right now, i have removed both the output fets and the audio module in order to repair it again.
Back to this amp.
I think of putting the module first as i can verify if some voltages are present.
Since the outputs are out of the circuit, i can be pretty sure they are ok.
I think of putting the module first as i can verify if some voltages are present.
Since the outputs are out of the circuit, i can be pretty sure they are ok.
First of all i want to verify if the voltages are correct without the module in, and without any signal feeding the amp.
1 -111
2 -134
3 -146
4 0
5 0
6 -146
7 0
8 0
9 -147
10 -111
11 -147
12 0.26
13 14.95
14 5.00
15 0
16 0
17 -5.00
18 0
19 -147
20 -111
21 -135
22 -147
23 0
24 0
25 -147
26 0
27 0
28 -147.4
29 -111
1 -111
2 -134
3 -146
4 0
5 0
6 -146
7 0
8 0
9 -147
10 -111
11 -147
12 0.26
13 14.95
14 5.00
15 0
16 0
17 -5.00
18 0
19 -147
20 -111
21 -135
22 -147
23 0
24 0
25 -147
26 0
27 0
28 -147.4
29 -111
With the module on, there are no significant changes in the voltages.
Only pins 1, 20 and 29 have -141V now (instead of -111V without the module).
I will proceed to soldering the fets.
Only pins 1, 20 and 29 have -141V now (instead of -111V without the module).
I will proceed to soldering the fets.
Unfortunately i have the same results all over again. The amp produced the 100Hz signal for about half a second.
Q9 is also blown, along with the bank that is driven by U1.
This time R271A (2R2/2W) is also blown).
I am ordering new parts.
Q9 is also blown, along with the bank that is driven by U1.
This time R271A (2R2/2W) is also blown).
I am ordering new parts.
I think that we need to confirm that all of the drive signals are good before you replace the outputs. You will have to repair the driver board and remove all of the outputs for testing.
Since there will be no carrier/oscillation, you will have to use something like a 9v battery to produce the high-side supply voltage so that you can check the signal on the scope. let us know when you have the driver boards repaired.
Did you check the diodes and capacitors on the high-side drive circuit for the driver IC that was driving the failed outputs?
Since there will be no carrier/oscillation, you will have to use something like a 9v battery to produce the high-side supply voltage so that you can check the signal on the scope. let us know when you have the driver boards repaired.
Did you check the diodes and capacitors on the high-side drive circuit for the driver IC that was driving the failed outputs?
very good topic! I have to go through all this with DD Z1a. By the way, I linked the failure of weekend IRFP360LC the unsuccessful party))) and was going to replace them with FQA24n50)))
Parts are here, i repaired again the module.
All outputs are off the board, now.
All regulators are are ok.
How do i check the drive signal now?
All outputs are off the board, now.
All regulators are are ok.
How do i check the drive signal now?
I've never done it on the amp you have but this should work.
The high side supply is generated by the pulses from the output transistors. Since you're testing with the outputs out of the circuit, there will be no supply voltage for the high-side drive circuit. Pins 11 and 13 are the supply pins for the high-side.
Connect a 9v battery with the negative terminal on pin 11 and the positive terminal on pin 13. I'd suggest inserting a 1 ohm 1/4w resistor in series with the battery in case there is a problem that tries to drive voltage back into the battery (or any other problem that could cause the battery to overheat).
Drive a signal into the amp. If you drive the amp with a strong 100Hz sine wave, you should see a 100Hz square wave on the gates of the high and low side FETs. The square wave should have rising and falling edges that are essentially perfectly vertical.
If you can't see the high side drive clearly, you may need to ground the input side of the output filter inductor to the secondary center-tap. If that's not connected to the amp's main ground, connect another jumper from the secondary center-tap to the amp's main ground terminal. That should allow you to see the high-side signal. It should swing from ground to about the voltage on the 9v battery.
While the test above will show you that the drive circuit is working at low frequencies, it won't tell you what it does at higher frequencies (like those of the carrier frequency). You 'may' be able to inject a higher frequency signal into the input pin of the driver board. A 100kHz signal should show you how the drive circuit will work when the amp is operating normally.
If you want to take it a bit farther, you can load the gate/source pads with a 1000pf capacitor. That will show you (to some degree) how the drive circuit will function with the FETs in the circuit.
If you're unsure if the waveforms are right, you could duplicate this with another driver IC and compare the signals.
If everything looks OK, monitor the high and low side drive while pushing on various parts of the board and the driver board. Do this while monitoring each of the gate pads for the output transistors. It only takes one intermittent connection to cause the amp to fail.
If the drive signals remain OK, you can reinstall the FETs.
Other possible problems:
* intermittently shorted inductor
* defective high-side supply components or broken traces. When you get the amp powered up initially, measure the voltage across pins 11 and 13 to confirm that you have the same supply voltage on the good and bad output sections.
The high side supply is generated by the pulses from the output transistors. Since you're testing with the outputs out of the circuit, there will be no supply voltage for the high-side drive circuit. Pins 11 and 13 are the supply pins for the high-side.
Connect a 9v battery with the negative terminal on pin 11 and the positive terminal on pin 13. I'd suggest inserting a 1 ohm 1/4w resistor in series with the battery in case there is a problem that tries to drive voltage back into the battery (or any other problem that could cause the battery to overheat).
Drive a signal into the amp. If you drive the amp with a strong 100Hz sine wave, you should see a 100Hz square wave on the gates of the high and low side FETs. The square wave should have rising and falling edges that are essentially perfectly vertical.
If you can't see the high side drive clearly, you may need to ground the input side of the output filter inductor to the secondary center-tap. If that's not connected to the amp's main ground, connect another jumper from the secondary center-tap to the amp's main ground terminal. That should allow you to see the high-side signal. It should swing from ground to about the voltage on the 9v battery.
While the test above will show you that the drive circuit is working at low frequencies, it won't tell you what it does at higher frequencies (like those of the carrier frequency). You 'may' be able to inject a higher frequency signal into the input pin of the driver board. A 100kHz signal should show you how the drive circuit will work when the amp is operating normally.
If you want to take it a bit farther, you can load the gate/source pads with a 1000pf capacitor. That will show you (to some degree) how the drive circuit will function with the FETs in the circuit.
If you're unsure if the waveforms are right, you could duplicate this with another driver IC and compare the signals.
If everything looks OK, monitor the high and low side drive while pushing on various parts of the board and the driver board. Do this while monitoring each of the gate pads for the output transistors. It only takes one intermittent connection to cause the amp to fail.
If the drive signals remain OK, you can reinstall the FETs.
Other possible problems:
* intermittently shorted inductor
* defective high-side supply components or broken traces. When you get the amp powered up initially, measure the voltage across pins 11 and 13 to confirm that you have the same supply voltage on the good and bad output sections.
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