vintage pioneer, wearing out?? want to fix

[gadgeteer123]

i have a vintage pioneer amplifier from around the early 70's its model number is SA-9100. It has a protect circuit for when it either overheats or gets overloaded, and whenever i let it run for awhile the protect ciruit keeps turning on and off, and sometimes it just stays in protect mode, I want to know how to fix this problem. I have thought about it and i'm thinking that its either that the capacitors are wearing out and can;'t hold a charge for a long time or that the protect switch is just worn out. please help.

 

[dvdchance]

Is the amp getting hot, more then it used to? Are you using different, more difficult to drive speakers? Did anything else change or has it just started going to protect shutdown?

Also check out the forums at audiokarma.com, they have a specific one that has Pioneer gurus there, they helped me with a problem I had with my 70's era SX-880.

 

[gadgeteer123]

the amp is barely even warm, and the speakers are just common sanyo a/v speakers, i think there 100 watt rms, not sure. and the music doesnt have to be cranked for this to happen, even if its at half volume it does it after it has been on for awhile, and also this is weird, i can't figure it out, but it stopped doing the protect problem for a couple days then when i plugged a small fridge which uses 200 watts into the 120v outlet on the back the protect problem came back.

 

[TLS Guy]

i have a vintage pioneer amplifier from around the early 70's its model number is SA-9100. It has a protect circuit for when it either overheats or gets overloaded, and whenever i let it run for awhile the protect ciruit keeps turning on and off, and sometimes it just stays in protect mode, I want to know how to fix this problem. I have thought about it and i'm thinking that its either that the capacitors are wearing out and can;'t hold a charge for a long time or that the protect switch is just worn out. please help.

The most likely explanation is that the output stage has developed significant DC off set. This can come from a variety of causes, failure of zener diodes, the driver transistors or the power transistors. However just about any component in the output stage could cause this. Unless you have a circuit, test gear and preferably a service manual you are unlikely to get far with this problem, without the help of a service tech.

 

[gadgeteer123]

thanks for your response, i know lots about audio, i know how to match it all, i know about quality, and design, but when i comes to the actual circuits on the board i'm a amatuer, i know some but what you just told me i won't be able to figure out, I just love this stereo cuz its built with great quality, and design, again thanks for ur response, I guess its time to invest in another amp.