Reel wobbling (Sony TC-399)

[Setiawan]

Hey guys,

 

I just found this machine in a back alley tonight, so I brought it home to check it out. I've never had a R2R machine before, so I'm still learning the ins and outs, even down to the basic operation. It was covered in quite a bit of dust, but it looks like it wasn't left out long enough to be rained on thankfully. It does look like it might have been kept in a slightly moist environment, but nothing I haven't seen on other audio equipment of a similar vintage. Other than that, it looks like it's in pretty decent nick.

 

I tried cleaning up the dust a bit before turning it on, and looks like it does run. Not sure if it'll actually put out sound yet, but one step at a time.

 

I noticed that the right reel holder/mount wobbles when it turns. It's not loose or anything, just crooked. I opened it up to see if there would be some easy adjustment to fix this, or if it could be easily reseated, but it's got me scratching my head a bit. See video:

 

https://www.youtube.com/watch?v=LD5xMpHcGfI

 

Anyone have any experience with this kind of problem?

 

Would love to eventually have this up and running smoothly and reliably. 

[pwstereo]

That looks like a bent shaft.

I'd disassemble it, remove the hub, pulley, etc till you just have the shaft.

Then you'll be able to straighten it. If you can't do it yourself an engineering workshop could do it for you.

Edited May 31, 2020 by pwstereo

[bob_m_54]

Looks like a bent shaft unfortunately. There is a service manual available here: https://www.hifiengine.com/manual_library/sony/tc-399.shtml

 

It appears to have a hollow shaft attached to the chassis, that seems to be fixed, with a second section that holds the rotating take-up reel table. It's not a great manual, but it may help if you decide to try and repair it.

 

Edit: Actually, from the diagram it is difficult to see exactly how it is assembled. You would have to determine which part of the shaft rotates, which is obviously where your problem is.

 

-------------------------

 

If you are unable to source a replacement, some gentle manipulation of the shaft or the attachment method, once it is removed may lessen the affect, but you could damage it even further.

 

That would be the reason the unit was discarded.

Edited May 31, 2020 by bob_m_54

[bob_m_54]

Not sure if this will upload.

tc-399_49-51.pdf

 

It did

Edited June 1, 2020 by bob_m_54

[Setiawan]

Thanks Peter and Bob. I'll take it apart again in the next week or so, and see if I can remove the take up reel table and straighten it out. I've been trying to bend it back while still assembled, but it seems no amount of force (that I'm willing to apply at least, which has been a lot so far) makes it bend.

 

Been taking a close look at the service manual (thanks again for that Bob). It looks like all that's really holding it in place is that final piece behind the chassis, marked E4 (a retaining ring), with everything else between that and the table being sandwiched in. 

 

Any tips on how I should be removing that ring? Don't want to end up breaking it, as I suspect I won't be finding a replacement any time soon.

 

Aside from this wobble though, the machine thankfully plays pretty much just fine. I cleaned the heads, tried playing the tape it came with, and I don't hear any problems with the output (the tape was some language-learning audiobook for Mandarin from the 80's. Certainly not what I was expecting haha). It's just a bit annoying to hear the tape brushing against the reel every rotation, and the uneasiness at the thought of the wear it's causing to the tape.

 

I'll have to apply some contact cleaner on some of the switches and pots though as they are a bit crackly.

 

Also the counter doesn't seem to move, but I'll look at that after the reel table.

 

Edit: picture of the machine

Edited June 2, 2020 by Setiawan

[pwstereo]

I looked at the exploded diagrams in the service manual. From what I can see the E4 (and other Ex parts) are E-type circlips.

Usually removeable with the corner of a small flat-bladed screwdriver. Insert the tip corner between the shaft and one of those relief cut-outs and twist to force the circlip to slide off the shaft. But put a rag or your finger tip behind the closed part of the circlip so it doesn't fly off and get lost. To re-install, either a screwdriver or needle-nose pliers, but again be careful of the springiness and slipping and hurting yourself, or it flying off into oblivion.

You'll be able to buy replacements, RS and other places sell them in a range of sizes.

Edited June 2, 2020 by pwstereo
Better image

[Setiawan]

Thanks for that, I was able to remove it and reinstall it like you described.

 

Even having the reel table isolated, it was a little difficult figuring out how exactly to make it straight. I managed to improve it though, and there is a lot less wobble than there was previously.

 

Also, it looks like the take up reel table wasn't sitting straight, regardless of the degree of the bend in the shaft. Another quick look through the service manual and it turns out you are supposed to insert a screwdriver into one of the gaps in the chassis, and bend it to adjust the angle of the reel table. I did this and it worked a treat!

 

 

I watched a few videos on people doing a deep clean/service of similar Sony machines (TC-377), which has inspired me to do the same in the near future. I've also ordered some new belts, as the current ones are somewhat slack (especially the ones for the counter, those are slipping entirely).

 

Contrary to what I mentioned before, there does actually sound like there may be a problem with the output - a hissing noise in the right channel. Still not entirely sure if it's the tapes I've been trying or the machine itself, but I'm leaning towards the latter. I may have to tinker around the playback PCB and perhaps replace some parts. I've done a visual inspection of them and it doesn't look like there are any leaking or bulging caps, but who knows. Besides, should be a fun project (having never done any maintenance on PCBs myself before, so a lot of learning ahead).

 

Anyway, thanks again!

[bob_m_54]

I was wondering if there may have been a foreign object between the friction disc and the reel trable to cause that wobbly. The shaft being misaligned WRT to the chassis, would only cause the reel table to sit at an angle, not wobble.

 

Glad to hear your having some success with it anyway.

Cheers.