ARCHIVED FORUM -- March 2012 to February 2022READ ONLY FORUM
This is the second Archived Forum which was active between 1st March 2012 and 23rd February 2022
Still trying to work out issues on my new Beocord 9000. It plays tapes normally, but the issue i'm stuck on is with the audio in for recording.
The Right side works normally but the Left side record level is not working. I've tested the left slide pot and its good, I've re-seated all connectors. When I move the Right slide pot while receiving audio the meter increases as I raise the slide pot, as normal.
On the Left side, the meter shows no audio, but when I move the slide pot the meter goes to max then back down. It also does this with the din cable disconnected and the right side does not do this. I've checked the continuity of the din/line switch, searched for broken solder joints, nothing changes the symptoms.
Have you checked the potentiometer itself?Else OpAmps, trimmers and capacitors in the signal path.
Martin
Ordered an opamp, will update if it fixes it.
the opamp was the issue, I have left side audio now in record mode.
For everyone's reference, IC4 on my unit is on a small board that is attached to board 2 with wires. The first set of schematics I downloaded from hifi-engine did not show this circuit. There is an alternate set of schematics on hifi-engine that does have this circuit.
While following the record audio signal I found the Left channel output of IC4, pin 7 was sitting at the rail voltage of -15v instead of an audio waveform.
IC4 is an opamp TI072CP, I replaced it with LME49720NA
Below is a picture of the small board and IC4
Good job!
There are two main versions of Beocord 9000, quite different in many ways (Dolby circuit, Motor circuit etc.).A couple of more or less undocumented modifications to both versions makes it difficult to find a servicemanual that matches 100%.