morning, yes the voltages are accurate and the measurement is from pin 1 of the vertical board and pin 3 of the lm
In the attached image, all points marked in blue are directly connected to pin 1 of the vertical board. Find the ones, on your amp, that are not directly connected (~0 ohms) to pin 1 of the vertical board.
http://www.bcae1.com/temp/IMG_0554b.jpg
http://www.bcae1.com/temp/IMG_0554b.jpg
Perry, the board I have doesn't look anything like what you have posted..
q01 checks out, that is the transistor that is burned.
C06 checks out too, but it is an aluminum capacitor rather than an inductor and comes straight off the tl494 pin 12.
r08 does not check out.
what do you think?
An externally hosted image should be here but it was not working when we last tested it.
http://www.wheelingpics.com/displayimage.php?pid=14310&fullsize=1
An externally hosted image should be here but it was not working when we last tested it.
http://www.wheelingpics.com/displayimage.php?pid=14312&fullsize=1
Last edited:
Perry Babin;1999603]Did any of the IRF640s fail in the class D amp? none were burned, but i have had this amp since 2005 or so, so I figured if I had it open, might as well replace for new now. I replaced everything together except the kb688 and kd718. I forgot to mention that I had replaced the 640s
It doesn't appear that those are causing the amp to go into protect.
Without having a schematic diagram, it's difficult to tell you what to check next. If you disable the protection circuit, that would allow the amp to power up and you could determine if excessive current draw or voltage on one channel was causing it to go into protect.
If you do this, it 'could' cause further damage. To minimize the chance of doing more damage, you would have to have all of the transistors tightly clamped to the heatsink and have either a current limiter or a 10 amp fuse in the B+ line.
If you want to defeat the protection circuit, lifting Q04 should do it.
Without having a schematic diagram, it's difficult to tell you what to check next. If you disable the protection circuit, that would allow the amp to power up and you could determine if excessive current draw or voltage on one channel was causing it to go into protect.
If you do this, it 'could' cause further damage. To minimize the chance of doing more damage, you would have to have all of the transistors tightly clamped to the heatsink and have either a current limiter or a 10 amp fuse in the B+ line.
If you want to defeat the protection circuit, lifting Q04 should do it.
It doesn't appear that those are causing the amp to go into protect.
Without having a schematic diagram, it's difficult to tell you what to check next. If you disable the protection circuit, that would allow the amp to power up and you could determine if excessive current draw or voltage on one channel was causing it to go into protect.
If you do this, it 'could' cause further damage. To minimize the chance of doing more damage, you would have to have all of the transistors tightly clamped to the heatsink and have either a current limiter or a 10 amp fuse in the B+ line.
If you want to defeat the protection circuit, lifting Q04 should do it.
I am game to do it, but my question to you, Is there a good chance we would be able to check voltages and determine, or would we be just as blind going in as we are now without a schematic?
Without having a schematic diagram, it's difficult to tell you what to check next. If you disable the protection circuit, that would allow the amp to power up and you could determine if excessive current draw or voltage on one channel was causing it to go into protect.
If you do this, it 'could' cause further damage. To minimize the chance of doing more damage, you would have to have all of the transistors tightly clamped to the heatsink and have either a current limiter or a 10 amp fuse in the B+ line.
If you want to defeat the protection circuit, lifting Q04 should do it.
I am game to do it, but my question to you, Is there a good chance we would be able to check voltages and determine, or would we be just as blind going in as we are now without a schematic?
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