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Setting DC Voltage levels on Marantz 2238B

redpackman

redpackman

Active Member
Over ten years ago fershure posted the following on the topic of setting DC levels on a Marantz 2238b:

"Greetings
I just tried to adjust my Marantz 2238B as per the attached instuctions. I think I got the power amp adjustments set. However I was unsure where to put the test leads on the resistors.
Is it like this? this is the first channel mentioned.

o
R765-
o Neg lead-

o
R763+
o Pos lead+ <--------resitor lead has a little loop here. Loop is absent on other leads. "


************************************

The Marantz service manual does not make clear where on the two resistors (R 765 and R763) the test leads are to be placed. R 763 has a loop which virtually invites the positive test lead's placement, (So that is where I placed the positive lead of my dvm), but it does not make clear which "side" of R765 the test lead is to be placed. As far as the negative lead's placement, fershure seemed to place it on the side of R765 that is closest to R763. That is the side I used in setting the DC level to 23 mV.

Is my assumption in reading fershure's diagram and interpretation of the service manual correct? It does make a difference. Why didn't Marantz make proper lead placement more clear?
 
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Be sure to turn the volume all the way down.
Connect your meter leads to the pair of points on the left. Adjust R731 for 23mVDC.
Connect your meter leads to the pair of points on the right. Adjust R732 for 23mVDC.
Polarity is not important.

Marantz service documents can be obtuse and full of errors.
Tom
2238B PA-filt (6).jpg
 
Tom, thank you. I'm afraid that is not the way I hooked it up. I hooked up my positive lead to the loops on R763 and in turn it's corresponding resistor in the other channel, but I put my negative lead on the leg of the other resistor that was CLOSEST to R763 and its counterpart.

So you're confident I did it incorrectly?
 
So, to be clear, I should place the negative lead of the digital volt meter on the resistor leg farthest from R763?
 
Power Off.
Volume all the way down
Meter set to read DC millivolts

Connect one of your meter leads to the end of R764 that has the loop in it.
Connect the other meter lead to the end of R766 closest to the center of the board.
Power on, wait a few minutes
Adjust R732 for about 23mV on the meter. POLARITY IS NOT IMPORTANT.
Power off.

Connect one of your meter leads to the end of R763 that has the loop in it.
Connect the other meter lead to the end of R765 closest to the center of the board.
Power on, wait a few minutes
Adjust R733 for about 23mV on the meter. POLARITY IS NOT IMPORTANT.
Power off.
Disconnect meter leads.
You are done.

Tom
 
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