Marantz DC offset

vintageboy

Chicago HiFi
I just got 2330 receiver and want to know the dc offset, I searched a lot online but couldn't find anywhere. I downloaded the manual but not in there!

On the speaker terminal I read:

- 031 for the right
- 030 for the left

is that good and how does the standard have to be? Does anyone know???
 
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Well I set the voltmeter to 200mv and I set up both channels to 15mv so I should be all done?


Were your first measurements 030 031 or .031 or 0.30?

Much difference in these measurements.
If offset is 15mv that's probably a little high.

If it's bias you are ok.
 
right now when it is set on 200mv it reads 15mv for both channels. No zeros before the number, when I switch it to 2000mv or higher than the o.xx appears!
 
I will just leave it like that because I don't have much knowledge and I don't want to mess up something. Thank you guys, now it is ready to go and blow my house!
 
Marantz usually states in it's servicemanuals, that the gear must show figures at max +/-50mV DC-offset. As you're allready told - adjust the DC-offset closest possible to Zero mV's (but within the +/- 50mV limit).
In post #6 you mention that you just put the DC-balance to 15mV's? - are you sure that you're not fiddling with the Bias adjustment at the same time?

regards
Freddy
 
Marantz usually states in it's servicemanuals, that the gear must show figures at max +/-50mV DC-offset. As you're allready told - adjust the DC-offset closest possible to Zero mV's (but within the +/- 50mV limit).
In post #6 you mention that you just put the DC-balance to 15mV's? - are you sure that you're not fiddling with the Bias adjustment at the same time?

regards
Freddy

Uh oh. You better post some pictures and what you did. Tweaking the bias trimmer without knowing the results is a very bad idea.
 
You see the ones in the red boxes, those are the ones that I moved very little so on the speaker outputs it shows 15mv

v7xg1x.png
 
What are their (V)R-figures? (typically written on the PCB) just where they are situated.

Nice pic BTW

regards
Freddy
 
You see the ones in the red boxes, those are the ones that I moved very little so on the speaker outputs it shows 15mv

v7xg1x.png

And you identified the trimmers in the service manual? If you correctly identified the offset trimmers, go ahead and get those figures down to 0 mV. Of course, turn on the amp for about 10 minutes first so it stabilizes before you make your adjustment. If you bumped the bias by accident, the heat sinks will be hotter.

Standard warning: See tech if you are not comfortable doing this adjustment.
 
I did a google search and I found that those are the ones! Today I was running it for about 3 hours and I checked if something was hot but nothing. The transistors were almost cold, probably because I was listening normal to it! I will double check to make sure those were the pots for the dc offset. I will lower it to 0mv
 
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