There are no output fets installed. The amp came in with no fets. Do you perhaps also know which output fets should be used in this amp?
The measurements taken from last posts are taken with the diode D402 still out of the circuit.
I will re-install D402 and measure, remove U401 and take some new measurements to try to find the causing for the DC offset.
The measurements taken from last posts are taken with the diode D402 still out of the circuit.
I will re-install D402 and measure, remove U401 and take some new measurements to try to find the causing for the DC offset.
Output fet switching seems to work, I soldered one fet per bank (2 banks).
Idle current draw is pretty high, about 3.8A at 12.6v. U401 heats up pretty much, output inductors get quite hot.
The fet switching seems very clean for one fet per bank.
Unfortunately there is a perfect triangle wave on the + terminal (photo attached)
Other photo attached is the output fet switching.
Idle current draw is pretty high, about 3.8A at 12.6v. U401 heats up pretty much, output inductors get quite hot.
The fet switching seems very clean for one fet per bank.
Unfortunately there is a perfect triangle wave on the + terminal (photo attached)
Other photo attached is the output fet switching.
Attachments
I never measured the temperature but I know the inductors will get too hot to hold continuously.
The op-amp is very nearly driving a 100 ohm load at full rail to rail (±15v) continuously. Not a great design but it's generally reliable.
I'm sorry that I missed where you stated that all of the outputs were out of the circuit. That wasted some time.
The op-amp is very nearly driving a 100 ohm load at full rail to rail (±15v) continuously. Not a great design but it's generally reliable.
I'm sorry that I missed where you stated that all of the outputs were out of the circuit. That wasted some time.
Please, don't apologize 
I think you are the last person on this forum who ever needs to give an apology. I'm very very grateful for your big effort to help all of us techs.
Ahhaa, that's a very stressfull load. If I would be the engineer I would clamp it to a heatsink or cooling fan. I will place an extra cooling fan over the drive circuit to make sure it's more reliable in the future.
I plugged in the filter board (I tested with jumper wires before). I get no sound out of it. Also the light does not work on the filter card. I do measure +-15v and +-12v on the jumper wires.
Also, LED400 and the service LED is still on. Current pull with all fets in is 4a at 12.6v
Strange, because the output fets barely / dont heat up.
I think you are the last person on this forum who ever needs to give an apology. I'm very very grateful for your big effort to help all of us techs.
Ahhaa, that's a very stressfull load. If I would be the engineer I would clamp it to a heatsink or cooling fan. I will place an extra cooling fan over the drive circuit to make sure it's more reliable in the future.
I plugged in the filter board (I tested with jumper wires before). I get no sound out of it. Also the light does not work on the filter card. I do measure +-15v and +-12v on the jumper wires.
Also, LED400 and the service LED is still on. Current pull with all fets in is 4a at 12.6v
Strange, because the output fets barely / dont heat up.
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