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Marantz 250M - odd resistor values in circuit

quadmatrix82

quadmatrix82

AK Subscriber
Subscriber
Hi all, so I have been doing some preventative maintenance on my Marantz 250M which seems to work well however I have noticed the left channel has many resistors that test low in circuit compared with the right channel - when tested out of circuit all these resistors measure fine.

what could be causing these resistors to read so differently between the two channel?

This is a very late model board

Each channel has all new transistors which are matched

Some measurements below in circuit left channel vs right

R518 1.03k vs 1.3k
R514 1.65k vs 1.95k
R503 7.2k vs 8.2k
R10 3.6k vs 7.4k

There are others too but this shows the swings which seem pretty significant any ideas??
 

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If the measurements you've listed are in-circuit and the out of circuit values are correct then your resistors are likely fine. If the resistance was higher than spec while in-circuit then I would be suspicious.
I'm in the process of rebuilding my 250M. Can you tell me which transistors you have for your drivers? I can see 2N3583 for Q510, what was used for it's companion Q511?
Thanks,
Wade
 
quadmatrix82: Ok, so capacitor C520, 6800 PF, ± 10%, 400V. What type of cap is that? I can't quite make it out in the pic.
 
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