I have a concept amplifier in for repair with a blown powersupply. The audio section seems to be intact. All audio outputs check good with diode check. I rebuilt the powersupply and powered it up through a limiter. Powersupply seems to be stable. The audio section or rails stat to charge up and the amp goes into protect. Once it goes into protect the rail voltage on the outputs begins to drop. I did find to burn resistors bear the rca connector and LEDs that measure around 91 and 94 ohms so I am guessing these are 100 ohm resistors. Do these resistors being out of tolerance cause the protection circuit to trigger or could it be because of the current limiter?
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Would these 2 resistor cause the amp to go to protect or are they part of the protection circuit.
I think they're between the secondary ground and the RCA shield ground. If so and they still read near 100 ohms, I don't think that it could be causing the amp to go into protection.
Could the current limiting resistor I installed cause the amp to go into protect due because the rails are charging up slowly?
I don't know if this amp has low-voltage protection.
Do you see DC across ether channel when the amp tries to power up?
If you power up without the resistor, insert a 10-15 amp fuse in place of the resistor and clamp the FETs before powering up.
Do you see DC across ether channel when the amp tries to power up?
If you power up without the resistor, insert a 10-15 amp fuse in place of the resistor and clamp the FETs before powering up.
I will check for voltage on the speaker terminals after I replace the resistors near the rca connector.
With the limiter removed the power LED comes on and immediately pulls 60 amps and I pull wires off. With limiter in no dc voltage is measured on the speaker terminals. This amp has a tl494cn in the power supply
Is there a way to Bypass rail activation to look for the drive signal for audio section. Are these driver boards similar to the amp you posted a pic of earlier
You could pull the center legs of the rectifiers or desolder the inductor in front of the rectifiers. I don't know if the regulated voltages depend on the main rails so this may not work.
With all 4 rectifiers center legs pulled and the current limiter installed ( 2 ohm 100watt resistor), the m amp start pulling current.
Does twisting the transformer make a difference?
If you power it up for a second or two, which heatsink mounted components heat up?
Are the rectifiers shorted?
If you power it up for a second or two, which heatsink mounted components heat up?
Are the rectifiers shorted?
Okay so I reinstalled center legs and when I mentioned the powersupply. Was stable but in protect mode I was wrong. It pulls same current for 3 seconds and when it goes to protect then there is only voltage on the center leg to ground on the powersupply FETS.
