Beocord 3300 refurb – very low sound in left output

[987nick]

I’ve changed the belts; original ones were cheese wrapped round the wheels/pulleys.

Then, mechanics all working fine but no sound at all and output meter only showing maximum.  I changed the 2 x 220mf 10v capacitors on the Dolby board after I found Dillen’s suggestion from 2015.  All the other electrolytic capacitors on that board seem to test OK.

Next problem, I only get decent sound from the right channel.  The left is there if I set the balance to only left but it’s very feint and muffled.  I did think I had a break in the output lead where it comes out of the unit as wiggling that seemed to restore channel.  Therefore, I cut out the bad bit and resoldered the lead.  But, sound still bad.

I have the schematics and intend to work my way through all the left channel capacitors.  But, before I do that is there an obvious place to look?

 

Thanks

[Dillen]

Sure the problem is in the Beocord? Have you tried with a different amp or a scope?

Martin

[987nick]

Pretty sure it’s the Beocord.  If I plug it into the CD input on the Beomaster I get the same problem.  The CD3300 plays OK through the CD input, albeit for only 30 seconds but that’s a problem for another day.  The CD3300 also played OK through the tape input.

But, as I’m going to buy a 7 pin female to RCA anyway to run the Beogram through the main system I might as well get it now just in case there is a problem with the Beomaster.

 

 

[987nick]

Update – bought lead to plug into my Cyrus amp and nothing.  I tried it with the B&O CD player and tape deck using different amp inputs.  Turns out the lead is one to plug non B&O stuff into B&O amps.  Not really sure why it wouldn’t work and why it’s got a 7 pin female din at one end.  I’m waiting for the supplier to tell me where I’ve gone wrong.

If this helps with a diagnosis, I plugged it back into the Beomaster.  As I said, the left channel is very soft and hissy, the right channel is fine.  I did notice today the Dolby is  working on the left channel; turn it off very hissy, turn it on hiss is significantly reduced.

I checked the capacitors using a multi meter with a capacitance test function on the main board whilst it’s still in the machine.  I found the left channel caps are reading the same as the right channel.  I know you should check them after removal from the circuit to get a true reading, but if they measure the same would that indicate they’re OK?

[987nick]

Update on this issue.  I’ve got nowhere.

I’ve checked all the electrolytic capacitors (admittedly in circuit) and where applicable compared the left channel ones to the right channel.  Most of the readings were the same on both channels.  A couple differed so I removed these and checked them with a component tester, but they then tested OK.

I also rechecked my solder joints where I had to cut out a break in the DIN cable.  They are all OK.

My thinking is to now check the transistors, but I’ve not found many references to these failing.  Or, should I remove the left channel capacitors one at a time and check them out of circuit?

 

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