Turn on 12v car amplifier with ATX POWER_GOOD?


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Username: Banart


Post Number: 2
Registered: Sep-16
Does anyone know how to turn on a 12v subwoofer amplifier LM258, using the ATX power supply control wire for POWER_GOOD?

I am using an Azza model PSAZ-1000A14S, 1000 watt, single 12v rail, computer power supply so that a car subwoofer can be used indoors for parties. This already works great just using a manual toggle switch on the amplifer.

The power supply:

Amplifier wiring:

Opened the PSU and desoldered all unnecessary power wires for +5v, +3.3v, -12v, +5vsb, the 5/3.3v grounds, and miscellaneous ATX power plug wires. Combined the remaining +12v and Ground wires into two wire bundles, covered each with cable wrap from the original power supply cable groups, zip-tied the wrap ends, and soldered the +12v / Ground into an Anderson Power Products SB 175A disconnect plug with a propane torch.

For the box with the two LEDs, I am passing to it POWER_ON, POWER_GOOD, a +5v wire, a +12v wire, and a Ground wire.

Using at a dance:

lm258 pdf:
But I don't want the amp to be direct connected with no control. If the manual power switch is left on, and the amp tries to fully power up before the PSU is ready, then the PSU internal protection may crowbar itself, due to it assuming there's a dead short as it turns on.

I would like the PSU to turn on the amplifier automatically using the POWER_GOOD output. I think the add-on car amplifier expects a 12v signal from the stereo system, but don't know that for certain.

I already tried buying a tiny 5v relay (SRD-5VDC-SL-C) and directly connecting POWER_GOOD to it, to supply 12v to the amplifier power-on circuit, but there's not enough current from POWER_GOOD to activate the relay. It can directly light a LED however, as shown in the first video.

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