Technical Guidance Denon PMA 350

[GrahamFP]

Before I start ripping my Denon amplifier apart, I am sure my problem won't be unique.

Only when switching to phono, there is substantial loss of audio on the right channel. It isn't the deck/pick-up etc.

There is talk around about the protective cct breaker contacts being faulty. Q. Is there a separate contact for the phono o/p?

Has anyone a copy of the 350 (pre Mk 2) Amp? Any thoughts before I poke around? And whilst I am there any particular capacitors to change as a
question of 'general maintenace.?

Thanks in advance for any tips.

[walpurgis]

If it's only affecting the phono input it's unlikely to be protection circuits. Try some contact cleaner into the rotary input selector switch and work it a few times, it may just be dirty.

[Macca]

service manual here https://www.hifiengine.com/manual_li.../pma-350.shtml

for the SE version but should still help.

[GrahamFP]

Thank you Walpurgis and Macca. I have the cover off and I do have some contact cleaner and lubricant, which I will apply. Yes, I found that same manual download for the SE and have downloaded it. I will clean the selector switch first but it seemed to be more affected by the balance/bass/treble cut-out button, which does not seem to make sense. Sometimes (perhaps more often than not} everything starts off OK but then suddenly "That speaker's not working' (Some fragmented audio getting through). Will try the switch first anyway, nothing to lose there. But only on 'phono'. (I actually bought a replacement deck on the strength of it, so that's how I know it isn't the deck}! But the replaced deck can join up with it's old Sony parent Amp, which I gave to my daughter, the new one has it's own mains power lead! And yes I have been window shopping on Ebay for a better deck.

[Lawrence001]

I used to have a ghettoblaster that had the same issue, it was the source selector in that case.

[Macca]

could be any number of issues.

You could always consider getting a separate phono stage and solve the problem that way. Denon's built-in phono stages are good but could probably be bettered for not a lot of money with a second hand stand alone unit.

[GrahamFP]

Well the Denon is all back in harness and I have played a couple of LP's and all is well so far, so maybe the cleaner/lubricator has done the trick. Maybe the previous owner of the Denon didn't use the phono selection much and there was an oxidisation build up. Thanks, i'ts good to not be alone with a problem! (I was half hoping to change a capacitor or two:-)