Marantz PM4400 Amplifier

seanww69 · 5th August 2007, 02:25 PM

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
Sean

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.

Thanks
Sean

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.

-Chris

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
Thanks
Sean

anatech · 6th August 2007, 03:40 PM

Hi Sean,

Quote:

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.

-Chris

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

Kind regards,

/tricomp

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

Regards
Sean

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

Hi,

No problem.

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

Kind regards,

/tricomp

5th August 2007, 02:25 PM	#1
seanww69 diyAudio Member Join Date: Jun 2007	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 Sean

6th August 2007, 03:34 AM	#4
anatech diyAudio Moderator Join Date: Jun 2004 Location: Georgetown, On	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. -Chris __________________ "Just because you can, doesn't mean you should" © my Wife

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5th August 2007, 04:01 PM	#2
jaycee diyAudio Member Join Date: Apr 2004 Location: Norwich, UK	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.

5th August 2007, 04:08 PM	#3
seanww69 diyAudio Member Join Date: Jun 2007	Hi Thanks for reply no its not getting hot at all. I will have a look at the circuit to the mute switch. Thanks Sean

6th August 2007, 09:57 AM	#5
seanww69 diyAudio Member Join Date: Jun 2007	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 Thanks Sean

2nd September 2007, 06:42 PM	#7
tricomp diyAudio Member Join Date: May 2004 Location: Jutland	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 Kind regards, /tricomp

2nd September 2007, 07:00 PM	#8
seanww69 diyAudio Member Join Date: Jun 2007	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 Regards Sean

3rd September 2007, 05:03 AM	#9
jaycee diyAudio Member Join Date: Apr 2004 Location: Norwich, UK	tricomp, mind if i grab a copy of that service manual?

3rd September 2007, 11:56 AM	#10
tricomp diyAudio Member Join Date: May 2004 Location: Jutland	Hi, No problem. Give me your e-mail address and it'll be on it's way Kind regards, /tricomp

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