ordering components parts caps, transistors, diodes etc. I have run out.

Now I have installed the belts Martin sent me in the Beocord 5000. I'm happy to report that this sems to have cured all faults with this deck. As far as I can tell, it now functions exactly as it should. Some trimming might improve it even further but as it is, it sounds good recording new tapes and playing back old ones, made on other machines.

There is just one niggle and I suspect this isn't even a fault: The recording level is too low when connected to my Beomaster 901. Did I read somewhere that B&O changed the standard for this? If not, the fault could just as well be in the BM901.  

BeoGram 6000 CD4 repair complete - see the details with pics in the BeoGram section.

Menahem

Agent00soul wrote:

Now I have installed the belts Martin sent me in the Beocord 5000. I'm happy to report that this sems to have cured all faults with this deck. As far as I can tell, it now functions exactly as it should. Some trimming might improve it even further but as it is, it sounds good recording new tapes and playing back old ones, made on other machines.

There is just one niggle and I suspect this isn't even a fault: The recording level is too low when connected to my Beomaster 901. Did I read somewhere that B&O changed the standard for this? If not, the fault could just as well be in the BM901.  

I need to order belts for mine at some point. Mine will only open and close with assistance seems to want to play OK but it will only engage the tape mech for a second or two then it goes back into standy. Havent really spent much time with it. I have another beocord 5000 as well but have never even plugged it in to test it.

Eugene

Even after replacing the belts, you may still have that problem. The cause is that the rubber roller wheels have hardened, and aren't gripping the downwind axles. 

Solution - DeOxit Rubber Restorer.

Menahem

Agent00soul wrote:

Now I have installed the belts Martin sent me in the Beocord 5000. I'm happy to report that this sems to have cured all faults with this deck. As far as I can tell, it now functions exactly as it should. Some trimming might improve it even further but as it is, it sounds good recording new tapes and playing back old ones, made on other machines.

There is just one niggle and I suspect this isn't even a fault: The recording level is too low when connected to my Beomaster 901. Did I read somewhere that B&O changed the standard for this? If not, the fault could just as well be in the BM901.  

 

After doing some more testing, I have identified ine problem:

There is no monitoring during recording. So if you record from the aux input jack, you can't hear what you're recording.

I have followed the signal on the schematics and it looks like the input signal should be routed to the output during recording inside the Dolby chip. Any ideas? Is this normal?

Agent00soul wrote:

After doing some more testing, I have identified ine problem:

There is no monitoring during recording. So if you record from the aux input jack, you can't hear what you're recording.

I have followed the signal on the schematics and it looks like the input signal should be routed to the output during recording inside the Dolby chip. Any ideas? Is this normal?

I looked and measured some more:

There is a 4066 (IC 107) that mutes the output signal and this is controlled via two diodes: D107 mutes it during stop only and D106 mutes it during recording and record-ready (signal labeled "record silence").

Why should the output be muted during recording? It seems that unsoldering D106 would solve my problem.

Agent00soul wrote:

I looked and measured some more:

There is a 4066 (IC 107) that mutes the output signal and this is controlled via two diodes: D107 mutes it during stop only and D106 mutes it during recording and record-ready (signal labeled "record silence").

Why should the output be muted during recording? It seems that unsoldering D106 would solve my problem.

I removed D106 and now the Beocord works exactly the way I want. I can now monitor the signal that comes in on the AUX input, both during record-ready and recording.

Now the only remaining problem is that the recording output signal is too weak from the Beomaster 901. There are two ways to fix this:

1. Add an opamp inside the BC5000 that amplifies the signal.

2. Remove/short the 33k resistor that the BM901 has in series with the recording output.

The BC5000 has a 22 kohm imput impedance (the recording level pots) so removing the 33k resistor should more than double the signal level. I'm not sure this is enough, but it could be.
Modifying the Beomaster of course makes it non-compatible with old tape recorders but it's a simple task to add a 33k resistor inside those recorders. From a sound quality standpoint this ought to be better than to add an extra amplifier stage inside the BC5000, or what do you think?

Not B&O, but will be very usefull diagnosing faults in B&O equipment!

Not one, but two ESR meters, the circuits of which freely available on the net...

The top one seems to be working well, I am having teething problems with the bottom one at the moment. Hopefully the top one might look somrthing like this if I can master my plasticard skills...

I am still going to complete my digital ESR meter, but I have given up on printing the rather complex double sided board for now, so that can wait!

Didn't know Plasticard was still available! I remember doing some stuff with it as a kid 🙂