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Marantz 2252

F

freder29

Active Member
Could not find the SM for an european 2252

Need bias adjustment..

Are they the same as for the 2250B... below....?

2250B:
AUDIO ADJUSTMENT
1. Voltage adjustment
Connect a DC voltmeter between pin terminal 804 and 805, and adjust the trimming
resistor R806 for 35V DC.
2. Main Amplifier DC off--set alignment
Connect a DC voltmeter with 0.5 or 1 V range between the speaker terminals and adjust the
trimming resistor R707 for "zero" DC output on the meter.
Repeat the same procedure for the other channel.
Note: During this alignment no load should be connected to the speakerterminals.
3. Idle-current adjustment
Connect a VTVM between pin terminals 708 and 710. Next, adjust the trimming resistor
R719 so the VTVM reads10mV DC. Repeat the sameprocedure for the other channel.
4. Check DC off-set voltage aligned in the procedure 2 and if any DC output is observed on the
DC voltmeter, adjust the R707 again for "zero" output.
5. Phono-amplifier adjustment
Connect an oscilloscope to the TAPE OUT jacks and an audio signal generator to the
PHONO jacks. Place the selector switch in the PHONO position. Increase 1 kHz audio signal
gradually until a slight clipping on top of the sine-wave is observed on the oscilloscope.
Adjust the trimming resistor R408 for equal clipping level.
For the other channel adjust R409.
 
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Hello. I have a 2250B my maint manual says the same as your post above. One thing that was confusing in my case was when the procedure said.

3. Idle-current adjustment
Connect a VTVM between pin terminals 708 and 710. Next, adjust the trimming resistor
R719 so the VTVM reads10mV DC. Repeat the sameprocedure for the other channel.
Click to expand...

There were not test points like one would find. What I did find were the 708 and 710 written on the board and in the center of those were a transistor. When measured across this, I read initially 0.0 Vdc. I adjusted the voltage to 10mv using R719 to 10 mv. I then checked the DC offset and I could then adjust it down to .2v

Before that I couldn't adjust it down below 44mv. Only after the adjustment of that idle current was I able to make the DC offset adjustment.

On your unit, did you have TP or was it a small black transistor?

:music:
 
Thanks Freder. Yes it was the black transistor I measured across. BTW are you the person who restores Marantz. I contacted you about a year and a half ago. I was going to send in my 2250B but well, more pressing things gobbled up the moneys. :D The unit is still going. Only one light left on. The make-shift power button still works. Sounds just keep on coming good from it.
 
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