If you power up the amp, what is the DC voltage across the speaker terminals?
Did you replace the 4 driver transistors?
Did you replace the 4 driver transistors?
Without any speaker is around 1.5v but oscilating.
I did, it did not do anything. I also tested the old ones with the ESR meter and they look fine.
I did, it did not do anything. I also tested the old ones with the ESR meter and they look fine.
I had 1.5v with the old driver transistors as I've used them to be certain everything is as it should since I could only find replacements. I swapped them with the new ones now. I still have around 0.3v across terminal which goes up slowly. I can hear a light background noise in the speaker now.
Also, some of the output FETs are randomly getting hot in a minute.
The high pitch sound which I believe to be the transformer, changes frequency everytime I do anything like probing a part or just touching a FET to check for temp.
Also, some of the output FETs are randomly getting hot in a minute.
The high pitch sound which I believe to be the transformer, changes frequency everytime I do anything like probing a part or just touching a FET to check for temp.
Without a scope, it may be difficult to troubleshoot. Even with a scope, it may be difficult for me to help since I'm not very familiar with this IC.
Drive waves look allright on the FET's. Just no input. And not sure about the heating up part.
I'm checking again the voltages on the IC and some are not allright compared to twilliar's. I have a 5v on pin 5 where he has 0. I'm checking that now.
Still not giving up on it as it's the last one, all other amps I had to repair are working now.
I did learn a lot compared to since I've started all this so I can only thank you for all the help. It's probably some annoying small thing that I can't find 🙂
I'm checking again the voltages on the IC and some are not allright compared to twilliar's. I have a 5v on pin 5 where he has 0. I'm checking that now.
Still not giving up on it as it's the last one, all other amps I had to repair are working now.
I did learn a lot compared to since I've started all this so I can only thank you for all the help. It's probably some annoying small thing that I can't find 🙂
I'm now pretty sure that the massive output inductor could be actually faulty as it seems that's the source of the high pitch sound I could hear until now. It just transformed into a proper static sound, almost as tunning into a radio station.
So, do you have a scope?
List all of the equipment and power supplies in your sig file. I can't possibly remember what people have.
From the datasheet, 5v on pin 5 looks right.
List all of the equipment and power supplies in your sig file. I can't possibly remember what people have.
From the datasheet, 5v on pin 5 looks right.
I updated the signature.
So it wasn't the inductor after all, though that sound it does seem to be coming from that direction.
Now, when that sound amplitude changes, on the speaker terminal besides the DC voltage, which after reseating the 2092 properly again, has dropped to 0.3v but going up slowly when speaker is attached, there is a bunch of AC voltage spikes. It oscilates randomly from 0 to even 17v.
On the scope, even if the drive wave on the FETs looks fine, it does have some, I can only describe it as a leak, a line that goes down from the point where the wave hits the bottom part and one that goes up from where it hits the top part, at random times. I did check this straight on the IC as well so I can rule out the driver transistors.
Taking the fact that the voltage on the gate of the high side FETs and in other places of the IC is oscilating continuosly, even though in small amounts, makes me think that the voltages are not being fed correctly to the IC still.
So it wasn't the inductor after all, though that sound it does seem to be coming from that direction.
Now, when that sound amplitude changes, on the speaker terminal besides the DC voltage, which after reseating the 2092 properly again, has dropped to 0.3v but going up slowly when speaker is attached, there is a bunch of AC voltage spikes. It oscilates randomly from 0 to even 17v.
On the scope, even if the drive wave on the FETs looks fine, it does have some, I can only describe it as a leak, a line that goes down from the point where the wave hits the bottom part and one that goes up from where it hits the top part, at random times. I did check this straight on the IC as well so I can rule out the driver transistors.
Taking the fact that the voltage on the gate of the high side FETs and in other places of the IC is oscilating continuosly, even though in small amounts, makes me think that the voltages are not being fed correctly to the IC still.
Well, I probably killed something again last night, as I have a bunch of weird voltages on chip, between legs 1-6. The ones that had 0 now have 4.36 or -4.12
Chip no longer does nothing again but readings are in the range of Mega Ohms so it doesn't seem to be gone. Probably a resistor or transistor in it's path. I'll see if I can find anything obvious and if not, I'll probably write it off. It's time consuming now and no results. I don't usually give up on anything, reason why I sometimes spend more on repair than what it's worth, but this could be a first....
Chip no longer does nothing again but readings are in the range of Mega Ohms so it doesn't seem to be gone. Probably a resistor or transistor in it's path. I'll see if I can find anything obvious and if not, I'll probably write it off. It's time consuming now and no results. I don't usually give up on anything, reason why I sometimes spend more on repair than what it's worth, but this could be a first....
With the air, but it was working fine afterwords. I think it has died when I was checking why does it have that 5v on the pin where it was 0 before so I removed the capacitor that goes to the pin so I can check if the voltage is generated by the IC or externally.