The Workbench

Re: Beocord 5000 (4922) no playback/record

Dillen — Wed, 02 Jan 2008 15:43:06 GMT

Yes, caps !

Good job

Martin

Re: Beocord 5000 (4922) no playback/record

Ben — Wed, 02 Jan 2008 13:51:32 GMT

Hi Martin

Thanks for your words of encouragement.

I got my old 'scope out of storage and found that the signal was getting lost on the Dolby PCB, underneath the main PCB.

I traced the fault to the HA12038 Dolby IC's. They weren't outputting the 7v signal. The only common component on the 7v line is C3, 220u 10v capacitor. This had failed short circuit and was preventing the 7v line from powering up.

I Installed a new one and everything is great!

Thanks,

Ben.

Re: Beocord 5000 (4922) no playback/record

Dillen — Sat, 29 Dec 2007 04:07:36 GMT

Welcome to Beoworld !

First make sure that the record source switch (near the MIC socket) is set correctly.

If still no luck, you need to measure around a bit and follow
the signal on an oscilloscope to find where it gets lost.
The record/playback relay and Dolby relay if present in your machine
are known trouble makers.
Aging capacitors can also cause strange faults.

Martin

Beocord 5000 (4922) no playback/record

Ben — Fri, 28 Dec 2007 17:40:52 GMT

I have the 1980's beocord (4922 I believe) which developed a couple of faults when I came to use it recently;

There is very feint distorted playback heard through one channel when I crank the volume up. The VU meter for that channel shows the first level flickering.

Upon recording, no level is shown through the meters even when the record level is set to 10 and no sound is recorded.

I checked for the problem of the burned out power resistor at the front right of the main board. The resistor measures 5 or so ohms and I have 5v on one of the legs, and a little bit less on the other side, so it looks ok.

I also checked for the relevant voltages on the output for the power supply board, and all appears correct +/- 200mV or so.

My eyes are going square from staring at the service manual... please help!