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Sony TC-630 reel to reel

T

TedStriker

New Member
Greetings folks! I just picked up a Sony TC-630 reel to reel for twenty bucks so I could try my hand at working on these things. The problem with it is that it was playing very slowly. I replaced the motor run capacitor and oiled the motor, idler wheels, pinch roller, and capstan. It now plays perfectly at the correct speed!
But, I have two problems:

1. When I press play, the left reel seems to take off a little faster than the right reel (or maybe it's the right reel taking off slower)... this lasts about a second, but it's enough to make tape have slack on the left side, allowing the tape sensing wire (actuator?) drop down... then the right reel "catches up" and pulls the slack tape back up, engaging the tape sensing wire, and then it runs fine. So the result is that it starts playing, slows down a bit, speeds back up, and then plays normally at the correct speed. This all lasts about a two seconds or so. No problem when starting a tape, or between songs, but sounds bad when I have to stop a song in the middle and restart. Plus, the main thing... I know this isn't how it's supposed to function.

2. When I fast forward, then stop and press play, the tape will slide out from between the capstan and pinch roller, causing everything to speed up. But when I stop it, then press play again, it's like the tape gets back into the correct position, and then it plays normally. So any time I have to fast forward, I have to stop, play, stop, then play... and then it runs fine.
I've already cleaned the tape path, heads, capstan, and pinch roller... but maybe not enough??

Any ideas?? This is the first RTR I've ever worked on, so any help, ideas, thoughts, comments, etc. are welcome and very much appreciated!

Thanks!
Chad
 
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Hello and welcome to audiokarma.
Sounds from your post that you have ability to work on electronics.
The problems you describe are a common problem with these old Sony's with idler wheels.

You can go to hifengine.com establish an account which is free. Go to library, up on top of the page and scroll down under "reel to reel and look for your model number. For this one I would pick the (service manual IMP scan. Save this to your documents.

From what you explained it sounds like the back tension needs to be set. Your going to need some spring scales for this. Like any other hobby, your going to need some tools. :D
Hope this helps and again, welcome. :thmbsp:
 
Thank you for the welcome and the help!

I have verified that it is the back tension causing the trouble. I pressed a finger lightly against the edge of the supply reel to provide my own back tension, and that solved both problems.

Unfortunately, on this model, there is no way to adjust the back tension that I can see from looking at it, and from reading through the service manual.

As another poster indicated, which I verified by opening it up, the back tension is provided by a brake shoe that presses against the reel table. When in STOP mode, the shoe is pressed up against the reel table. But the felt (or whatever material it is) on the brake shoe has worn down over the years. So when I put it into PLAY mode, and the shoe pulls slightly away from the reel table, the felt has worn down enough to where it is no longer making contact with the reel table at all.

I'm going to try adding to the felt, or replacing it, so that it is thick enough to still make contact with the reel table when in PLAY mode... thus providing the back tension.

Thanks again for the help!

-Chad
 
Update: I did replace the brake pad material and that solved the problem!

Now then... it doesn't record correctly.
I have plenty of input signal, and the erase head is erasing correctly, but on playback, or monitoring the tape while recording, you can BARELY hear the song, and it's in only one channel, and it's a bit garbled sounding.
The tape path and heads have been cleaned.

Any ideas?

Thanks!
 
Clean and exercise the record slide switches. They are located on the record board inside the unit and are attached to the red record levers via linkages. Spray their contacts liberally with contact cleaner and exercise the heck out of them. All signals go through these switches and they are notorious for causing problems like that.
 
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