Hi,
First of all I have to say I am a reaaaal beginner at fixing electronics and especially amplifiers.
I recently got myself a Pioneer amplifier which is locked in protection mode.
I checked all of the big Mosfets and they seemed good.
I found 1 thing that was weird for me. I found 2 diodes which seemed to be shorted -MBRF20200CT and MBRF20200CTR. I pulled them off the board, but when tested off board they were fine. So a question popped my mind. Are these point supposed to be shorted together?
I found out these points end up in the transormer:
Are all of these supposed to be shorted together?
What else should I look for?
The amp shows blue light like a millisecond and goes to protect right away.
First of all I have to say I am a reaaaal beginner at fixing electronics and especially amplifiers.
I recently got myself a Pioneer amplifier which is locked in protection mode.
I checked all of the big Mosfets and they seemed good.
I found 1 thing that was weird for me. I found 2 diodes which seemed to be shorted -MBRF20200CT and MBRF20200CTR. I pulled them off the board, but when tested off board they were fine. So a question popped my mind. Are these point supposed to be shorted together?
I found out these points end up in the transormer:
Are all of these supposed to be shorted together?
What else should I look for?
The amp shows blue light like a millisecond and goes to protect right away.
Your meter is simply reading the resistance of the secondary windings which is essentially 0 ohms. This is normal.
Photo of the entire board?
What are the output driver ICs?
Photo of the entire board?
What are the output driver ICs?
Attached some pics.
Not a good quality camera, sorry. I believe this IC (on the chip is written: IRS209m) is playing tricks.
Surrounding of it is a bit discoloured and there was corrosion beneath the chip. Gave it a good clean with IPA. The pins do not look good. I think this chip has to come off.
I know this is just stupid to diagnose amps over internet but I am working blind here to be honest. No oscilloscope and no practical knowladge to use it 😀
1 thing I noticed is that these Mosfets (red circles) got hot when the amp was powered:
These were C2026 and A1046, but tested ok off the board. I think there is a short somewhere which drives those mosfets hot. Could it be the IC?
Maybe some 1 has service manual for that amp? Would be good to see some schematics.
Not a good quality camera, sorry. I believe this IC (on the chip is written: IRS209m) is playing tricks.
Surrounding of it is a bit discoloured and there was corrosion beneath the chip. Gave it a good clean with IPA. The pins do not look good. I think this chip has to come off.
I know this is just stupid to diagnose amps over internet but I am working blind here to be honest. No oscilloscope and no practical knowladge to use it 😀
1 thing I noticed is that these Mosfets (red circles) got hot when the amp was powered:
These were C2026 and A1046, but tested ok off the board. I think there is a short somewhere which drives those mosfets hot. Could it be the IC?
Maybe some 1 has service manual for that amp? Would be good to see some schematics.
Attachments
Last edited:
https://www.bcae1.com/repairbasicsforbcae1/repairbasics.htm
^^^ Read that page.
Your amp looks like the 9705 without the sub channel.
The parts that are getting hor are not FETs. They're bipolar transistors being used as voltage regulators and it's normal for voltage regulators to run hot. Don't let them get too hot. If they do and fail, they could cause a lot of damage.
The IC is likely a 2093.
The FETs driven by the 2093 look like the one in the photo.
^^^ Read that page.
Your amp looks like the 9705 without the sub channel.
The parts that are getting hor are not FETs. They're bipolar transistors being used as voltage regulators and it's normal for voltage regulators to run hot. Don't let them get too hot. If they do and fail, they could cause a lot of damage.
The IC is likely a 2093.
The FETs driven by the 2093 look like the one in the photo.
