Hi guys
Again here, with odd little problem ...
I have this amp, it worked perfectly, but I was repairing another with similar characteristics (P500-2) which had burned the power fet.
Since I did not hand these fet, was the extracted with this unit (the, P400-4) for installation on the P500-2 which was repaired and works perfectly.
A few days ago I received new HUF75344 FETs and install them, I realized I made a big mistake when I drew the motherboard.
When Unsolder said transistors, in one, (Q1090) hole corresponding to the source pin, applied too warm, and the detached metal part circular motherboard, which is similar to a washer.
Then, reinstall the new power FET, the FET specifically to connect the amplifier, after four or five seconds, much heated ...
And my question is: is it possible that these motherboards have internal connections that are not seen with the naked eye?
Again here, with odd little problem ...
I have this amp, it worked perfectly, but I was repairing another with similar characteristics (P500-2) which had burned the power fet.
Since I did not hand these fet, was the extracted with this unit (the, P400-4) for installation on the P500-2 which was repaired and works perfectly.
A few days ago I received new HUF75344 FETs and install them, I realized I made a big mistake when I drew the motherboard.
When Unsolder said transistors, in one, (Q1090) hole corresponding to the source pin, applied too warm, and the detached metal part circular motherboard, which is similar to a washer.
Then, reinstall the new power FET, the FET specifically to connect the amplifier, after four or five seconds, much heated ...
And my question is: is it possible that these motherboards have internal connections that are not seen with the naked eye?
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For the high-current terminals of the power supply FETs, the traces are typically on either the top or bottom of the board. Do you see a large copper trace on the bottom of the board for that terminal?
No, Perry, no trace of copper is seen, not from the back or from the front of the motherboard.
Moreover, in the other FETs, this pin is connected to ground,
and not have any traces of copper by any of its parts.
Moreover, in the other FETs, this pin is connected to ground,
and not have any traces of copper by any of its parts.
It seems I still have problems ...
I replaced the four FET power with new ones, and re-soldered all connections, I have mounted the motherboard heat sink, with all screws, I connected the amp, but a few minutes a lot is heated, so much , you can not touch the heat sink, much also heated electrolytic capacitors power supply ...
I do not know which way to go ... I'm a bit lost ...
I replaced the four FET power with new ones, and re-soldered all connections, I have mounted the motherboard heat sink, with all screws, I connected the amp, but a few minutes a lot is heated, so much , you can not touch the heat sink, much also heated electrolytic capacitors power supply ...
I do not know which way to go ... I'm a bit lost ...
Which heatsink mounted transistors get hot the quickest?
What is the current draw while it's heating up at idle?
What is the current draw while it's heating up at idle?
If you connect only ground and remote, do you see a clean square wave on all 4 gate legs of the PS FETs?
The falling side seems a bit slow. Post 2 more images of the drive signal on the output of the PWM driver IC and on the side of the gate resistor that is not connected to the gate of the FET.
If you mean, Perry, to pin 11 of TL494C, which is the output of 5 volts, said outlet, I checked with the scope that has no waveform is a horizontal straight line.
Pin 11 is not the output .. Pin 11 of the 494 should have 12 volts on it ..
If I remember correctly its pin 9 and 10 that should show the drive signal
If I remember correctly its pin 9 and 10 that should show the drive signal
So I must have confused ... thanks for the info S Merlington.
Pin 9 is 0v
Pin 10 has 4,95v and linear wave form.
Pin 11 also has 4,95v and linear wave form....
Pin 9 is 0v
Pin 10 has 4,95v and linear wave form.
Pin 11 also has 4,95v and linear wave form....
Pin 14 is the 5v output.
Pin 11 is the 12v input for the internal driver transistors in the 494.
The waveform feeding the gate resistors looks OK. The other side of the resistor (gate leg of the FET) is probably OK. I certainly wouldn't expect 9 amps of current draw.
Try setting the bias pots fully counter-clockwise. Does that allow the amp to idle closer to 1 amp?
Pin 11 is the 12v input for the internal driver transistors in the 494.
The waveform feeding the gate resistors looks OK. The other side of the resistor (gate leg of the FET) is probably OK. I certainly wouldn't expect 9 amps of current draw.
Try setting the bias pots fully counter-clockwise. Does that allow the amp to idle closer to 1 amp?
Are you sure that you have a good clean drive signal on the gate leg of all of the PS FETs?
Do you read 0.000v across all 0.1 ohm source resistors in the output stage when the amp is powered up? You can use a current limiter to reduce the current draw and protect the heatsink mounted components.
Do you read 0.000v across all 0.1 ohm source resistors in the output stage when the amp is powered up? You can use a current limiter to reduce the current draw and protect the heatsink mounted components.
Yes, Perry, I rechecked the waveform on the pins of the door of the four Fet PS is the same as in the picture of post #8
In the 0.1 ohm resistors I can see, 28,45v and -29,15v respectively in each group for each channel of the output stage. (I do not see 0.000 v)
In the 0.1 ohm resistors I can see, 28,45v and -29,15v respectively in each group for each channel of the output stage. (I do not see 0.000 v)
Yes, Perry, sorry wrong ..
Reading between the pins of 0.1 ohm resistors is correct, I read 0.0 v
I do not understand what may be causing the amplifier to consume more than 9.5 A at rest ...
Can it be that the power FET I have been replaced defective or leaking?
Reading between the pins of 0.1 ohm resistors is correct, I read 0.0 v
I do not understand what may be causing the amplifier to consume more than 9.5 A at rest ...
Can it be that the power FET I have been replaced defective or leaking?
If the PS FETs were defective, it should show up on the gate leg signal since it doesn't draw excessive current with no remote.
For the readings, you'll have to use the full resolution. 0.006v may cause excessive current.
For the readings, you'll have to use the full resolution. 0.006v may cause excessive current.
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