Memphis SRX1200D.1 protection circuit

[Don Hathcock]

High

side gate using X50 differential probe.

 

[Don Hathcock]

The high side is the ones heating up. That's where the IRF640s are.

 

[Perry Babin]

What's the true amplitude? It needs to be about 10-12v.

 

[Don Hathcock]

The low side is 12.8
The high side is 14.8

 

[Perry Babin]

They really don't look bad but it doesn't take much cross-conduction to cause heating.

This type of amp generally uses 10 ohm gate resistors. You have a couple of options, replace the gate resistors or the 640s with 640Ns. I think I'd start with the resistors.

 

[Don Hathcock]

I think I will change out the resistors. I have a hot air station so it won't take long.

 

[Perry Babin]

I'd use a soldering iron. I am NOT a fan of hot-air for most components.

 

[Don Hathcock]

I use it a lot. Just have to set your temp and air flow rate correctly. I don't want to take it out of the heat sink unless I have to. I do have some hot tweezers if I can get them in there.

 

[Don Hathcock]

Couldn't I just solder another 22 ohm resistor on top of the ones there?

 

[Perry Babin]

You could, to see if it makes a difference but as a final repair...