Strange fault with Denon PMA-355UK

smirny

Standard Member
Hello all,

I've got a strange, intermittent issue with a Denon PMA-355UK.

Most of the time when the amp is powered on the left channel doesn't work and increasing the volume with Source Direct on causes the woofers on the left channel to almost jump from their baffles until it goes into protection mode.
It also sends (I presume) this same current down the rca in/outs as when connected to another amp I managed to blow the speaker/shut down my phone (input) and saw the same woofer movement from the other amp/speakers (output) when controlling the volume on the Denon.
With Source Direct off it doesn't send this current out but still doesn't have any output on the left and will enter protection mode at around the same volume.

Now if I power cycle with the remote eventually it will work; both channels faultless even at high levels until I either change source or switch it off (standby or fully off) then the fault returns. I don't like leaving it on all the time as it never cools off.

What do you think the problem could be and would it be an easy thing to fix?

Just to add: I have tried it with nothing connected and it still did it, also tried recently lashings of contact cleaner with no luck.
 
Last edited:

AudioTechno

Novice Member
Hello smirny
I have just repaired one of this amp and as you have described the fault looks like it is a dryjoint on your amplifier and before it short the output stage you need to get it looked at or if you are good at soldering then look for the dryjoint near by rectifier diode which is mounted on the heatsink and next to both this rectifier is a same pack TO220 transistors it maybe dryjoints and look for the other copper plat supply jumper solder all their points.
Best of luck
AudioTechno
 

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