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Marantz 4300 right channel phono problems

Richs_Trains

Richs_Trains

Well-Known Member
Hey all,

I have a 4300 that I had not used in a while. I bought a repo WC43 cabinet and decided to mount it and connect it up. While going through the testing of all the functions, I found the right channel of the phono section sounds about 50% and has a static sound (like a bad transistor). I was hoping it was just something dirty in the controls, but everything sounds fine in all other modes. I have not disconnected it and looked inside, but it appears the P-400 is somewhat accessible and was hoping someone could point me in the right direction to cure this problem. I see from the SM that there are several transistors on this board and wondering if these are ones that commonly fail in Marantz receivers and if so, what are the modern replacements? I have a 6200 connected to a demodulator connected to the CD-4 input so I could just ignore the problem, but it will bug me until I actually fix it. When I got this unit, it was missing one amp board which I found online and I recapped the power supply, both power amps, and replaced the filter caps. It sounds great except for the phono problem. Anyone have experience with this or any insight as to what I should check when I finally disconnect it and open it back up? Thanks, Rich
 
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EastPoint said:
diodes too.
Click to expand...
I have disconnected the 4300 and removed it from the wood case. I want to have all the parts before I start and I have the caps and the transistors, but what should I replace the diodes with, I have some Vishay TZX15C-TR and if this are not correct, what should I order? Thanks, Rich
 
The two diodes are replaced with one 1N4148 each and the one that’s in the center is replaced with a pair of 1N4148 in series.
 
EastPoint said:
Yes, those are fine. They will probably fix it.
Click to expand...
Well, I replaced the 6 transistors, 3 diodes, and 3 caps and seems to be working fine on my test speakers, will hook it back up with the system when I get a chance (it's a heavy unit for these old bones). Thank you so much for your help! Rich
 
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