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Marantz 1200b no audio

E

EWorld

Member
Hello AK,

I am in the process of restoring a Marantz 1200b, the unit came in dead and would not even power on.

I have recapped the entire unit and replaced the relay and resistors on the relay board. I only have 51.4v +/- and the relay will not engage.

No shorts on the drivers or outputs.

Anyone have any suggestions where to start?

Thank you
Ryan
 
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I had a problem with the Marantz amp-in jumpers causing oscillation so bad, my 1200 relay wouldn't engage. If you remove the jumpers, will your relay engage?

WZfhYt2.jpg
 
Might be time to pull out the output transistors in the 250 amp boards, to see if the relay will then engage.

Rgv92Cv.jpg


pnVIiod.jpg


Do your output transistors look original still, like above?
 
I'm sure someone else here has a better recommendation, but if it were me in this situation, I would remove both of the 250 amp boards from the circuit by removing the red or blue lead from the big caps, to see if the relay would engage, and to expedite the troubleshooting process.

B9CmxmD.jpg


EDIT: Are you using a current limiter, or a DBT with less than a 100W bulb for this?
 
Last edited:
MarantzRefrb said:
I'm sure someone else here has a better recommendation, but if it were me in this situation, I would remove both of the 250 amp boards from the circuit by removing the red or blue lead from the big caps, to see if the relay would engage, and to expedite the troubleshooting process.

B9CmxmD.jpg


EDIT: Are you using a current limiter, or a DBT with less than a 100W bulb for this?
Click to expand...

Ok with them removed the relay does klick on, and i am using a DBT. So it seems my issue may be on the output boards?
 
MarantzRefrb said:
I would see which of those 250's is causing the relay to not close, and then look close at the transistors on that board.
Click to expand...

Ok I tried just hooking up one side at a time, neither side will allow the relay to close. Outputs are not connected. ill remove the other transistors and check them just to be sure.
 
If you are sure there are no shorts anywhere in the amp, you might try to take it off the DBT and see if you get a different result.
 
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