Project: Marantz 1030

[dankik]

The two caps that I can't verify from the picture are C711/C712 (green arrows). Please check.

 

[Steven Tate]

Double check the values on C715 and C717. The size discrepancy looks a little strange to me. Also, can you get the voltages on H703? When looking for some place pulling voltage down, I always look at resistors near the ground rail on the schematic. R753, R739, R757, R725, R719 should be checked to make sure none are shorted.

 

[vmedia]

I pulled that cap on the right side and it measured very low. I had to leave for a bit, but will replace that cap and if voltages are still off will follow your instructions. Including double checking tha cap values if the replacements.
Thanks.

 

[vmedia]

Replaced the cap and voltages are now up on the right side! Still no audio out of the right however. I'll provide updated voltages tomorrow.

 

[dankik]

Which cap did you replace?

 

[vmedia]

C711. Right side that you were not able to identify. C711 10uf 35v. Measured 3uf.

The small cap that you thought looked undersized is C717 22uf 35volt.

 

[vmedia]

UPDATED voltages. Audio output on right channel remains - still nothing on left.

J706: 21.24
J708: 22.62
J710: 48.20
J712: 23.60
J714: 24.10
J716: 22.51
J718: 23.54
J720: 0
J722: 0.59
J724: 0

J705: 31.13
J707: 32.48
J709: 48.20
J711: 32.20
J713: 32.20
J715: 32.20
J717: 32.20
J719: 0.45
J721: 0
J723: 0

R721: 44VDC on side closest to edge - 31VDC side toward middle of board

I can get back to it in a few hours if there are other readings that would help (I assume so)
Thanks

 

[vmedia]

Another update.
I was able to get the high voltages down on the right side of P700 by adjusting VR723.
Injecting 1K audio signal into this board is delivering sound on both channels!
I'll now focus my attention on the preamp board to see if signal is there and if so, where it is sopping!
Thanks for all your help.
I'll report back if I get stuck again.

 

[dankik]

Thanks. You need to remeasure the ECB voltages of H705, H707, H709, H711.
EDIT: Nevermind.... good job. See how the rest goes.

 

[vmedia]

Preamp had bad transistors. Sound from both sides now. Sounding pretty good!
Now I’ll recap the other side of P700 to match the right side. Update all preamp transistors and check caps/replace along the way.

I’m thinking I want to keep this one, so I’m toying with modding the output transistor connections so they plug in vs solder. I have some options in my parts stash that I may play around with. If I do, I’ll post some pics.

 

[vmedia]

The 1030 is slowly working it's way toward full operational. Thanks for all the help getting it to this point.

What I'm dealing with now is some low end distortion on the left channel (I have not fully recapped that side, so I'll hold off to see if the distortion goes away when I've matched the left side of the P700 to the right side)
I will also recap the preamp board. Transistors have been replaced on this board.

The current quandary is I'm not able to adjust the right side bias. It stays low with very little impact when adjusting the VR (R729) on that side (Left side adjusts fine). This is the case whether I'm measuring across one (R747) or both of the resistors. I suspect that this might have something to do with this being cap coupled, but I would expect both sides to act the same. Any advice on how to zero in on what's happening here?

 

[vmedia]

Been away from the workshop for a bit, but happy to report that everything is working as it should now. The bias setting issue was a combination of old Variable resistors and spotty meter connections. Thanks all for your help!