BeoCord 5000 Typ 4923, Play OK, but FF RW fail

[yachadm]

Greetings to all old friends.

It’s been many years since I last posted.

I have a BC5000 in for repair.

Symptoms:

1. Press PLAY – all OK.
2. Press FF – Rotates FF for 1/2 second, STOP 1/2 sec, then RW 1/2 sec, STOP 1/2 sec, RW 1/2 sec, etc indefinitely, until I press STOP
3. Press RW – Rotates RW for 1/2 sec, STOP 1/2 sec, RW 1/2 sec, etc indefinitely, until I press STOP

 

I hoped that it would just be a belt problem, so Martin kindly sent me a new belt and idler set, but unfortunately the exact symptoms remained.

It had previously been fully overhauled by me – new caps, poti’s, 10ohm PSU mod, etc, so that ruled out age-related problems.

I disassembled and reassembled the complete mech, as I have done many, many times before on these Vortex-mechanism decks, and found no problems.

I checked the keyboard contacts – all reading <1 ohm, and no contacts sticking.

Then I moved to measuring the voltages around IC1 upD8048. The results are shown in the attached image. That led me to conclude that IC1 is not defective.

I’m probably missing something, which maybe another member might pick up on.

Oh, and one other question – in the Schematics, there is shown a PAUSE function. But there is no PAUSE button on the machine. Is this meant to be the STOP button – that’s what I assumed?

Take a look at the attached file showing the voltage readings under various conditions, on IC1 upD8048 and P3 (the connector to the mechanism).

Menahem at CondorAudio in Jerusalem

[yachadm]

Here is a short film of the transport’s behavior during FF and RW

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