Hi. I am repairing a DD Z2, which exploits the output transistors. only the 6 transistors left part near rectifier diode.
I have checked the output drive board and all good, replaced IR21844S as a precaution, but when connecting a speaker to the output, it explodes again the 6 transistors that I said previously.
What can happen?
Greetings.
I have checked the output drive board and all good, replaced IR21844S as a precaution, but when connecting a speaker to the output, it explodes again the 6 transistors that I said previously.
What can happen?
Greetings.
Are all of the 2.2 ohm resistors within tolerance? R272A(?) looks like it got really hot.
Have you checked all of the small 47uH inductors. Some aare for the protection circuit and if one is open, the protection circuit may not function (and protect the FETs).
After the last FET failure, have you replaced all of the driver ICs?
After replacing them, did you compare the readings of all of them to determine if one was damaged when installing them?
You can pull the rectifiers and drive a strong signal into the amp (50-100Hz) and see if you get a good clean square wave at every FET gate leg.
Have you checked all of the small 47uH inductors. Some aare for the protection circuit and if one is open, the protection circuit may not function (and protect the FETs).
After the last FET failure, have you replaced all of the driver ICs?
After replacing them, did you compare the readings of all of them to determine if one was damaged when installing them?
You can pull the rectifiers and drive a strong signal into the amp (50-100Hz) and see if you get a good clean square wave at every FET gate leg.
Hello
I have had problems with the DD Z2 again. The output transistors have exploded again.
All these components are revised and correct:
R271-271A OK
R272-272A OK
R201, R186, R187 OK
Inductors OK (none open)
DRIVE BOARD:
4 IRS21844S new
TL072 and LM211 new
R44 and R36 OK
D5, D1, D6, D3 OK
The voltages 12v, +15, -15, +5, -5 are present.
Any idea what is happening?
Greetings.
I have had problems with the DD Z2 again. The output transistors have exploded again.
All these components are revised and correct:
R271-271A OK
R272-272A OK
R201, R186, R187 OK
Inductors OK (none open)
DRIVE BOARD:
4 IRS21844S new
TL072 and LM211 new
R44 and R36 OK
D5, D1, D6, D3 OK
The voltages 12v, +15, -15, +5, -5 are present.
Any idea what is happening?
Greetings.
failed a test in the bank. it ran out of audio output. I turned off again, I heard a loud noise to static electricity and some output transistors exploded.
the components described above were checked before it failed again. Now I have to check all of them again. it is likely that IRS21844 from the failed side is in poor condition.
Do you know any way to check the output pulses of IRS21844 without having transistors connected to the board?
the components described above were checked before it failed again. Now I have to check all of them again. it is likely that IRS21844 from the failed side is in poor condition.
Do you know any way to check the output pulses of IRS21844 without having transistors connected to the board?
Remove the rectifiers and install the output transistors. Without rail voltage, they can't be easily damaged. Replace all known defective components (including any failed 21844s) and drive a sine wave of 50-100Hz into the amp. Check the signals on the gates of the output FETs. Having the FETs in the circuit loads the drive circuit and helps show any deficiencies.
You'll have to provide the high-side of the IC with a supply (9v battery works).
You'll have to provide the high-side of the IC with a supply (9v battery works).
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