Marantz 2230 no right channel

ranukic

Active Member
Hello,

I have verified that the issue is not the P750 (R) circuit. I am thinking that it is somewhere in the P300 board but I am struggling on this one. with the volume turned up I get some leakage from the left channel but when I turn the balance all the way to the right the leakage is not there.

Any suggestions?

Thanks,

James
 
Is this unit a "b" model. P700 shows as power amp and P300 MPX board. Do you have a scope and generator? Are you getting signal out from the right Ch. AUX or tape out?
 
I had a very, very weak channel in a 1030 that was probably a bad, corroded leg on a cap. Tried lots of stuff but nada, the recap fixed the unit. Unsoldering the first leg of that one and it came out, leaving its pegleg behind.
 
I just checked checked and there is no sound from the right channel from AUX or Tape. I do not have a scope or generator but I do have a simple volt/amp meter if that helps?

Thanks, James
 
I ordered a 2 channel oscilloscope last night and should have it by the weekend.

Thanks,

James
 
I am finally getting back to this. After playing around and taking some measurements it appears the right channel is not out but it is not responding to the tone adjustments and produces an extremely loud output compared to the left channel. The left channel appears to be functioning correctly and is responding to the tone adjustments.

I also flipped the pre-out and main in signals and the issue follows the pre-out.


I took some measurements on the P400 board and noticed that the right channel saturates quickly when turning up the volume. I input a 400hz tone and I was able to create a square wave on the left channel but the right channel is completely out of control. I also noticed if I get too close to the R419 resistor a hum is sent through the right channel.

I took the following readings from the emitter leg from the diodes on the board all seem to be close to the manufacturers board specifications.
H401-27.98v
H402-27.96v
H403-3.25v
H404-3.34v
H405-.362v
H406-.324v
H407-12.81v
H408-13.46v

Any thoughts on what might be causing this?

Thanks,
James
 
I decided to take another reading comparing the left and right input signals to the P400 board and found that the right signal is messed up so the issue must be prior to this board. Going to look upstream further.
 
The Aux or Tape pass the signal along from the sources that are plugged into the receiver and should dump out the record out even with the receiver turned off. This is easily checked. Many old vintage receivers array of record out/in buttons (tape monitors) and various filter buttons have not been activated for really long periods of time. It is greatly possible that there are corroded contacts not allowing the signal to pass onto the preamp board.

There is also fuses located on the amplifier boards, but it sounds like the amp section is working. A little Deoxit 5 on all the moving switches and rotary controls might also help the dead channel kick in.
 
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