[brianlaing]

Hello all!
I got a donor amplifier / power board from Denmark to replace the faulty on I have in the US.
I now have regular audio but have noticed that while the CD player works fine, the doors and the cassette are slow. The doors don’t open or close all the way (a relay towards the back shuts the motors down) and the cassette sounds about 1/3 too slow.

One other thing – when I installed the donor / amp board there was no power to the cassette or door motors  I noticed that there was a T1A fuse missing from the donor board  I pulled one from the original board (checking it first to make sure it worked) and the audio came on as it should  I tested the other fuse and it was fine.  Just mentioning this since the fuses are fine on the board.  Muting works fine too

Any thoughts on why the motors seem to be slow (they were fine with the previous amp/power board)?

 

[Mark-sf]

I would check the 7V power supply section around TR19 and C10. If the fuse that was bad was T1A for the 5v supply there may be and issue with IC4 circuit or its zener.

[brianlaing]

Thanks for the tip! I actually decided to locate the parts on the original board (the one that controls the motor speeds correctly but only sound when you turn it up all the way). I noticed a missing resistor! So, tomorrow I’ll replace the missing resistor and swap back in the original board. Worth a try! 

• This reply was modified 1 year, 10 months ago by brianlaing.

[brianlaing]

Actually the missing resistor wasn’t the issue. In the original board the same resistor was removed, so not a coincidence. What ended up being the issue was a loose connector on a capacitor. The trace had lifted from the board for one of the legs on the capacitor, so I just added a jumper wire. Problem solved. The doors and cassette motors work at the proper speed. Always seems like something minor. 😉

[johnparker99]

I have the same problem with CD motor going slowly. Tape door motor is good. Do you recall where you found the loose connection @brianlang ?

[Dillen]

Lubricate motor bearings.
Replace belt.
Clean door tracks.

Martin

[auric]

PCB 60 which is the board mounted across the heat sink on the back of the unit.

There is one connector with a pair of wires. P80 or P81. Those powers the motors.

The traces on that PCB are very thin and fragile. Lots of cold solder joints and cracked/peeling traces especially where the connectors terminate and speaker muting relay.

Reflow the connectors and make sure the traces are not cracked.

[pepps]

brianlaing wrote:

Actually the missing resistor wasn’t the issue. In the original board the same resistor was removed, so not a coincidence. What ended up being the issue was a loose connector on a capacitor. The trace had lifted from the board for one of the legs on the capacitor, so I just added a jumper wire. Problem solved. The doors and cassette motors work at the proper speed. Always seems like something minor. 😉

Fantastic well deduced!

[Author]

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