Hello
I baught this amp with 3 of the 6 ps gets blown. So I replaced all 6 irfz44n along with new 47ohm gate resistors.
When I applied power the same 3 gets blew within 10 seconds. I have done as much research as possible searching the site for info. But haven't had much luck.
After replacing the gets a second time. And powering the amp with a 5 amp fuse as a current limiter.
I was able to check gate voltage. It seems the side that has issue with the fets if I remember correctly was at 5 volts. And the gate voltage for the second set was around 1 volt.
I have connected ground and remote only and checked voltages at the KIA494 but was only able to read Mv. I could post them if helpful
I pulled the npn pnp transistors from the gate with the low voltage. But they seem to be OK
The resistors around the KIA seem to check out ok. But there was one that I checked and the reading was floating and didn't give a solid reading.it was the 104 resistor 3rd to the left of the KIA
I baught this amp with 3 of the 6 ps gets blown. So I replaced all 6 irfz44n along with new 47ohm gate resistors.
When I applied power the same 3 gets blew within 10 seconds. I have done as much research as possible searching the site for info. But haven't had much luck.
After replacing the gets a second time. And powering the amp with a 5 amp fuse as a current limiter.
I was able to check gate voltage. It seems the side that has issue with the fets if I remember correctly was at 5 volts. And the gate voltage for the second set was around 1 volt.
I have connected ground and remote only and checked voltages at the KIA494 but was only able to read Mv. I could post them if helpful
I pulled the npn pnp transistors from the gate with the low voltage. But they seem to be OK
The resistors around the KIA seem to check out ok. But there was one that I checked and the reading was floating and didn't give a solid reading.it was the 104 resistor 3rd to the left of the KIA
I checked as much as I could/know how.
I pulled the board and started double checking everything.
The 2 black capacitors just above the zeners show shorted on my dmm. But not sure how thwy are supposed to operate in the circuit. I haven't pulled the zeners to check them yet.
I pulled the board and started double checking everything.
The 2 black capacitors just above the zeners show shorted on my dmm. But not sure how thwy are supposed to operate in the circuit. I haven't pulled the zeners to check them yet.
Attachments
Go to the following page (you should real ALL of it) but at the very least read the 'Checking Bipolar Transistors' section. The pin configuration for the drivers is EBC.
Basic Amplifier Repair
Basic Amplifier Repair
I have read it. And again recently. Am I able to test them in circuit reliably? Or do I need to remove them to check them?
The small capacitor I said was shorted. I had my negative lead on my DMM connected to the negative terminal of the amp. And when I touched the positive lead to the positive pin on the capacitor. I had continuity.
With the remote/negative trick. I tried it and the green LED came on so I assumed that's what it was for. But unsure
The small capacitor I said was shorted. I had my negative lead on my DMM connected to the negative terminal of the amp. And when I touched the positive lead to the positive pin on the capacitor. I had continuity.
With the remote/negative trick. I tried it and the green LED came on so I assumed that's what it was for. But unsure
Thank you for your help Perry!!
I replaced the fets and gate resistors. With everything in place. The resistors aren't heating up. I've got 4.7 volts at my gates.
1 & 2 channels measured 110mv at speaker terminals
3 & 4 channels measured 10mv at speaker terminals
There are two 20ohm resistors that get pretty hot next to the power supply toroid
I replaced the fets and gate resistors. With everything in place. The resistors aren't heating up. I've got 4.7 volts at my gates.
1 & 2 channels measured 110mv at speaker terminals
3 & 4 channels measured 10mv at speaker terminals
There are two 20ohm resistors that get pretty hot next to the power supply toroid
No outputs transistors failed.
Only 3 of the 6 power fets.
Replaced them with new resistors the first time and right away failed again.
Then started trying to trace gate section. With no luck made my post. Read some more bcae. Pulled all npn & pnp transistors after the KIA chip. Replaced 2 or 3 bad ones.
The gate resistors heated up after replacing the npn and pnp''s
Now I have audio, good voltage (I think) at my gates,
Unsure of the DC at speakers terminals. I do need to double check fet clamps. And bias settings
Only 3 of the 6 power fets.
Replaced them with new resistors the first time and right away failed again.
Then started trying to trace gate section. With no luck made my post. Read some more bcae. Pulled all npn & pnp transistors after the KIA chip. Replaced 2 or 3 bad ones.
The gate resistors heated up after replacing the npn and pnp''s
Now I have audio, good voltage (I think) at my gates,
Unsure of the DC at speakers terminals. I do need to double check fet clamps. And bias settings
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