Need Marantz 1030 Schematic w/voltages

endervox

Active Member
I've been trying to work through an issue with a 1030. The SM/schematic on HifiEngine does not have voltages shown. This obviously makes troubleshooting more difficult.

I see in THIS thread someone apparently has a schematic with voltages, so one does apparently exist.

Anyone?
 
I was trying to get the amplifier adjusted (DMM across R747 and adjust R729 to 7.5mV) but am getting 0.0mV on both channels. I'm hoping to see where amplification is not happening by testing voltages at known points and working backward. I got this thing as a basket case and unfortunately did a restoration at the same time as the repair.

The outputs were blown in one channel so I replaced all with MJE15032G; since it's a bit of a pain to pull the amp board and the heatsink I did all at once..
 
Take a look at this.

http://www.audiokarma.org/forums/in...on-about-diodes-marantz-1030-schematic.67941/

Nakdoc knew that there were alot of bad components because that diode wouldn't blow up like that unless lots of current was going through it. This would be caused by blown output transistors and drivers. This amp has capactiors on the output to block DC from getting to your speakers. The reason for this is that this type of output stage doesn't have a positive and negative supply with an output swinging around 0V. Instead, it has a positive supply and ground, with the output swinging around 1/2 the supply voltage. There are 2 adjustments for the amp. R729 and R730 adjust the idle current, R723 and R724 adjust the Center voltage. Adjust the center voltage first. Measure the voltage on The collector of H001. Now adjust R723 so the voltage on the + side of C003 is exactly half the voltage you measured on H001. On the other channel, adjust R724 so the voltage on the + side of C004 is exactly 1/2 the voltage you measured on H001.
Now adjust the idle current. Measuring across R747, adjust R729 for 10mV. Measuring across R748, adjust R730 for 10mV. If you get ambitious, you might want to replace the output caps, C003 and C004 with 4700uF caps for better bass.

Tony
 
So I did exactly what was listed and did the centering voltage first but I still get nothing for idle current in either channel... So for centering voltage from the collector of H001 I get 52.5v, for both channels. I adjusted R723 and R724 for 26.25v, no problem. I'm rather confused...
 
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