Hi!
As the title says, i dont find these types of FETs here in Europe. Is there a sub for this type?
The amp itself was completely down, transformer noise, excessive current pulling, PS-Fets incl. Gate resistors died and some output FETs.
My question is if there is a substitute which will work in this amp.
I dont know if i should try to fix it when not being able to get spareparts for it.
Thanks in advance !
Best regards!
Andi
As the title says, i dont find these types of FETs here in Europe. Is there a sub for this type?
The amp itself was completely down, transformer noise, excessive current pulling, PS-Fets incl. Gate resistors died and some output FETs.
My question is if there is a substitute which will work in this amp.
I dont know if i should try to fix it when not being able to get spareparts for it.
Thanks in advance !
Best regards!
Andi
Hi!
I just fixed the PS-Supply and the amp isnt pulling much current now. It pulls around 1 amp.
I replaced all PS FETS with IRF3205 and all 4 PS-drivers.
Amp is not in protect and U11 is still out of circuit. I have 105VDC between red and black wires. Power LED is on.
Transformer noise is almost gone, i twisted the transformer and now its almost quiet.
And now my problem comes: i tried to order the IRF6215, but they arent available.
I still have 9540 and 540 . Can i give it a try with these FETs to test the amp?
A hint to substitutes would be great.
All original output FETs are removed from the board.
Thanks again in advance!!
I just fixed the PS-Supply and the amp isnt pulling much current now. It pulls around 1 amp.
I replaced all PS FETS with IRF3205 and all 4 PS-drivers.
Amp is not in protect and U11 is still out of circuit. I have 105VDC between red and black wires. Power LED is on.
Transformer noise is almost gone, i twisted the transformer and now its almost quiet.
And now my problem comes: i tried to order the IRF6215, but they arent available.
I still have 9540 and 540 . Can i give it a try with these FETs to test the amp?
A hint to substitutes would be great.
All original output FETs are removed from the board.
Thanks again in advance!!
Sad to read that 🙁
I also have 9640 and 640N
I will take them just to troubleshoot the audio section with almost no power. So i can be sure everything else is fine.
Thanks!
I also have 9640 and 640N
I will take them just to troubleshoot the audio section with almost no power. So i can be sure everything else is fine.
Thanks!
You can test with no outputs with about 99% certainty.
Desoldering the red and black wires (from the rectifier end) will add a margin of safety.
With no outputs, bridge pins 2 and 6 on U17.
That will give you a 50% duty cycle drive.
If/when you test with outputs, insert a 120v incandescent lamp in series with either the red or black wire to protect the outputs in case there is a problem with the drive.
Desoldering the red and black wires (from the rectifier end) will add a margin of safety.
With no outputs, bridge pins 2 and 6 on U17.
That will give you a 50% duty cycle drive.
If/when you test with outputs, insert a 120v incandescent lamp in series with either the red or black wire to protect the outputs in case there is a problem with the drive.
Hi!
Finally i got the right parts and started working on this amp.
Everything seems fine now but i am unsure because i don really know the BD series and there is one small problem, but mybe its normal?
If i connect a speaker to the outputs i hear a small " pop " at the same moment i touch the remote input with 12V.
I scoped it and there is a negative spike of around 12V on the positive speaker output with scope GND to Amp main GND.
After waiting 2 seconds the output is unmuted.
But it occurs even when the output is unmuted. I shorted C51 it is muting the output as long as its shorted but when shorted the "pop" is very audible.
I also noticed that the spike is exactly the same when i switch the subsonic switch - the same "pop" comes out of the muted output.
Any hints are more than welcome 🙂
Thanks in advance!!
Finally i got the right parts and started working on this amp.
Everything seems fine now but i am unsure because i don really know the BD series and there is one small problem, but mybe its normal?
If i connect a speaker to the outputs i hear a small " pop " at the same moment i touch the remote input with 12V.
I scoped it and there is a negative spike of around 12V on the positive speaker output with scope GND to Amp main GND.
After waiting 2 seconds the output is unmuted.
But it occurs even when the output is unmuted. I shorted C51 it is muting the output as long as its shorted but when shorted the "pop" is very audible.
I also noticed that the spike is exactly the same when i switch the subsonic switch - the same "pop" comes out of the muted output.
Any hints are more than welcome 🙂
Thanks in advance!!
What output did you use to replace the 6215?
What's the DC voltage across the speaker terminals after the mute is released?
What's the DC voltage across the speaker terminals after the mute is released?
I used 6215.
The output voltage is -0.145V across speaker terminals.
Amp idles at 1.8 amps and produces audio and power.
The output voltage is -0.145V across speaker terminals.
Amp idles at 1.8 amps and produces audio and power.
Here is what i got with black wire on main amp ground.
Pin 1: 0.001
Pin 2: -0.003
Pin 3: -0.001
Pin 4: 9.77
Pin 5: -0.001
Pin 6: 0.005
Pin 7: -9.85
Pin 8: -0.003
I also have -0.145V on the output when a load is connected
Pin 1: 0.001
Pin 2: -0.003
Pin 3: -0.001
Pin 4: 9.77
Pin 5: -0.001
Pin 6: 0.005
Pin 7: -9.85
Pin 8: -0.003
I also have -0.145V on the output when a load is connected
Thank you so far , Perry!
I will order one and test it.
I made a mistake in post #8.
The " pop " is audible even when the output is muted.
It pops together when Power and Protect LED start to glow at the same moment the remote jack gets contact with 12V.
Its not really a problem for me because the amp is working and this amp is a learning-project.
But if it can get fixed i will try to get this done. I dont have or ever had another BD so i thought it is normal.
This amp also has strange behavior, the transformer sometimes starts to make a "whining" noise.
I will order one and test it.
I made a mistake in post #8.
The " pop " is audible even when the output is muted.
It pops together when Power and Protect LED start to glow at the same moment the remote jack gets contact with 12V.
Its not really a problem for me because the amp is working and this amp is a learning-project.
But if it can get fixed i will try to get this done. I dont have or ever had another BD so i thought it is normal.
This amp also has strange behavior, the transformer sometimes starts to make a "whining" noise.
There should be no output drive until the end of the mute delay.
Is there any rail-rail oscillation on the output transistors before the initial mute delay ends?
Is there any rail-rail oscillation on the output transistors before the initial mute delay ends?