hello
I received this prestigious amplifier from a Japanese auction.
technics A99 or SU-8099
it is still nicely preserved.
but it has a problem... It turns on but there is no sound...
no click of the relay can be heard... ? what to do
the fuses are all ok
I am attaching pictures.. it was very very very dusty. He had 5 kg of powder. crazy
after cleaning it looks like this.
I received this prestigious amplifier from a Japanese auction.
technics A99 or SU-8099
it is still nicely preserved.
but it has a problem... It turns on but there is no sound...
no click of the relay can be heard... ? what to do
the fuses are all ok
I am attaching pictures.. it was very very very dusty. He had 5 kg of powder. crazy
after cleaning it looks like this.
Attachments
Sorry but the problem is presented very much like "help, my car/computer will not start!". 🙂
The standard advice would be "start measuring all sorts of voltages, starting from power rails, DC on output etc".
What is your experience level in repairing such equipment?
but aren't we on the forum to help each other? here are not only experts but also someone who is learning..
I know a little about electronics.. I know how to measure. I know that this is a very complex amplifier, but it would be nice if I could train it myself. I don't have an oscilloscope.
if anyone has had similar experiences I would be grateful for help.
but I would like step by step..
I know a little about electronics.. I know how to measure. I know that this is a very complex amplifier, but it would be nice if I could train it myself. I don't have an oscilloscope.
if anyone has had similar experiences I would be grateful for help.
but I would like step by step..
Completely true. The first help you can get is advice to search professional help in case the problem exceeds your capabilities.
Which was unfortunately the first impression from your initial post.
But if you say that you understand the amp schematics and can handle the DMM then it is possible to proceed.
So have you got the schematics?
And have you got a DBT (dim bulb tester)?
Well, you can always build one - no spaceflight involved 🙂
But in all honesty - your presented experience seems to be way below the complexity of this amplifier (judging by the schematics).
So do yourself a favor and hand it over to someone who has experience required on this level.
hello after 7 hours of torture checking etc... i came to the problem...
therefore.
the problem is in the board, which I don't know what it's called..
on connector 409 as shown in the picture. right side of the board
the ground gives me 54V which it shouldn't..
connector 409 right plus 402 left lead up to the board where the main transistors are. the left stage connector 402 works properly. the relays turn on and the sound reaches the speakers..
409 ge connector to the right side of the amplifier. (right signal)
therefore. somewhere, 54V is breaking through on pins A and B of connector 409..
I couldn't figure it out.
I suspect the Transistor 2SA772, there are 4 pieces in the faraday cage. and one is behaving strangely.
Look picture.
therefore.
the problem is in the board, which I don't know what it's called..
on connector 409 as shown in the picture. right side of the board
the ground gives me 54V which it shouldn't..
connector 409 right plus 402 left lead up to the board where the main transistors are. the left stage connector 402 works properly. the relays turn on and the sound reaches the speakers..
409 ge connector to the right side of the amplifier. (right signal)
therefore. somewhere, 54V is breaking through on pins A and B of connector 409..
I couldn't figure it out.
I suspect the Transistor 2SA772, there are 4 pieces in the faraday cage. and one is behaving strangely.
Look picture.
