Earthquake phd5000 red repair. Need help

[Vytautas1]

I trying repair this blown amp. Power supply mosfet stp80ne06, output stp50ne10. I think replace with irf3205z for supply and irfb4610. Are whey correct replacment? Power supply at this time not working, mosfet driver chip is dead.

 

[Perry Babin]

For the outputs, the only FET that I've seen that would work, universally was the IRF3710Z (Z is critical). Others may work but I haven't found any others that will work universally in 4080 based amps.

Any IRF3205 will work.

 

[Vytautas1]

Irf3710z works with hip, but for this amp i think they are to weak. Can they handle the power?

 

[Perry Babin]

How are they too weak?

 

[Vytautas1]

3710z current is higher(59vs50). So they are stronger? But this amp no way can have 3000rms at 2ohm

 

[Perry Babin]

Stronger isn't really a technical term. They handle more current and have a lower Rdson which will make them run cooler. They are what I've used. If someone else has suggestions, they should post them.

If the insulators are delaminating, expect a lot more work than normal.

 

[Vytautas1]

Yes, mosfets will be solded on aluminium pads. I will try with low temperature solder. Its very good thing for cooling but a lot more work. Hip is dead. So i am waiting driver chip and hip. I also tryed to power up supply without driver chip, but squere wave look like mess then mosfets are connected. I put only 4 mosfets. I heard that it should work without driver chip.

 

[Perry Babin]

Be specific. There are 3 ICs that can be referred to as drivers.

Are you referring the the TC4424?

 

[Vytautas1]

Yes tc4424. Sg3525a works, i have square wave

 

[Perry Babin]

Without the 4424, you risk damaging the FETs unless you jump input to output pins on the 4424. That bypasses the 4424 and drives the FETs.

 

[Vytautas1]

Yes i jumo inputs to outputs, but wave look good just for half second. I will check with new 4424 later

 

[Perry Babin]

What does it look like after 1/2 second?

 

[Vytautas1]

Look like a few sine waves mess. My osciloscope have low sample rate.

 

[Perry Babin]

That's likely due to it having a regulated power supply. As soon as the rail voltage reaches its target voltage, the duty cycle is reduced and the gate and drain waveforms change significantly. That's normal.

If your 12v power supply is adjustable, reduce the voltage and the pulse width will increase.

 

[Vytautas1]

Today i put new driver chip and 4 new mosfets, still the same. Square wave look good until capasitors charged. Without rectifiers power supply seems working good

 

[Perry Babin]

Do you understand what it means to have a regulated power supply?

 

[Vytautas1]

i just now saw your answer. I never had amp with regulated supply. It look to me like simple nonregulated supply. I reduced voltage to 8.5v and wave switched to normal square wave. So looks like supply working fine. Tomorow i put new hip and 4 mosfets for testing. Thanks for help

 

[Perry Babin]

The only requirement for a supply to be regulated is to supply feedback to the control IC. Otherwise, they can be identical in every way.

 

[Vytautas1]

I was looking for feadback but i dont see.

 

[Perry Babin]

See attached.