Marantz 4270 Power Mode Switch Question!

I see this thread is a year old but I recently picked up a 4270. I rebuilt the power supply and adjusted all voltages. It seems to work fine in 70 x 2 mode. The issue is when I slide the Front to Rear balance slider I get full sound out of right rear channel. It does look like at some point this switch was worked on. Was wondering if anyone experience this and or could suggest a possible fix. I'm trying to follow schematic but that is a real maze. Any help would be greatly appreciated. Thanks.20191117_172917.jpg 20191117_172921.jpg
 

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I don't know if the rear panel local remote switch could be an issue with this, but I would be sure to clean it and make sure it's in local.

This may be helpful, it's not my work, and I think it's based on the 4300 and 4400, it would be up to you to decide if it's applicable to the 4270.


Tom
 

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Thank you for posting the wiring info on the mode switch. The wire color is different on the 4270 compared to the 4300 although the wiring is the same to mode switch on the back.

In the mean time I may have found the issue of why the front to rear slider control is allowing a signal to come from right rear channel while in the 2 channel mode. I noticed that the slider was not able to be put all the way to the front position. While I had faceplate off I was able to use a small piece of 20 gauge solid wire to check for what was stopping the movement of front to rear slider. What I found was a small clip that seems to have come off internally. I removed it with a small set of curved hemostats.

I did find a pic of a disassembled slider control and confirmed that the piece I found is in fact part of the control and probably the reason why I have a signal passing to the rear channels in the 2 channel mode.

I did find a whole board with the correct p\n on the bay. I haven't swapped it out yet but plan on doing that after the holiday. It seems like quite a project getting to it. I figure I would recap the tone board when I remove it to get to slider control board. I will confirm the replacement slider is working before replacing and post the end result once completed.

I included pics of the piece I removed from my control and of a diassembled control that I found pics of on the net.

Thanks again Tom for the quick response.
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I just bought my second 4270, love the sound! The person I bought the unit from moved the rear mode switch while the unit was on.what can go wrong when this happens?
 
If all the switch contacts move properly in time with each other, everything is fine.
If they don't, it can cause damage to one (or more) of the power amps. It is recommended that the switch NOT be moved with the power on.

Tom
From the 4270 owner's manual:
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This also rules out using some speakers e.g. Polk SDA. (I know this is a little old, but I am looking for info on 4270s right now as I just got mine back from tech and am testing it out.)
 
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