Restoring TEAC A3340S

[D_Zoot]

I've never tried 500k, it sounds like it might be a bit on the heavy side? Perhaps someone else can chime it. Barring that, you can always mix your own. Pick up some 100k and mix it with your 500k. There are ratio charts you can search for that will help you with mix ratios. I'd think if you end up 300-400k range you'd be good to go.

 

[Bohuweno]

I've never tried 500k, it sounds like it might be a bit on the heavy side?

Yes, it's pretty damn sticky. Excellent point about mixing it down though. I'll probably just get two fresh bottles of the same brand at 500,000 and 200,000, rather than mixing brands. I doubt that it matters, but it's no particular effort.

What I actually used when I did the flywheel bearing and the capstan bearing the other day was lithium grease. It seems to be fine for that section in terms of viscosity - I used it on another TEAC deck a few years ago. But the tube has no information on it at all, it's completely unmarked; I assume it came with some kind of packaging at the time, but that's long gone. As I've now gone the extra step of disassembling the capstan motor to lubricate with sewing machine oil, I'm wondering if it would be better to go back to the capstan assembly, remove the lithium grease, clean it all up, and re-oil that section with sewing machine oil. What do you think?

I've also been thinking, partly based on advice from some kind commenters here, that it would be best to just replace the dual capacitors. If I do that with two separate capacitors for each dual unit, would it be as simple as the following (and I hope this isn't a stupid question):

Is it possible to lash a pair of capacitors (using just regular old electrolytics) together with cable ties, and either directly or using a jumper connect one of the legs from each capacitor to a common solder pad? The schematic doesn't indicate any polarity for these capacitors, but would I be right in assuming that the negative legs share a pad in common?

 

[D_Zoot]

What I actually used when I did the flywheel bearing and the capstan bearing the other day was lithium grease. I'm wondering if it would be better to go back to the capstan assembly, remove the lithium grease, clean it all up, and re-oil that section with sewing machine oil. What do you think?

I've also been thinking, partly based on advice from some kind commenters here, that it would be best to just replace the dual capacitors. If I do that with two separate capacitors for each dual unit, would it be as simple as the following (and I hope this isn't a stupid question):

Is it possible to lash a pair of capacitors (using just regular old electrolytics) together with cable ties, and either directly or using a jumper connect one of the legs from each capacitor to a common solder pad? The schematic doesn't indicate any polarity for these capacitors, but would I be right in assuming that the negative legs share a pad in common?

I personally would re-oil the capstan shaft with a high quality machine oil, instead of the lithium grease. Oil is more appropriate for the bronze capstan bushing and the clearances involved. The lithium grease works well for the thrust ball bearing on the end though.

If the caps you are referring to are the motor run caps, they don't go bad often in Teac's. You can replace them with individual caps, but don't use common electrolytics, you must use AC rated run caps. Being AC caps they aren't polarity sensitive, either leg can be your common. Inexpensive "ceiling fan motor run caps" make great replacements.

 

[Bohuweno]

Thanks for the advice.

On the subject of the capacitor, I have seen some mention of it making a difference for this problem. But based on your opinion (and I think a few other people have said the same thing), and as replacements aren't the easiest thing to find, I'm going to leave the originals in for now; apart from anything, I'd prefer to see if oiling the motor is sufficient to eliminate the problem. And if not, I can always go back to the caps later.

 

[dhnash]

I'll probably just get two fresh bottles of the same brand at 500,000 and 200,000, rather than mixing brands.

This may be a less expensive option since you would only need to order the 300,000 cSt viscosity that you need rather than two other viscosities that you would have to mix:

https://www.amazon.com/Kyosho-30000...il+300000+cSt&qid=1564058741&s=gateway&sr=8-1

 

[Bohuweno]

Dhnash, thanks.

I actually found 300,000 eventually - it didn't come up at all in my Amazon Japan searches over the last couple of days, and then for some reason a few hours ago, there it was. It's on the way...

 

[Bohuweno]

Sorry to hear about the spring... and yeah you really do wanna find it before turning the thing on again, lest you accidentally short something to something else in a destructive way. I'd imagine it may be sitting on top of the audio boards for channels 1 and 3 (I believe 1 and 3 are the top boards). Not sure if you already know this, but if you lay the deck on its side you can swing out the bottom two audio boards - they're on a hinge. If you remove the feet on the bottom, the panel that wraps around the bottom of the deck and part of the back can be easily removed - that and the wooden side panels should be removed (they're easy/simple to put back on). I'd think this would enable you to find where the spring went, assuming it didn't lodge itself somewhere totally stupid.

Found it!

Yeah, it's been worrying me a few days, as I lost the spring while the deck was laid down on its front, it could have pinged anywhere inside. I wasn't sure if it had gone up or down. And I didn't have time during the workweek to start dismantling the machine until I found it. But fortunately, it ended up down the bottom, and when I took off the feet as you suggested and removed the bottom panel today, I located the spring. I'm not looking forward to putting it back on, but with the motor out, I've at least got more space to work with.

