Stetsom 5k

[Threedengineering]

Hi everyone

I'm new to the forum and hope someone can help.
Bought a stetsom 5k, one of the older gen ones, bought it as a faulty unit with the hope it would be an easy fix.
Everything on the board measures fine, no blown ps fets, no blown outputs, amp has never been touched.
Amp powers on, blue light, builds good squarewaves on the transformer primaries, as soon as it reaches full duty cycle the amp shuts down. I then get solid red led for about 5 seconds followed by 3 flashes of red led.
I see nothing wrong with any components, been through just about everything on the board.
I'm using a 30A regulated bench supply at around 13v so don't think it's a power or low voltage issue.
Current draw at startup is around 5-6A

[caraudioguy2100]

Try pulsing the remote wire a few times at start up to build rail
Voltage and see if that works .

[Perry Babin]

Look up the owner's manual to see what the blink code indicated.

Post a photo of the board in the amp.

[Threedengineering]

It builds rail voltage, the amp turns on but as soon as it gets to full duty cycle on the power supply and max rail voltage it shuts down. According to the online manual the fault code is low voltage. I've powered it up from a 30A supply and even powered it from my battery bank, it does the same thing, supply voltage or current are definitely not an issue.

[Threedengineering]

This is the board

[Perry Babin]

What sort of signal do you see on the output filter inductors (check both terminals of each one) as the amp tries to power up?

[Threedengineering]

I get square wave on one side of both of the output inductors, nothing on the other side of the output inductors

[Perry Babin]

That means that the amp likely has only a minor problem. I don't have a diagram for it. Let's see if someone has more experience with this amp or has a diagram for it.

[Threedengineering]

I think so too Perry, I have repaired a few of these stetsom amps but have never seen anything like this before, I see the 4427 drivers on the power supply have been replaced or maybe just resoldered, the ps fets have never been replaced so I don't know why the 4427's were replaced. I've seen these amps use an ir4427 or the ucc27524 this amp has the tc4427 I don't suppose that may be an issue?

[Perry Babin]

It looks like the UCC ICs might work as long as the two enable pins are allowed to rise to more than about 2.5v.