Pioneer A-60 Rebuild-Restore

[nadude98]

Did you change out that transistor?

Ordered it as well as a couple of outputs. While I was at work my wife got it to work by messing with the tape monitor switches. What can go bad that would cause a channel to stop working yet come back by doing that? By killing the input for a sec. A cap? Hmmm

 

[laatsch55]

Dirty switches....

 

[Fishoz]

De-Oxit to the rescue!!

 

[laatsch55]

Yeppers....

 

[orange]

I would trace back to the bigass cap that's bound to be involved and look underneath to see if you have a burnt spot, bad joints or a damaged trace in the vicinity.

 

[nadude98]

Got parts in, replaced the two outputs in the middle of left channel that had shown signs of getting hot and also the two "pre-drivers?" I had already thoroughly deoxited it, rechecked everything.. looked for bad solder traces etc. Fired it up and so far it is working like a charm... and sounds golden again!

 

[laatsch55]

Gone past the golden hour??

 

[nadude98]

Gone past the golden hour??

So far, so good! Just put on the cover and back in the entertainment center.. see how it does when it gets a little toastier.

Well, didn't last long after I put the cover on.. there is more going on. I can tell it's improved but there is still something failing with heat..! Think I'll replace the other two outputs.. and ?

 

[nadude98]

Time to put it to rest for now... Gotta prep for the trip to Phoenix!

 

[nadude98]

I would trace back to the bigass cap that's bound to be involved and look underneath to see if you have a burnt spot, bad joints or a damaged trace in the vicinity.

I couldn't find anything..

 

[orange]

I remember those things...in the good old daze if something went wrong with Windows (say 98 or 2000) if you ignored it for a while it would get lonely and feel guilty or something and suddenly work again.

Keep your eyes and ears on it for awhile though.

Just remember to feed it lots of odd, very distorted but righteous waveforms from multiple sources, skip aspirin unless you have a headache and call us in the morning.

 

[nadude98]

I remember those things...in the good old daze if something went wrong with Windows (say 98 or 2000) if you ignored it for a while it would get lonely and feel guilty or something and suddenly work again.

Keep your eyes and ears on it for awhile though.

Just remember to feed it lots of odd, very distorted but righteous waveforms from multiple sources, skip aspirin unless you have a headache and call us in the morning.

But the lime in the coconut and call us in the morning.....say ya ya!

 

[nadude98]

Okay, this thing still wants to act up occasionally on the left channel... hitting the tape monitor in and out can bring the channel back... I have deoxited and faderlubed all appropriate controls...... at a loss here! Last thing I did was change the 0.33ohm 5watt emitter resistors on the left channel where one leg was measuring about 1.5 ohm. It helped to a degree but not totally!

 

[laatsch55]

Good tune....

 

[laatsch55]

On really bad switches and pots I've had to de-oxit up to 3 times....

 

[nadude98]

Good tune....

I love some Nilsson Schmilsson! Great album!!!!

 

[laatsch55]

Me too, classic stuff....

 

[nadude98]

Equalizer Assy advice

After some research I thought I would try to make an improvement to the A-60 Equalizer board. I replaced Q807,808 NJM4558DXC's with OPA2134's and Q805,806 2SA970's with KSA992's. It seems to have made the sound seem...

brighter, almost sibilant, not quite harsh but? Would the A992's affect anything? After modding the Carver C4000 with the OPA's I was hoping for a similar result. Bad idea? Better choice of op-amp or restore to original?



well hell, that didn't work too well....

 

[laatsch55]

That's what happens when you change more than one thing at a time...

 

[Gepetto]

After some research I thought I would try to make an improvement to the A-60 Equalizer board. I replaced Q807,808 NJM4558DXC's with OPA2134's and Q805,806 2SA970's with KSA992's. It seems to have made the sound seem...

brighter, almost sibilant, not quite harsh but? Would the A992's affect anything? After modding the Carver C4000 with the OPA's I was hoping for a similar result. Bad idea? Better choice of op-amp or restore to original?

View attachment 24590

well hell, that didn't work too well....

Cannot read the schematic (too small) so it is hard to recommend much Jim.