What's the voltage rating of the rail capacitors?
Photo of the components to the right of the fan?
Photo of the components to the right of the fan?
The attached diagram is pretty close to what you have. For the PS, I'd use IRF3205s with 47 ohm gate resistors. For the outputs, you might try the IRFB38N20D.
I’m trying to start up this amp power supply with 4 IRFZ44N (one each bank, uses 16 total), I have a solid drive circuit without none installed, but when the 4 is installed they get hot and the waveform degraded and seems wobbly. SG3525 is good and drivers (1027/1023 2ea) are 100 percent. Do I need to installed all supply FETs?
Am I having bad transformers?
Am I having fault along my DC rails on the audio circuit (I really don’t think it’s switched)
Is there bad rectifiers (uses 8pcs)
Someone was messing about the amp before so I’m not sure if I missed anything.
**I may have to isolate the power supply by pulling the anode/cathode and see its performance when I get back to it.
Am I having bad transformers?
Am I having fault along my DC rails on the audio circuit (I really don’t think it’s switched)
Is there bad rectifiers (uses 8pcs)
Someone was messing about the amp before so I’m not sure if I missed anything.
**I may have to isolate the power supply by pulling the anode/cathode and see its performance when I get back to it.
I'm assuming that you have the probe on 10x but the scope thinks it's on 1x and that's a 10v amplitude.
That would tend to mean you have a shorted transformer or something shorted after the transformer.
Does pulling the rectifiers change anything?
Do you have something you could use as a temporary heatsink (attached) or can you clamp the FETs to the amp's heatsink if you need to do more troubleshooting?
That would tend to mean you have a shorted transformer or something shorted after the transformer.
Does pulling the rectifiers change anything?
Do you have something you could use as a temporary heatsink (attached) or can you clamp the FETs to the amp's heatsink if you need to do more troubleshooting?
Attachments
Does pulling the rectifiers change anything?
I’ve pulled the B- bus bar from the amp, which I have to short to get the waveform, should I replace it and pull all the rectifiers and see?
I’ve pulled the B- bus bar from the amp, which I have to short to get the waveform, should I replace it and pull all the rectifiers and see?
Those are over-current shunt resistors, reinstall those. Having them out of the circuit can cause various problems.
Can you clamp the PS FETs to a heatsink?
Do you have a current limiting resistor?
Can you clamp the PS FETs to a heatsink?
Do you have a current limiting resistor?
I’ve added them back in the circuit, same waveform with the fets, and heat even tho I took out all the rectifiers. No proper waveform.
That amp looks like it has been wet inside.
I see lots of corroded solder joints and some white mineral deposits in the photos.
A good cleaning would certainly help, as the mineral deposits can be conductive and cause improper operation.
They can be removed with isopropyl alcohol and cotton swabs.
Corroded solder joints should be cleaned and resoldered as well.
Good luck.
I see lots of corroded solder joints and some white mineral deposits in the photos.
A good cleaning would certainly help, as the mineral deposits can be conductive and cause improper operation.
They can be removed with isopropyl alcohol and cotton swabs.
Corroded solder joints should be cleaned and resoldered as well.
Good luck.
Last edited:
I’m not seeing any corrosion that would inhibit it from working at this point and there are clean square waves been produced without the rectifiers in, but whenever the fets are installed they get heated all is there is the transformers, pull down resistors series with two poly caps. There’s no shorting across drain and source no open resistors, all vias terminate properly and all diodes in spec.