Pioneer sa7100 pioneer output help

[JohnKuz1]

Hi.
I'm a new member.
Sorry for a redundant post, but I've tried to read the the forums and I'm not quite understanding how to proceed and what my options are in going forward.

I powered on amp for about 3minutes. Just acquired it. Played fine but then started to click into protection mode. It clicked back a few times and now it won't get out of protection mode. Pioneer wasn't hot and there was no popping or anything loud from speakers. Preamp is working
My questions are:
1) If indeed it's an output power issue what do I need to look for and how to identify the problem.
If someone can give me just a quick short list of the steps for diagnosis (in layman's terms),and.
2) I'd also like to learn what was the probable cause and if there are any simple measures to rule out other than output power.
Any information would be helpful.
I appreciate it.

 

[mbz]

Probably best to move to the Pioneer forum, the guru's there will look after you. Hit the "Report" link at bottom of post and request moderator to move...

Two basic scenarios. The amp is failing intermittently in either one or both channels or in the power supply or there is a failure in the protection circuit. A good starting point is to measure the dc voltages at the power amp outputs of each channel. Will get you some test points...

 

[mbz]

Carefully measure the DC voltage between power amp pin 17(RED meter probe) and GND/Any black speaker connector.
Repeat for pin 2 and GND. Ideally both should be 0mV but upto 100mV is tolerable.

 

[moodydan]

If you have not yet started a thread in the Pioneer subforum as previously suggested, that will be your best bet. More than likely, it's troublesome transistors that are known problems. The 7100/8100/9100 is my favorite line of the Pioneers, definitely worth getting up and running,

 

[markthefixer]

Hi.
I'm a new member.
Sorry for a redundant post, but I've tried to read the the forums and I'm not quite understanding how to proceed and what my options are in going forward.

I powered on amp for about 3minutes. Just acquired it. Played fine but then started to click into protection mode. It clicked back a few times and now it won't get out of protection mode. Pioneer wasn't hot and there was no popping or anything loud from speakers. Preamp is working
My questions are:
1) If indeed it's an output power issue what do I need to look for and how to identify the problem.
If someone can give me just a quick short list of the steps for diagnosis (in layman's terms),and.
2) I'd also like to learn what was the probable cause and if there are any simple measures to rule out other than output power.
Any information would be helpful.
I appreciate it.

Sorry to say this, but it isn't a short list of steps for this old gent. It's chock full of "shoot on sight" transistors,
any of which could be the one that's CURRENTLY acting up.
Then to add insult to injury, Pioneer used the sky blue Sanyo electrolytic caps, which are guaranteed failures to short circuits.
I have a SA-9100 waiting in the wings, they share a lot of parts, and I don't DARE power it up with those parts still inside.

Plus these older models are subject to hard to understand service manuals.

Other than temporary parts shortages the parts to be replaced are inexpensive and common, easily acquired
(there are sources that stockpiled parts a while back) with whole parts kits.

But you need to know or learn how to locate and install specific parts (transistors, e-caps and so forth)

For example, the power amp has 7 transistors per channel INCLUDING the outputs.
If you are lucky, the really bad 2sc1451 has NOT cut lose (yet) and pulled off a suicide strike.
Replace the 2sa726's (two of them) and the 2sc1451, rescuing your more expensive outputs and drivers.

first, we get the power supply reliable,
then get the protect circuit reliable.
then the power amp fixed up.
Then finally all the rest of the sound handling circuits.

Once these updates are done, you will have something you can put up on a shelf and enjoy for years.

possible problems?
tired relay driver transistor
non-constant power supply.
intermittent fault in protect - causing false triggering
JUSTIFIED protect triggering, maybe a troublemaker is warming up to take out the amp
intermittent in the power amp causing justified triggering.
the list can go on and on, and sounds really discouraging.

However the stuff that crosses our benches comes out much the better for it.
We've had decades to learn where to "cut them off at the pass".

You learn to desolder / solder, locate components inside and install e-caps, transistors and diodes you will be in good shape
and there will be plenty of hand holding available if needed.
You will be someone's eyes, ears and hands.
They will supply the specialized knowledge.

One important one: There are small components mounted with a screw on the heat sinks (black w fins) yet wired into a DIFFERENT board, thermal diodes. Those wires are fragile, they love to break.


so don't bend the last 1/2 inch of wire from the component's case.

 

[JohnKuz1]

Sorry to say this, but it isn't a short list of steps for this old gent. It's chock full of "shoot on sight" transistors,
any of which could be the one that's CURRENTLY acting up.
Then to add insult to injury, Pioneer used the sky blue Sanyo electrolytic caps, which are guaranteed failures to short circuits.
I have a SA-9100 waiting in the wings, they share a lot of parts, and I don't DARE power it up with those parts still inside.

Plus these older models are subject to hard to understand service manuals.

Other than temporary parts shortages the parts to be replaced are inexpensive and common, easily acquired
(there are sources that stockpiled parts a while back) with whole parts kits.

But you need to know or learn how to locate and install specific parts (transistors, e-caps and so forth)

For example, the power amp has 7 transistors per channel INCLUDING the outputs.
If you are lucky, the really bad 2sc1451 has NOT cut lose (yet) and pulled off a suicide strike.
Replace the 2sa726's (two of them) and the 2sc1451, rescuing your more expensive outputs and drivers.

first, we get the power supply reliable,
then get the protect circuit reliable.
then the power amp fixed up.
Then finally all the rest of the sound handling circuits.

Once these updates are done, you will have something you can put up on a shelf and enjoy for years.

possible problems?
tired relay driver transistor
non-constant power supply.
intermittent fault in protect - causing false triggering
JUSTIFIED protect triggering, maybe a troublemaker is warming up to take out the amp
intermittent in the power amp causing justified triggering.
the list can go on and on, and sounds really discouraging.

However the stuff that crosses our benches comes out much the better for it.
We've had decades to learn where to "cut them off at the pass".

You learn to desolder / solder, locate components inside and install e-caps, transistors and diodes you will be in good shape
and there will be plenty of hand holding available if needed.
You will be someone's eyes, ears and hands.
They will supply the specialized knowledge.

One important one: There are small components mounted with a screw on the heat sinks (black w fins) yet wired into a DIFFERENT board, thermal diodes. Those wires are fragile, they love to break.


so don't bend the last 1/2 inch of wire from the component's case.

View attachment 2617601

Wow!

Man, I can't thank you enough, as well as gratitude for the 2 posts prior from Moody Dan and mbz.
It took a lot of time and thought for providing such an extensive and succinct reply. You rock!

I guess my options would be:

1) take it to a technician to have repaired.
But here in Louisville KY there is only one vintage gear shop and they are good but expensive. And, usually the turn around time is a month or longer.

2) sell on eBay for parts or

3) pass it along to someone who will undertake the journey and process by themselves.

4) start the daunting undertaking myself. My knowledge is limited and would require a commitment and a lot of patience.

I wish I knew someone in Louisville that I could learn from who would have the time to walk me through the process of repair.

My lack of funds and the desire to have it working may ultimately force my hand to #4.


Thanks again.

Any other comments or suggestions are welcome.