[987nick]

I’m diagnosing my Beocord 3300 model 2942 which has the left playback volume much lower and more hissy than the right hand channel. I’ve owned the unit from new and have never had any work done on it till now.

I’m working my way thorough the left and right Play Back amplifier circuits. With regard to the resistors I’ve found the following. The left channel resistors are 400 numbers and the right 200.

Resistors R201 and R401 are specified as 150k in the schematics, but actually read in circuit 11k and 112k respectively. R209 and R409 should be 68 ohms but read 28 and 68 respectively. Interestingly, R209 is actually 2 resistors piggy backed (running in parallel I assume) whereas R409 is one resistor. Did B&O run out of resistors?

Before I a) test them out of circuit and b) replace them, I’d like some guidance these may be part of the problem. Or, is it a pretty common situation components are changed in final assembly so differ from the schematics.

 

[Dillen]

Keep in mind, that if you measure across one component in a circuit, you may actually
measure others as well, because they are connected in some form.
Another thing is polarity; If you compare ohmic measurements make sure you have
the same polarity when measuring in both channels. A semiconductor may conduct current
in one direction and not the other, and that could give a difference in the readings.

Resistors wouldn’t be the first components I’d suspect.
And they will usually go open circuit or high in value – not low.

Martin

[987nick]

Thanks for that, I just wanted to check I wasn’t missing something before I start to remove components for off board checking. Those resistors are my starting point as all the others in that part of the circuit have similar values for left and right channels.

I will also be removing and checking capacitors as some of those are giving weird readings.

[Author]

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