Can anybody suggest what might have destroyed my amplifier? Details inside...

[theartfulbadger]

Recently, my 1970s Panasonic SG-165 amplifier started giving me grief. First, I realised audio was only coming out of the right channel - then if I switch round the speaker wires at the back of the unit, the audio comes out of the left speaker, but quietly and distorted.

I don't know what might have caused this, although I recently started using a new configuration of decks with a mixer. The audio was channeled as follows:

Deck(s)>Vestax DJ Mixer>(adapter from mixer's RCA line out to headphone jack)>Aux Input to Amplifier>Speakers.

Is there any way this configuration could have caused something to go wrong with the amplifier? What precautions could I take in the future, if so?

Thanks!

[YNWaN]

I wouldn't say it is very likely. What is likely is that the electrolytic capacitors in your amp need replacing.

[wee tam]

as above , at that age all caps some resistor work and prob transistor work , the good news is it doesn't cost a fortune as older gear is usually set out better inside than modern slimline stuff so plenty room to work in , my 1969 sansui had all the above work done and in the grand scheme of things inc purchase price and rebuild only stands me around £130 and now will give years of trouble free listening , where are you based ? and someone will point you in the direction of a man that does

[YNWaN]

I wouldn't worry about the resistors (unless they look like they are heat discoloured), or the transistors. Just look for the electrolytic caps (which in gear of that age could be most of them) and replace them.

[Reid Malenfant]

I wouldn't worry about the resistors (unless they look like they are heat discoloured), or the transistors. Just look for the electrolytic caps (which in gear of that age could be most of them) and replace them.
It may be worth changing the output & driver transistors as these will have seen years of heating & cooling, it's only a question of time before they suffer thermal runaway due to the inevitable fracturing of the silicon die from the copper substrate. One day it'll get switched on & it'll die, possibly taking other components out with it.

If it's coming apart then what's an extra £10 or so for another 30 years of service :)

I fully agree with a recap to :)

[maxrob200]

Could be caps or output transistors have popped. Be aware that it may be pouring DC into your speaker voice coils as well if left on and connected. I have fried speakers due to DC

[Lodgesound]

Recently, my 1970s Panasonic SG-165 amplifier started giving me grief. First, I realised audio was only coming out of the right channel - then if I switch round the speaker wires at the back of the unit, the audio comes out of the left speaker, but quietly and distorted.

I don't know what might have caused this, although I recently started using a new configuration of decks with a mixer. The audio was channeled as follows:

Deck(s)>Vestax DJ Mixer>(adapter from mixer's RCA line out to headphone jack)>Aux Input to Amplifier>Speakers.

Is there any way this configuration could have caused something to go wrong with the amplifier? What precautions could I take in the future, if so?

Thanks!




Hi Badger;

Can you confirm how you are connecting your mixer into the amplifier - I'm particularly interested in the "mixer's line out to headphone jack to aux input" bit of your connection description.

Also I assume you have tested the mixer's output to eliminate it from the chain & also tried feeding a source of known good quality to the amplifier.

[theartfulbadger]

Hi Badger;

Can you confirm how you are connecting your mixer into the amplifier - I'm particularly interested in the "mixer's line out to headphone jack to aux input" bit of your connection description.

Also I assume you have tested the mixer's output to eliminate it from the chain & also tried feeding a source of known good quality to the amplifier.

Thanks for all the responses everyone, I really appreciate all the input.

To answer your question, Lodgesound, the mixer outputs audio through a red/black pair of RCA connectors. I got a small adapter to plug into these; one end has male RCA red/black connectors, the other has a single female 3.5mm headphone jack. I had another wire leading from this into the AUX input of my amp.

Is that any clearer?