Marantz 4220 questions on Ambience/SQ

[Richs_Trains]

Hey all, I know I said I would be here less since my wife passed on April 11th, but I had a unit that was slow in getting here (ordered it before she passed and it came today) and I was going to try to get it functional before I hang up my soldering iron. I have a 4220 quad receiver that, after some cleaning, functions correctly except for the Ambience/SQ selection. I have run it in both 2 channel and 4 channel mode and I get front and rear channels in all 4 channel selections except Ambience/SQ modes. When I switch to Ambience or SQ, I lose all channels, front and rear. I have cleaned the 2CH/4CH switch on the back, but it has not effect. I have not really looked at the schematic as things are pretty busy right now, but I was hoping one of the Marantz experts on this site may have encountered this problem and might have some insight as to what might be the solution. As always THANKS Rich

 

[bryans12v]

Stupid question but do you have the sq decoder plugged in? SQ only works with the adaptor.

 

[Richs_Trains]

I don't think the 4220 takes one, it looks like the decoder is built in P-300. It also loses the front channel when you chose 'ambience' which is the 4220 version of 'vari-matrix' without the variable control and that shouldn't happen. I think P-300 has a failure. Thanks Rich

 

[Nite1922]

Hi, Richs_Trains
If you trace the 35volt line to the SQ board, you should find a capacitor C330 220 @35v , probably shorted. Change to 220 @ 50v
There is a 56 ohm before this cap, check if it is open or really running hot.

 

[Richs_Trains]

f you trace the 35volt line to the SQ board, you should find a capacitor C330 220 @35v , probably shorted. Change to 220 @ 50v
There is a 56 ohm before this cap, check if it is open or really running hot.

Thanks, I will check it out and let you know. Rich