 

[Hot Sauce]

Nice, always a good feeling to find that sort of thing. Little springs and screws are a pain - I've always got a pair of tweezers (or even two) handy for that sort of thing. Definitely excited for when the deck is all working - I think you'll love it! I certainly like mine a lot.

 

[Bohuweno]

I've spent the last couple of weeks dealing with the capstan motor.

It's all relubricated, and the sponges near the bearing, which were pretty rotted, are replaced with new felt. Cleaned out all the old oil and added new. After reassembly, I had to take the motor out again because I was getting some noise ("chugging"), and I couldn't tell for sure if it was in the flywheel section or the capstan motor. Taking off and remounting the flywheel didn't seem to help. After running the motor only with the flywheel disabled, it was clear that nothing's wrong with the motor. I took off the flywheel again, recleaned, lubricated and put everything back together. The noise is finally eliminated, to the extent that looking from the front, I didn't even realize at first that the capstan was rotating. Progress there at least.

Something that's bothered me a lot has been correct positioning of the flywheel on the shaft. I've set it up so that I can feel about 1 mm of clearance (front/back play), but to do that, it's necessary to have about 0.5 cm of the shaft protruding from the rear of the flywheel bearing. It all runs well; the issue is the protective plate that goes at the back of the capstan shaft (I believe it's called the thrust plate). The problem is that when I mount this to the two posts, I can't tighten the screws fully, because it contacts the back of the capstan shaft too strongly. It slows down rotation; if fully tightened, it can probably stop rotation altogether. I have to really back the screws off, and then the plate itself of course is not held very firm. I have looked at this section repeatedly, and redone the mounting procedure for parts in this section again and again. Everything seems to be present and where it should be. Without the plate tightened in, but just held on fairly loosely by the screws, everything's fine. I can't work out what's wrong here.

Moving on from that, I played a tape, but the original problem is still there: the tape slows down 20 or 30 minutes in. For this, I think I'm going to have to track down replacements for the motor capacitor after all. As I've now got hold of some spring scales, I'm also going to do some of the tension checking specified in the service manual.

Just to check concerning the capacitor: do I need to match the exact capacitance values (2 uF and 0.8 uF)? I have yet to locate a perfect match, but I can get a 1.5 + 2.5 three-wire capacitor with a +/-5% rating. Something similar to this, but different spuriously named company:

https://imgaz2.staticbg.com/thumb/l...F/6A/a8a3f605-f0cc-4d82-a4d2-648ec1f9fa2f.jpg


I'll be doing this at a slower pace for the coming weeks/months, because I've got about 3 audio projects on the go at once, and this deck was something of an impulse buy that barged to the front of the repair/building queue. But one way or another I'm going to get this bugger working eventually...

 

[Bohuweno]

I seem to be getting closer to what I need for the motor capacitor: a 2-wire 450V 0.8 uF, and a 2-wire 450V 2.0 uF. So to modify my earlier question, is the higher voltage rating acceptable instead of using 250V versions, which I still haven't found at these capacitance values?

 

[D_Zoot]

I seem to be getting closer to what I need for the motor capacitor: a 2-wire 450V 0.8 uF, and a 2-wire 450V 2.0 uF. So to modify my earlier question, is the higher voltage rating acceptable instead of using 250V versions, which I still haven't found at these capacitance values?

Absolutely! The capacitance needs to be correct, but you can go higher on the voltage. The voltage spec indicates how high a voltage the capacitor will withstand. You can run a 450v cap at 120v.

 

[Bohuweno]

Absolutely! The capacitance needs to be correct, but you can go higher on the voltage. The voltage spec indicates how high a voltage the capacitor will withstand. You can run a 450v cap at 120v.

Thanks. That's going to make things a lot easier.

 

[Bohuweno]

It looks as if replacing the start capacitor with a 2 and a 0.8 uF has corrected the speed problem. I'm more accustomed to soldering smaller components (and solder pads), so getting the old capacitor off and the new ones on was not achieved very elegantly, but on first playback, I've managed to put through a whole tape without any issues. I used the same tape as before, and previously it would start slowing after around 30 minutes or so, towards the middle of the tape. I'll run it through a few more times in the next week or two to be sure it's stabilized and the problem has gone, then I can focus on other things. But at least the basic operation is now as it should be. And it's a relief that I won't have to - not yet at least - replace the reel motor run capacitors. Not a job I relish.

I still haven't worked out why the thrust plate restricts flywheel movement when I tighten the screws fully, so I'll have to go over that part again. That's been a bit frustrating. Must be something about the way I've mounted the flywheel, but everything seems to be as specified in the service manual and described by other people. A job for another day...