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Marantz Model 33 input issue

Raccoon1400

Raccoon1400

Super Member
This model 33 preamp has a bleedthrough problem. Not just a bit either, I hook a CD player up to aux, the signal only gets a bit quieter when I switch inputs. Anyone seen this before? What can do this?

Also, if anyone has a schematic, it would be a great help.
 
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I had a very similar issue with a Marantz 1200 integrated, which has a preamp section very similar (if not identical) to the Model 33. Catrafter turned me on to some factory bulletins that we have available in the AK Database that deal with this fairly common problem. It involved some additions and subtractions of jumpers in the selector switch:

http://www.audiokarma.org/forums/showpost.php?p=5235466&postcount=29

If you don't see any bulletins regarding the crosstalk issue for your 33, look for some on the later-produced 3300, and if all else fails, look at the service bulletins for the 1200. Hopefully this'll get you on the right track for a fix - good luck!
 
I found them for the 1200. Now to figure out how close that fix is to the fix for this unit...

But looks like there is a nice picture in the bulletin (for the 1200).
 
So if I hook something to an input, I can hear it through all the other inputs except the one it is supposed to be in. Doesn't quite fit the problem described in the service bulletins, which says the crosstalk will be heard through phono when using high level inputs.
 
I had some very low level cross talk in mine. I cleaned all the switches and pots and now its gone.
 
Any ideas? I have none. And I can't find the correct SM. The SM for the 1200 has a couple service bulletins about crosstalk, but it isn't quite the same issue, or quite the same unit.

If I hook something to an input, I can hear it through all the other inputs except the one it is supposed to be in.
Also the tape selector works fine.
 
Figured this out! There was a bad solder for a ground connection. When an input is not selected, the switch was supposed to short it to the ground. But it was shorting to the ground of the board, which wasn't connecting to the RCA jacks ground.
 
There was still some crosstalk.

I ended up running another ground wire from the input jacks ground to a spot closer to the selector switch. This brought the crosstalk to zero. For some reason, there is still a bit with my ipod as a source (though very small), but none with my CD player or anything else.

I'm just fixing it for someone, but I hooked it up to test with the power amp in a luxman L-100 integrated, powering a pair of ditton 33.
 
Very good news

Raccoon1400 said:
Figured this out! There was a bad solder for a ground connection. When an input is not selected, the switch was supposed to short it to the ground. But it was shorting to the ground of the board, which wasn't connecting to the RCA jacks ground.
Click to expand...

I have been chasing cross-talk issues with my 3300 for as long as I've owned it, and finally I have a good starting place to look for this problem. Grounding problems!

Thanks for your input about your experience!

Mike
 
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