch/capstan starts pushing tape, it spills because nothing is moving the take up. I have to push it to one or the other. I have seen it operate when everything is normal, and it's not acting like it should.

This was an intermittent problem for some time, but not it just seems it's gone completely. Likely the spring.



I suspect the idler spring is the problem. I lucked out finding a source in Boston for the part and a couple more thanks to a search online. I've reached out to confirm they have that and a few more I found they have and move forward from there. I don't want to tear it apart more then once, so best to just replace it and move forward from there.
Old 4 weeks ago
  #11
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Quote:
Originally Posted by Richard Crowley View Post
True. But here in the digital era, it is trivial to run a 100% redundant backup recording, and it takes seconds (and pennies) to create backup copies on diverse media. And keep offsite backups on a thumb drive in the back of your sock drawer at home.

Analog tape at least has some sort of "pleasant" soft distortion on overload (at least in some people's opinion). But the only reason to have a working digital tape machine of any kind is to transfer the data to a computer ASAP before the tape (or the machine goes bad.

I would agree with that. I need the machine mainly as I have tapes I would like to digitize eventually. When I record my weekly radio show, I have about 5 machines rolling, 2 computers, reel, cassette and DAT I throw in for the hell of it. I can't easily duplicate what I do, it's totally off the cuff, so a fallback is preferred, and I've had the computers fail on me, so analog is better then nothing to work with, and often more reliable, even if I have to dub back into the PC.
Old 4 weeks ago
  #12
Gear Addict
 

Good, you are actually in there and not guessing.
I don't recall exactly what the center idler drive mechanism is, but I think there is just a drive gear underneath that moves the idler left or right by spinning in the appropriate direction. The whole assembly comes out IIRC when you remove the plate that holds the 2 brake levers and center idler down. A typical servicing would involve new brake levers, back tension lever, and pinch roller. I would just remove the brake/idler plate, remove the long spring between the brakes, and take a look. Bad lube could just be it; I am doubtful the idler spring has failed.

I have one here I need to clean up, but not sure when I can get it open.
Old 4 weeks ago
  #13
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Quote:
Originally Posted by GLouie View Post
Good, you are actually in there and not guessing.
I don't recall exactly what the center idler drive mechanism is, but I think there is just a drive gear underneath that moves the idler left or right by spinning in the appropriate direction. The whole assembly comes out IIRC when you remove the plate that holds the 2 brake levers and center idler down. A typical servicing would involve new brake levers, back tension lever, and pinch roller. I would just remove the brake/idler plate, remove the long spring between the brakes, and take a look. Bad lube could just be it; I am doubtful the idler spring has failed.

I have one here I need to clean up, but not sure when I can get it open.

I suspect it's likely grease is more goo then anything, but ultimately, as the parts seems to be affordable from audio proz, I might as well have what parts I can get now on hand. The pinch seems to be fine. Do the pads come new on the brake levers? I assume they do.
Old 4 weeks ago
  #14
Gear Addict
 

Pads came attached to the levers on OEM parts. I would be careful of NOS as the pad material might have deteriorated with time.

Edit: I opened mine up and yes, just remove the center plate (145) with 1 screw and the center idler gear assy comes right off. It just flops left/right depending on how it's driven. Mine has a bit of molygraph grease in there. Yours may have dried up.

Does Audioproz have more parts than their website would indicate? I would stock up on:

RXL0046 pinch roller
RXL0048 BT lever (supply back tension)
RXL0049 supply spindle brake
RXL0050 takeup spindle brake

Last edited by GLouie; 4 weeks ago at 06:00 PM..
Old 4 weeks ago
  #15
Here for the gear
 

Quote:
Originally Posted by GLouie View Post
Pads came attached to the levers on OEM parts. I would be careful of NOS as the pad material might have deteriorated with time.

Edit: I opened mine up and yes, just remove the center plate (145) with 1 screw and the center idler gear assy comes right off. It just flops left/right depending on how it's driven. Mine has a bit of molygraph grease in there. Yours may have dried up.

Does Audioproz have more parts than their website would indicate? I would stock up on:

RXL0046 pinch roller
RXL0048 BT lever (supply back tension)
RXL0049 supply spindle brake
RXL0050 takeup spindle brake

Not sure. I am going based on the website doesn't seem to have those parts, but as i'll give what you suggest a try, as I know where that screw is and go from there. Thank you for that.
Old 4 weeks ago
  #16
Here for the gear
 

Quote:
Originally Posted by GLouie View Post
Pads came attached to the levers on OEM parts. I would be careful of NOS as the pad material might have deteriorated with time.

Edit: I opened mine up and yes, just remove the center plate (145) with 1 screw and the center idler gear assy comes right off. It just flops left/right depending on how it's driven. Mine has a bit of molygraph grease in there. Yours may have dried up.

Does Audioproz have more parts than their website would indicate? I would stock up on:

RXL0046 pinch roller
RXL0048 BT lever (supply back tension)
RXL0049 supply spindle brake
RXL0050 takeup spindle brake

Well, thank you for your guidance, as I was a bit nervous initially pulling it off, but as you suggested, it was rather easy to pull off the plate and pull out the entire idler gear off without issues, same goes for putting it back in, despite it seeing to be involved.

As noted by other people previously, it's likely the cause was a very small amount of residue grease on the base of the idler. I cleaned it off and applied new lubrication and has seemed to resolve the issue.

After that was going I started playing with tapes and have determined part of the problem with the unit, was actually the tapes themselves, jamming and seizing the transport. These are older tapes, with multiple uses over the last few years, so it's fair to say they are a bit worm.

DAT tapes, it's been my experience, are rather flimsy in design, and can jam up. I suspected this, but with this issue, I am convinced I will have to use them sparingly. I had a NOS dat tape I put in it last night and loaded up fine, so while the idler was the machine, the tapes jamming up sort of through my troubleshooting off slightly.

Thanks everyone for all the help.
Old 4 weeks ago
  #17
Gear Addict
 

Good work!
This transport is among the worst at jamming IMO. I do believe that some older DATs may have developed a bit of stickiness, too. The BT lever under the supply spindle is a common culprit. When the pad on it wears down, the slight back tension it's supposed to provide is lost, leading to all sorts of loops and jams, such as when shuttling with the big knob back and forth.

I prefer the Sony PCM-R500 or higher; not perfect, but much more reliable. And only for transfers. I haven't considered recording on DAT for a long time.
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