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Project: Marantz 1030

vmedia said:
Resistor readings (
R721 39.51 (lead facing side of board) / 3.04 (lead facing in)

R722 40.9 (lead facing side of board) / 21.2 (lead facing in)

Both resistors measure the same ohms in circuit
Click to expand...
Looks to me like R721 is bad. Pull one leg and check the resistance. Would also be nice to know emitter voltages for H701 and H702.
 
Then something downstream is pulling it down. Outputs are still a prime suspect to me. I would be trying to eliminate them, and if they pass, check every semiconductor in the path. For me, that means pulling and testing. Long shot -- check the solder joints on R721 and copper traces in that area with magnification.
 
Steven: Solder and traces on R721 look solid. I'll pull outputs if this goes much longer (not the easiest, and will want to rebuild the board when I pull it)

Dankik: Here are the transistor readings.

H707
E: 1.838
C: 1.067
B: 1.819

H705
E: 1.838
C: 3.077
B: 2.172
 
Hi all. Still trying to figure this one out. I pulled and check the right side output trannys and they both checked out. Used Atlas meter, so I'm confident they are OK.

I also replaced R713 / R731 as they looked pretty beat up. One leg actually came off (not sure if it was already off or not, but certainly was brittle). Replaced C715 / C715 because I could.
Pulled and checked H709 which was good.

Any next steps? I would love to determine the problem before rebuilding the P700 board.

Thanks
 
See attached updated schematic. Can you test transistors H705 & H707? Something is pulling down the voltage from R721. It is 39.5v on one side and 3.0v on the other.
"Replaced C715 / C715 because I could." Did you mean to say C715 and something else?
 

Attachments

Apologies - Meant to say C715 / C717.
Which also reminds me to ask about cap selection. Is there a guide to understand which caps are in the signal path?
I'll pull H705 & H707 and test.
 
You tested them all, might as well test H711 for completeness.
Did you also verify the polarity of C707 & C709?
 
I believe polarity on caps is correct (Pic attached) - I matched how the originals were installed (I received this amp with the bad right channel, before I replaced any components)
Thinking I need to eventually change out those in the signal path to some better caps for audio. Open to recommendations.
 

Attachments

  • 1030 P700.jpg
    1030 P700.jpg
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