Amplifier channel fault diagnosis/help?

setmenu · 11th February 2006, 03:13 PM

I wonder whether any knowledgeable soul here can help with diagnosing a developing fault with a commercial integrated amp.

The amp belongs to my other half and she has had the unit for the best part of a decade.
The amp in question is a Denon pma350II.

The audible symptoms evident at the right channel are an intermittent scratching sound similar to a poor connection.
The has now beginning to be accompanied by the sound cutting out for very brief periods of time.
Connections have been checked and speaker reversed to check them.

Opinions?

Many thanks

Mark

anatech · 11th February 2006, 03:22 PM

Hi Mark,
Start by removing the top cover. Tap the speaker realy while the set runs at a low volume with a non-conductive object. Not a rubber mallet!

If the sound cuts in & out, or just changes for the better or worse, you may simply need a new relay.

-Chris

setmenu · 11th February 2006, 04:10 PM

Hi Chris
Thanks for your suggestion.
I did as you said, but the relays seemed fine.

Cheers

Mark

anatech · 11th February 2006, 05:21 PM

Hi Mark,
I would be looking for broken solder connections after that. It's difficult to say since the amp isn't in front of me right now. Try operating each switch and control slowly to see if one of those are at fault.

-Chris

krmaudio · 12th February 2006, 05:03 PM

hi there,

have a look under the board, track side check area around level pots and around any input or output plugs / jacks / sockets, basically anything thats chassis mounted and is soldered to the pcb board/s

tap very gently with NON metalic object, small screwdriver handle sounds good, power supply rail fuses sometimes loose connection after years too....

hope this help a little,

11th February 2006, 03:13 PM	#1
setmenu diyAudio Member Join Date: May 2002 Location: UK	Amplifier channel fault diagnosis/help? I wonder whether any knowledgeable soul here can help with diagnosing a developing fault with a commercial integrated amp. The amp belongs to my other half and she has had the unit for the best part of a decade. The amp in question is a Denon pma350II. The audible symptoms evident at the right channel are an intermittent scratching sound similar to a poor connection. The has now beginning to be accompanied by the sound cutting out for very brief periods of time. Connections have been checked and speaker reversed to check them. Opinions? Many thanks Mark

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11th February 2006, 03:22 PM	#2
anatech diyAudio Moderator Join Date: Jun 2004 Location: Georgetown, On	Hi Mark, Start by removing the top cover. Tap the speaker realy while the set runs at a low volume with a non-conductive object. Not a rubber mallet! If the sound cuts in & out, or just changes for the better or worse, you may simply need a new relay. -Chris

11th February 2006, 04:10 PM	#3
setmenu diyAudio Member Join Date: May 2002 Location: UK	Hi Chris Thanks for your suggestion. I did as you said, but the relays seemed fine. Cheers Mark

11th February 2006, 05:21 PM	#4
anatech diyAudio Moderator Join Date: Jun 2004 Location: Georgetown, On	Hi Mark, I would be looking for broken solder connections after that. It's difficult to say since the amp isn't in front of me right now. Try operating each switch and control slowly to see if one of those are at fault. -Chris

12th February 2006, 05:03 PM	#5
krmaudio diyAudio Member Join Date: Sep 2005	hi there, have a look under the board, track side check area around level pots and around any input or output plugs / jacks / sockets, basically anything thats chassis mounted and is soldered to the pcb board/s tap very gently with NON metalic object, small screwdriver handle sounds good, power supply rail fuses sometimes loose connection after years too.... hope this help a little,