Marantz 2235b- P800 PSU problem

[lesabb]

Hello all,

I'm quite the newbie at this so bear with me. I'm giving a go at a Marantz 2235B. It had intermittent sound on right side. Changed the vol pot. Changed the relay and recapped all the supply board due to leakage. Now I get no power from the 13V supply on the P800 board. Caps are working (at least charging up and holding). Look at the schematics and my issues are pointed. The bottom part working fine and getting 35V and other reads as advertised.

Another issue is that resistor R807 (150R/5W) is dropping the whole 41V! is that normal?

L

[SeanB]

Did you put C805 in backwards? That is the only thing that will short the rail out to 0V, all other faults will give you a volt or so on the rail. That or the capacitor is shorted or there is a solder whisker across it.

[lesabb]

Thanks Sean for pointing me in the right direction!! I found it! Somehow I shorted the cap to ground when re-installed the heat sink for the H804 transistor. Must have omitted some insulator or something. I feel good! 

L

[lesabb]

OK, so I got power to am/fm tuner and main amp. Problem is still there?! Unit will run for almost exactly 90min, then right side goes out. Should I try to bypass the main speaker switch? Can I use an AC meter to see if the signal reaches the main amp?

[moffy]

Follow the signal until it disappears. It might be easier if you could inject a tone from a signal generator into the main amp, leave out the am/fm tuner as a source, only debug 1 thing at a time. Yes you can use the AC Voltmeter to follow the signal.