Das STUDER und ReVox Forum

Hello,

I am new to this forum and have a Studer A810 which I am repairing at the moment.

I am almost done, while now suddenly the machine won't stop immediately when pressing the STOP button.
The speed lowers to a very low speed for a few seconds and then finally stops.
It is happening on all of the 3 speeds, but the lower the speed, the shorter it keeps running.

The repair I did was following:
I have replaced a couple of elco's in the audio part and the anti spark capacitors in the capstan (C7) and spooling motor circuits (C26, C27 and C28).

After that the machine worked fine and I was ready to start the audio measurements, when suddenly the STOP did not function as it should do.

Does anyone has an idea where I should start looking for?

Software is 2586.

best regards,

Peter (Greentree)

Hello Peter,

have a look at the spooling motor control! The Tape Tension Sensor right must be plugged in the lowest connector P5.
The description of the original layout is wrong!
Check it and test it!

Greating Alfred

Hello Alfred,
Thanks for quick reply!

the connector is in the right place.
Actually the machine worked, and after I changed the caps C26, C27 and C28 in the spooling motor circuit it still worked.
The original caps were RIFA PMZ 2015, 0,47 uF / 150V. But these caps were completely cracked. One was already open and I guess sparking as there was black dust on the pcb.

As I mention, after change of the caps the machine worked OK for about 2 days.
Then the STOP problem came.

Could it have to do with the caps change?
There were MP caps. I put Siemens MKH caps in.

Some detail on the STOP:
when hitting stop folowing solenoids come in action/release
- pinch roller goes away from tape
- brake come in action

- somewhat later the edit

The effect is more on a larger reel than a smalller one.
on 26 cm diameter is about 6 seconds, while on 17 cm it is about 1 second.
Left reel is full.

best regards,

Peter

Hello Alfred,

problem solved!

I did what you asked for, and checked the spooling motor control board, including the electrical adjustments.
There were no errors.

Than I looked at the tension sensors settings, and they were a little off.
But after adjusting them, problem still existed.

Than I looked at the tape tension settings on the Tape Deck Controller PCB.
They were way off.
After adjusting these for Play, Back and Peak (chapter 3.4.5 of the A810 service manual), everything now works fine as it should be.

So still not sure if there is a relation to the change of C26, C27 and C28 on the spooling motor pcb.
Maybe it had a small effect.
For now I will not worry about that, as the machine is now working OK.

Thanks and best regards,
Peter.