Tom,
I just got done working on one of these a month ago..
I see you posted on someone else's thread ..
Here is a new thread so we can start fresh ..
What is the amp doing or not doing maybe I can offer you some advice ..
I just got done working on one of these a month ago..
I see you posted on someone else's thread ..
Here is a new thread so we can start fresh ..
What is the amp doing or not doing maybe I can offer you some advice ..
Thanks SMerlington,
I have done quite abit of troubleshooting and I need another brain. This is a Sampson 8K amp. It uses the 3S driver PCB (4 irs21844s), and (32) irfp460LC outputs.
When I got it, (4) of the 470's exploded, in all different parts of the output section.
So I did the usual, replaced all 4 drivers IC's and the 2D driver transistors. I installed 1 of the 4 irf460's in each circuit (instead of 4) for a total of 8, and turned on the amp. And it worked, power up and relays click.
I proceeded to install all the outputs, and discovered as soon as I powered up, it went into protection in about 2-3 secs. I was a bit confused, so I ohm'ed all the outputs, good. checked all the gates resistors, they are good. The (4) 2.2ohm, 47uh inductors, measure the LC inductors values (80uh) good. All the 100k resistors, good.
I removed all of the 460LC's but 1 in each circuit, turns on and works.
I determined that the reason for the shut down , was Pin 11 of the power supply driver was going to about 9.0 vdc (protect in). When it worked, it was .45 dc. This pin goes back to pin 12 of the 3s driver PCB.
Let me tell you the over current is real. I decided that I would try to remove the protection enable jumper that this amp has that removes pin 11 from tripping into protection. BAD idea, it blew up a set of outputs , replaced all the same parts on the 3 s driver.
I am able to scope the anode of d2, that's the diode on the 3s driver protect output, the cathode is output of the card to Pin 11 of the PWM driver. I see a brief pulse on the anode, that I believe is the result of over current. My 100amp supply reads 60 -102 amps when I attempt turning it on.
If I put the amp in slave mode, it turns on 8 of of 10 times, (I have 2 outputs in each section). I can put it into master, and it trips.
I was thinking it must be related to the audio in signal? but I power up the amp with external +/- 15 volts, feed audio into the RCA's and I follow audio all the way up to the second last TL072 before the Audio in of the 3s driver. The very last op amp (TL072), I do not see audio (pin1), but I can see its results on pin 18 (3s driver, mod out), as I change the volume level, the modulation changes.
I have replaced many of the TL072's, I replaced the (2) 12volt regulators -Rails, and the +/- 15 volt regulators. The 4.7uf capacitors CL1,CL5,CL6 and CL4, that are connected to the irs21844s.
It has a muting circuit, it appears functional, I did replace the G80s semiconductor, the gate drive signal to that on power up, is driven by the -15v regulator though an transistor RC network, I see it functional with about -7.45 to its gate. audio is muted, and after about 3 secs, enable.
At this point, it might be related to the 3s drive circuit, somehow, (unproven as of today), I am not sure a brief pulse isn't triggering the gate drive signal, Perry gave me an idea about using the scope in differential mode to measure gate drive. I am unable to hook my scope to -Rail. I am hoping I see a pulse, it's the only thing?
Thoughts, idea...young priest and an old priest???
I have done quite abit of troubleshooting and I need another brain. This is a Sampson 8K amp. It uses the 3S driver PCB (4 irs21844s), and (32) irfp460LC outputs.
When I got it, (4) of the 470's exploded, in all different parts of the output section.
So I did the usual, replaced all 4 drivers IC's and the 2D driver transistors. I installed 1 of the 4 irf460's in each circuit (instead of 4) for a total of 8, and turned on the amp. And it worked, power up and relays click.
I proceeded to install all the outputs, and discovered as soon as I powered up, it went into protection in about 2-3 secs. I was a bit confused, so I ohm'ed all the outputs, good. checked all the gates resistors, they are good. The (4) 2.2ohm, 47uh inductors, measure the LC inductors values (80uh) good. All the 100k resistors, good.
I removed all of the 460LC's but 1 in each circuit, turns on and works.
I determined that the reason for the shut down , was Pin 11 of the power supply driver was going to about 9.0 vdc (protect in). When it worked, it was .45 dc. This pin goes back to pin 12 of the 3s driver PCB.
Let me tell you the over current is real. I decided that I would try to remove the protection enable jumper that this amp has that removes pin 11 from tripping into protection. BAD idea, it blew up a set of outputs , replaced all the same parts on the 3 s driver.
I am able to scope the anode of d2, that's the diode on the 3s driver protect output, the cathode is output of the card to Pin 11 of the PWM driver. I see a brief pulse on the anode, that I believe is the result of over current. My 100amp supply reads 60 -102 amps when I attempt turning it on.
If I put the amp in slave mode, it turns on 8 of of 10 times, (I have 2 outputs in each section). I can put it into master, and it trips.
I was thinking it must be related to the audio in signal? but I power up the amp with external +/- 15 volts, feed audio into the RCA's and I follow audio all the way up to the second last TL072 before the Audio in of the 3s driver. The very last op amp (TL072), I do not see audio (pin1), but I can see its results on pin 18 (3s driver, mod out), as I change the volume level, the modulation changes.
I have replaced many of the TL072's, I replaced the (2) 12volt regulators -Rails, and the +/- 15 volt regulators. The 4.7uf capacitors CL1,CL5,CL6 and CL4, that are connected to the irs21844s.
It has a muting circuit, it appears functional, I did replace the G80s semiconductor, the gate drive signal to that on power up, is driven by the -15v regulator though an transistor RC network, I see it functional with about -7.45 to its gate. audio is muted, and after about 3 secs, enable.
At this point, it might be related to the 3s drive circuit, somehow, (unproven as of today), I am not sure a brief pulse isn't triggering the gate drive signal, Perry gave me an idea about using the scope in differential mode to measure gate drive. I am unable to hook my scope to -Rail. I am hoping I see a pulse, it's the only thing?
Thoughts, idea...young priest and an old priest???
I replaced the driver PCB with another one that I have. Did the same exact thing.
I can replace them. if you think that's what it maybe.
I can replace them. if you think that's what it maybe.
Sorry for the delay, I had two more amps with the same driver PCB. I repaired both amps and repaired the driver PCB's.
I installed the known working amps driver PCB in the HiFonics amp, same issue, instant protect.
I also removed the HiFonics amps driver board and installed it into the other 2 amps, and it also worked. So I can say, that it's not the driver PCB.
I installed the known working amps driver PCB in the HiFonics amp, same issue, instant protect.
I also removed the HiFonics amps driver board and installed it into the other 2 amps, and it also worked. So I can say, that it's not the driver PCB.
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