Hello.
Integrated amplifier TECHNICS SU 3500.
Some problems.
Preamp white noise on all sources volume on zero.
Power amplifier protect mode.
All transistors (power transistors and driver )
dessoldered tested and are ok.
Two or one power board Amplifier connect...... protect mode.
Not connected 2 or one power board Amplifier works fine(preamp).
But white noise....
The sound is very good (on preamp),but with white noise.
SM
https://elektrotanya.com/technics_su-3500_service_manual.pdf/download.html
Integrated amplifier TECHNICS SU 3500.
Some problems.
Preamp white noise on all sources volume on zero.
Power amplifier protect mode.
All transistors (power transistors and driver )
dessoldered tested and are ok.
Two or one power board Amplifier connect...... protect mode.
Not connected 2 or one power board Amplifier works fine(preamp).
But white noise....
The sound is very good (on preamp),but with white noise.
SM
https://elektrotanya.com/technics_su-3500_service_manual.pdf/download.html
i have had problems with solder on the main board and all small value capacitors needing replacing there and on the tone boards
I tested all parts on two power board.
No bad parts,all ok.
But if I install one or two power board on Amplifier ...... protect mode.
No bad parts,all ok.
But if I install one or two power board on Amplifier ...... protect mode.
protection disconnects supply to main ht
if its making a noise it is likely to be transistor or dry joints
if its making a noise it is likely to be transistor or dry joints
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But tell me please how does it works protect on this Amplifier?
where does the current come from that turns on the protect relay. ?
where does the current come from that turns on the protect relay. ?
The protection circuit consists of TR603 (2SC1318), TR602 (2SC1318) and TR601 (2SA684) which drives the relay coil.
The sense is picked up from the amplifier outputs, via R608 and R609 (10K each).
The protection circuit is powered up by D511 and C530; the power comes from half of the secondary coil - referenced to the ground.
Good luck.
If I connect 2 power boards....4.6V DC on R608 & R609.
All transistors of power board desoldered and tested with part tester....all ok.
Capacitors on power boards ...ok
Soldering joints ....ok....
+-40v ....ok
+-37v...ok
If i take away 2 fuses F2 & F3 no protect mode.
All transistors of power board desoldered and tested with part tester....all ok.
Capacitors on power boards ...ok
Soldering joints ....ok....
+-40v ....ok
+-37v...ok
If i take away 2 fuses F2 & F3 no protect mode.