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Marantz 1150 Power Supply Issue

A

AudibleHiFi

New Member
Working on restoring a very nice condition 1150 but am running into a couple issues, and really struggling to identify the source. Started by recapping P800 power supply with mostly Nichicon PW/PJ as well as a couple of Rubycon ZLJ caps of originals equivalent value. Also fully cleaned the contacts on the relay, removing quite bit of build up but ended up with smooth and clean contacts.

I ran in to issue when setting up idle current and power supply adjustments. I was getting <1mV reading from J701/J702 on both L/R. Full pot rotations would only change readout by .5-1mV at most.

When checking Power supply P800, I am reading -34V at J806 (-44V spec) and -16V at J808 (-22.6V spec). Connecting to J805(J816) & J810 and rotating R815(R816), I am only able to reach 34v max and ~28V min.
The 4 trimpots (R741, 742) on both P700 power amp boards have since been replaced with Bourns 2.2K trimpots, with no improvements.

I checked some P800 transistor values and the few tested (803,804,808,809) are reading below spec values, with only exception being an accurate -.6V at H808.

Any ideas on what may be going on or where I should be hunting? Thanks in advance.
 
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Pictures? We see things.

Did you replace any transistors?
Is there 12V on your voltage reference H811?
Are the voltages going in correct, what are the voltages in and out H803 and 804?
Are you sure another board is pulling too much current and dragging it down?

Remove the amp boards until you have correct voltages.
 
ivandezande said:
Pictures? We see things.

Did you replace any transistors?
Is there 12V on your voltage reference H811?
Are the voltages going in correct, what are the voltages in and out H803 and 804?
Are you sure another board is pulling too much current and dragging it down?

Remove the amp boards until you have correct voltages.
Click to expand...

Thank you for the guidance. I have not replaced any transistors. I will post some pics later today, as well as remove amp boards and gather the results from your suggested testing points.
 
AudibleHiFi said:
Thank you for the guidance. I have not replaced any transistors. I will post some pics later today, as well as remove amp boards and gather the results from your suggested testing points.
Click to expand...
Sounds good. Good luck and report back.

Once everything is sorted out, I really recommend changing all the transistors.
 
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