Earthquake 200DHC

[S Merlington]

I replaced the power supply fets in this amp (RFP50N06)

I also replaced the Outputs Orginals were STP50NE10 I replaced them with IRF3710Z

Also replaced the HIP4080


With just power and ground hooked yp the amp will draw excessive current..

Any ideas??

 

[Perry Babin]

Did you replace the 8-pin PS driver IC?

Do any of the PS FETs get hot if you power it up for a second?

 

[S Merlington]

I didnt replace the Driver IC (MIC4424CN)

Power supply fets get hot within 1 sec

 

[Perry Babin]

That IC generally fails. If the board is out of the heatsink, solder a jumper between the input and output pins for that IC (inA to outA, inB to outB). Remove the IC and see if it will power up. Again, be careful when applying power.

 

[S Merlington]

With them jumped and the IC Removed the amp powers up and idles perfectly

 

[Perry Babin]

Replace the driver IC. Don't forget to remove the jumpers.

 

[S Merlington]

This amp uses RFP50N06's as the power supply fets with 10 ohm gate resistors..


Is there a good sub for the fets since i burnt 2 of the new ones up..

 

[Perry Babin]

I'd use 3205s.

 

[S Merlington]

Can i use the 10 ohm gate resisors?

 

[Perry Babin]

Yes. I never replace them in earthquake amps and have never had any problems.

 

[S Merlington]

Power supply is up and running perfectly..

I stuck the output in the amp and they burnt up within a few seconds..

The Orginals were STP50NE10's IS it ok to replace them with IRF3710Z's ?

Also Not sure if the HIP4080 is defective or not but the diode solderd from pins 11 to 12 is shorted..

Also does this amp have negative rail voltage I only get positive rail voltage..

 

[Perry Babin]

Virtually all 4080 based amps use a single rail for the output stage.

I'd suggest replacing the 4080 any time that any output has failed.

Do you know why the outputs failed?

Did you check them before powering the amp up?

Did you ever power it up with the 4080 out of the circuit?

 

[S Merlington]

Not sure why the outputs failed..

I powerd the amp up with the hip4080 removed only after the outputs failed

 

[Perry Babin]

The 3710Zs are rated for less current than the original FETs but I know of no other FET that's likely to work.

For future reference, some 4080 amps lack pulldown resistors for the output transistors. Powering those amps up with the 4080 out of the circuit will cause the outputs to fail.

 

[S Merlington]

Ok i orderd new outputs (IRF3710Z's) and a new HIP4080

The 2 diodes (1N5234) 1 of them solders between legs 11 and 12 the other diode solders between Pins 19 and 20..

Are theese diodes just there to protect the IC ?

 

[Perry Babin]

I think the diodes are there to protect the FETs (maybe the IC) if the speaker wires are shorted to ground.

 

[S Merlington]

Installed the 3710Z's for the outputs put in a new HIP4080 And replaced the diode on the HIP4080..

Amp powers up and idles fine Produces audio but when i turn the crossover settings up the outputs is distorted..


Also the HIP4080 is getting hot within 1 min is this normal or not ?

I also have 0.38 volts measured directly across the output terminals If i try to mess with the DC offset pot it will increase to 30 volts but it wont go any lower so 0.38 volts is as low as i can get it to go..

 

[Perry Babin]

Post a photo of the distorted waveform.

The 4080s get warm but shouldn't get too hot to hold your finger on in a minute.

 

[S Merlington]

Scope is set to .5ms 1 volts/div

This is with a 200hz sine wave

First pic is taken with the probe touching the rca jack

2nd pic is on the positive output terminal

 

[Perry Babin]

Set the scope to 10v/div and post photos of the waveforms on both the positive and negative speaker terminals.