I have a strange problem with this set.
Everything is good but after some time whatever is play, cd or radio, not the same every time, this go to standby.
I had a look inside the tuner and power amplifier.
In the class D amplifier board fet aren't well pushed against heatsink but after some rework the problem not solved.
I had measure for d.c present at the output but everything is good.
Any help?
Everything is good but after some time whatever is play, cd or radio, not the same every time, this go to standby.
I had a look inside the tuner and power amplifier.
In the class D amplifier board fet aren't well pushed against heatsink but after some rework the problem not solved.
I had measure for d.c present at the output but everything is good.
Any help?
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Thimios, I would think it is something coming from the control circuit. The circuit is surely using a standby circuit, I thing the problem is there.
Yes but all errors,like d.c presence or overheat problems will act the stand by.
That's why i looked inside the power amplifier.
I had examine the radio also (microprocessor is inside the radio)but i can't see dry solders or something.
That's why i looked inside the power amplifier.
I had examine the radio also (microprocessor is inside the radio)but i can't see dry solders or something.
SE HD60 amplifier makes loud "bzzz" then goes to standby
I have a similar problem: Regardless of what we are listening to, after a while, the amp makes a loud BUZZZZ that lasts maybe 1 second and then goes into standby (protection I guess).
I have already opened it and visually inspected the amp board. There's a very nice service manual with schematics available from Technics here
My question is: What could be the root cause for this? I was wondering if one of the FETs maybe has a thermal problem? But why would it then make "BZZZZ"? I resoldered the FET and flipflop connections but the problem still persists from time to time.
I also suspected it could be something as stupid as the connections to the speakers. But then why would that result in the "BZZZ". It almost feels like the switching circuit that alternates between the FETs would resonate at a completely wrong frequency, way too low. Could that be?
Any electronics engineers here familiar with these class B FET amplifiers?
My studies at University are too long ago and I simply don't remember right how these are designed...
I have a similar problem: Regardless of what we are listening to, after a while, the amp makes a loud BUZZZZ that lasts maybe 1 second and then goes into standby (protection I guess).
I have already opened it and visually inspected the amp board. There's a very nice service manual with schematics available from Technics here
My question is: What could be the root cause for this? I was wondering if one of the FETs maybe has a thermal problem? But why would it then make "BZZZZ"? I resoldered the FET and flipflop connections but the problem still persists from time to time.
I also suspected it could be something as stupid as the connections to the speakers. But then why would that result in the "BZZZ". It almost feels like the switching circuit that alternates between the FETs would resonate at a completely wrong frequency, way too low. Could that be?
Any electronics engineers here familiar with these class B FET amplifiers?
My studies at University are too long ago and I simply don't remember right how these are designed...
Guess, just guessing....
the power on/off button switch....
as time goes by, humility or other reason dirt was formed and later became conductive.
this can course shorts between pads on the board.....I experienced this...
the button switch inside could be defective, deformed, loosen inside, dirt inside...
try clean along the button path with 3 in 1 spray.
or cut off the power on/off circuitry to test.
the power on/off button switch....
as time goes by, humility or other reason dirt was formed and later became conductive.
this can course shorts between pads on the board.....I experienced this...
the button switch inside could be defective, deformed, loosen inside, dirt inside...
try clean along the button path with 3 in 1 spray.
or cut off the power on/off circuitry to test.
Thanks, that's an interesting track I need to investigate indeed. It doesn't feel like it could be the power button as pressing on the button to switch it off would not generate that loud buzz (and the button works quite reliably). But maybe that button controls some secondary circuit. I'm more suspecting the FETs though. But have not enough experience in amplifier design.