t.c. electronic 1210 Service Manual

[Potato Cakes]

Hello, Everyone,

I have a friend who has asked to see if I could help him repair his t.c. electronic 1210 as it's not powering up. I was getting +1V and -21V when I should be getting +/-15V. I replaced the rectifier diodes, regulators, and PSU and it still has the same voltage. Seems to be putting out the same voltage on the secondaries, but it I can now hear a gargling sound from the transformer after changing out the other PSU parts. It is board mounted and I don't know exactly where I can find a direct placement for it. However, when I used an external power supply to see if it would even power up, a resistor burned up pretty quickly in the middle of the main board, and I have no idea what that value is supposed to be. Does anyone happen to have a service manual for the 1210 that would have values for the component designations? I don't think I'm going to spend too much more time on this if I can't find one as if I run into an issue with the ICs I probably won't be able to find replacements for them that aren't fake chips.

Thanks!

Paul

 

[nashkato]

hi paul !
the burned resistor shows you where you got a shorted component .
external PS / lab supplies use current limiting for a reason .
i always measure ps rails for DCR before powering up .

sorry i cant help with the SM

if your friend , though wants to sell the 1210 , let me know

 

[Khron]

Might this help?

https://service-tcgroup.tcelectronic.com/tc1210/

 

[Potato Cakes]

Might this help?

https://service-tcgroup.tcelectronic.com/tc1210/

This is exactly what I was looking for. Thank you very much!

Thanks!

Paul

 

[Chandra]

Pull out the regulators and measure the ac voltages in the transformer secondary first. OK?
Leave it powered for an hour and make sure the transformer does not heat up too much.
Fix back the regulators, Disconnect the +/- 15 volts going to the circuit. OK?
Then look for shorted components.
Regards.

 

[Potato Cakes]

The transformer is fine, which is good because I was having a very hard time finding a suitable replacement that was small enough. I had already replaced both of the regulators before posting here, but I was still getting about -30VDC for the negative rail. I don't know if the only 7915 I had was bad as well. I wound up using an LM337 and doing a slight modification to the circuit. This gave me the proper +/-15V with the delay cards pulled. When I installed either of the delay cards in either position the positive rail goes down to about 3VDC. I don't know if when the 7915 when bad that it also fried some IC chips down stream. I wound up just ordering new ICs for the whole unit. If that doesn't work then I don't know what else to do. I think I'm close though.

Thanks!

Paul

 

[Potato Cakes]

First, thank you again, Khron, for providing the service manual. I managed to find the last problem. There was a tantalum capacitor on each delay card that went bad and was shorting +VDC to ground. Each cap was in a different spot on the card and took a lot of testing to find them. I don't know if the negative voltage regulator went bad first, but now everything is up and running. I also decided to upgrade the TL074s to TLE2074s. Replaced all the transistors on the delay cards for good measure as well. This will make a very nice Christmas surprise for this friend of mine as it had been sitting in his house dead for over a year.

Thanks!

Paul

 

[Potato Cakes]

I also uploaded the service manual to the technical documents for safe keeping.