Hi guys.
Today I received a Technics SE-9600 amp from a friend. When turning off the unit, there is a humm present for a while, and a squishing noise that rises in pitch until it's gone. It drives my friend crazy...
Could that be an issue with the relay? Or maybe the ginormous 10.000uF / 80V electrolytic caps? I replaced all caps except those in the past.
Today I received a Technics SE-9600 amp from a friend. When turning off the unit, there is a humm present for a while, and a squishing noise that rises in pitch until it's gone. It drives my friend crazy...
Could that be an issue with the relay? Or maybe the ginormous 10.000uF / 80V electrolytic caps? I replaced all caps except those in the past.
This amplifier doesn't use a normal speaker relay, the relay in this unit cuts the ACV to the bridge rectifier. What you hear is the + and - supplies collapsing, probably at different rates. Has it always done this or something new?
Craig
Craig
I'm not sure, I never paid much attention to it. Also, this amp does not belong to me, I only had it twice, one time to repair one driver board, the other one for a recap job, except the big ones on the PSU.
But I guess it must be new, otherwise my friend wouldn't have brought it to me.
But I guess it must be new, otherwise my friend wouldn't have brought it to me.
Doesn't it also switch to relay pin 6, which feeds D509 in the regulated power supply? After that I lose it.
Actually yes, kind of. When the relay cuts power to the rectifiers on the PSU, It switches this power to D509. But at the same time it cuts power to the other half of the rectifiers, so there should not be much going on.
The normal operating state of the relay is de-energized. When a problem is detected the relay energizes and disconnects power to the power supply so now there is no voltage to keep the relay energized. This is where Pin 6 of the relay comes into play, it provides ACV to rectifier D509 and C506, this small supply keeps the relay energized and in protect mode.