Amplifier power cutting in and out

[reb78]

I recently got an old Denon PMA 1060 amp out of where it had been stored and set it up with some big speakers I had also stored. Its been paired with these for many years and worked perfectly.

The balance knob track is dirty but I cleaned the insides out with compressed air and its worked well for about 6 weeks.

Today I turned it on and the power keeps cutting in and out - i.e. the main power supply, not just power to the speakers. I can hear a relay clicking on and off and every time it does it it cuts the power to everything. It is hot where I am but only like 24C hot, the unit has air space around it and I dont have it on loud. It doesnt feel hot to the touch anywhere (unlike my laptop at the cooling vents by the fan).

Any ideas? Basically a relay keeps clicking on and off and cuts/starts the power as it does it.

The amp and speakers are rather nice so hoping for a simple fix.

 

[skotl]

I recently got an old Denon PMA 1060 amp out of where it had been stored and set it up with some big speakers I had also stored. Its been paired with these for many years and worked perfectly.

The balance knob track is dirty but I cleaned the insides out with compressed air and its worked well for about 6 weeks.

Today I turned it on and the power keeps cutting in and out - i.e. the main power supply, not just power to the speakers. I can hear a relay clicking on and off and every time it does it it cuts the power to everything. It is hot where I am but only like 24C hot, the unit has air space around it and I dont have it on loud. It doesnt feel hot to the touch anywhere (unlike my laptop at the cooling vents by the fan).

Any ideas? Basically a relay keeps clicking on and off and cuts/starts the power as it does it.

The amp and speakers are rather nice so hoping for a simple fix.

Oh that's interesting. A quick google shows that the Denon seems identical to my Kenwood 3020SE. Might broaden the search for a solution.

 

[skotl]

Schematic attached

The first thing I'd be doing is tracing the AC output from the transformer, checking the diodes etc. The schematic helpfully suggests that the DC side should be + and - 23V: do you have that?

If you want a comparison reading from any of the board, let me know and I'll check my Kenwood.

 

[reb78]

THanks for that - really helpful.

I will start checking. Fixing will likely be beyond me but there is a place locally who can solder small things into small boards (saved me hundreds on a hot tub PCB repair vs a new unit to replace the obsolete board!)

 

[reb78]

Update - searching for the kenwood led to a few posts talking about the input selectors. Basically, it made me twiddle some knobs.

Its not the power flicking on and off - the relay noise it made was like the relay that clicks when you turn it on, so I assumed it was power input.

Twiddling the speaker selection knob replicates the noise exactly - its set so you can select speaker pair A, B or A+B. I think I might have had it set to A+B but I only have speakers connected to the B pair output. Trying it now. This may have been a simple fix. I normally twiddle everything when something is faulty so not sure why i didnt try that first!

 

[reb78]

Feel silly now - its worked perfectly since i had a knob twiddle....

I think I must have knocked (or my son) had turned the speaker selection knob so it was set to both A and B but it has no speakers connected to A.

 

[Barking Mat]

Feel silly now - its worked perfectly since i had a knob twiddle....

I think I must have knocked (or my son) had turned the speaker selection knob so it was set to both A and B but it has no speakers connected to A.

Knob twiddling saves the day !

But not in public.