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seanww69 5th August 2007 02:25 PM

Marantz PM4400 Amplifier
Hi all hope you can help, I have just acquired this amp from a mate but seems to have a problem when you switch it on everything works fine then after 20 seconds it switches itself to mute. Does anyone know what this fault maybe as i dont have a remote control could this be the problem
Waiting in anticipation to hear from the experts.
Kind regards

jaycee 5th August 2007 04:01 PM

Hard to say by this alone... does it seem to be getting very hot ?

Could just be a faulty power-on mute circuit... but without further testing it's not really possible to tell.

seanww69 5th August 2007 04:08 PM

Hi Thanks for reply no its not getting hot at all.
I will have a look at the circuit to the mute switch.


anatech 6th August 2007 03:34 AM

Hi Sean,
Check for DC offset on the emitter resistors that may trip the protection. I have seen leaky transistors in the protection circuit cause false tripping. They will be TO-92 style.

Do you have a schematic? With one we can give you more detailed help.


seanww69 6th August 2007 09:57 AM

Hi Chris

Thnks for your valued reply i have checked and have leakage in two areas which has dried up looks like glue
areas affected power supply part and r-ch l-rc
I dont have schemantic unfortunatley
Hope this makes it a bit clearer

anatech 6th August 2007 03:40 PM

Hi Sean,

Thnks for your valued reply i have checked and have leakage in two areas which has dried up looks like glue
That stuff is evil. Make sure you remove all of it. Inspect all component leads it may have touched as it can be corrosive as well.

This may solve your problems.


tricomp 2nd September 2007 06:42 PM

Hi Sean,

Did you ever fix it?

If you need the Service-Manual I have it. Give me a yell if you want a pdf-copy :D

Kind regards,


seanww69 2nd September 2007 07:00 PM

Hi All

Sorry not replied been on Hols, thanks for your offer of the service manual i have given up cleaned all the leaking caps but still no joy.

Am i am a blundering novice when it comes to more tech stuff so i have let it alone.

Thanks again gus for al your help


jaycee 3rd September 2007 05:03 AM

tricomp, mind if i grab a copy of that service manual?

tricomp 3rd September 2007 11:56 AM


No problem.

Give me your e-mail address and it'll be on it's way :D

Kind regards,


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