Want to share:
Have downloaded the schematics from this forum to help repair the amplifier of a friend.
Turned out that Sony decided to route the earth through the chassis, even the earth between the various supplies.
When one takes the main board out of the chassis and switches the amp on, there are up to 20 volts difference between the eart (and hence reference) of the pre-amps and the main amps.
Luckily the amp goes into protection but from a design point of view it is not nice to rely on screws and aluminum face plates to conduct up to 0.2 amps of current from one supply to another.
What I did is solder wires to every eart point and connected them on the main board to make it stand alone and not rely on conducting current through the chassis anymore.
Bad design, simple repair but took some digging in the schematics to find out what exactly was going on!
Friends Sony STR DH130 goes into protection mode soon after turning on. It works for a second then can hear loud pops from speakers.
I've tried the suggested methods to fix but nothing works. Correct impedance speakers. Speakers wired correct. Good ventilation.
I've tested the output transistors in circuit and I don't see anything unusual. I may pull them to test but will wait for advice here. I also measure
about 57 volts on the emitter resistors. Seems high to me. Anyone?
Szép jó napot mindenkinek.
Van nállam egy Sony HCD C50 hifi ami nem indul, a Pause led power gomb megnyomásákor 3 villan.
12V,+/-7 V ,5V megvan a Power off vonalon ott is 5V van.Ez a villogás hibaüzenetre utal,találkozott valaki ilyennel?
Üdv András
Sziasztok!
Az erősítő problémája a következő:
bekapcsolás után a hangszórók működése szinte véletlenszerű.
Hol sub+front hol front+ rear stb...
A kolléga aki rámsózta hangprocira gyanakszik,de ezt állítólag a gyártó
csak szakszervíznek adja ki.Szerintem más hjiba lehet..
Ötlet?
előre is kösz
Sanci7212