PPI A600 in protect mode

[Sean Morrison]

I repaired this amp a few months ago with the help of this board and it had been working great. I've had it powering a single 10" JL W3 bridged mono at 4 ohms.

Last night was the first time starting the car after sitting for a couple weeks and I heard a high pitched whine from the back and thought at first that it was my fuel pump and that it seemed to be a tick louder than usual. I investigated and it sounded like it was coming from the sub. Then I looked in the trunk and saw that the "protect" light was on, in addition to the normal red LED.

Where should I focus my attention on troubleshooting this issue?

[brandes.cm]

Verify battery voltage is high enough and then check the outputs for shorts. Move on to the supply fets, if all measure ok, power it up and check rail voltage.

[Perry Babin]

Don't apply power without the bottom cover tightly clamped onto the transistors. If it has a shorted output transistor, it could cause significantly more damage if the transistors aren't clamped down tightly.

[1moreamp]

Shorted outputs for sure by my experiences.

And Perry is correct no power to the amp without some clamping method to hold the power devices to the sink when the bottom is off. Especially the regulators just after the diodes they heat up quickly and fail in short order with proper clamping.