Rockford Fosgate Punch 200 IX

[S Merlington]

The power supply fets in this amp are shorted ..

The orginals are IRFZ40's with 51 ohm gate resistors..

Would the IRF3205's with 47 ohm gate resistors work or would the IRFZ44N's be better ??

The rectifiers in this are U1610 and U1610R would the U 1620 parts be good replacements since the 1610's have corrosion on them

Also wondering if a diode goes in D4's location ?

The board is marked PC-0696-B

 

[Perry Babin]

I'd use the 3205s. The 51 ohm resistors are OK if they're within tolerance.

D4 and D5 are 1N5366s. They're not critical and if they're defective, I generally remove them and leave them out of the circuit.

 

[S Merlington]

OK i replaced the Power supply fets , Also replace the 3 330 ohm caps..

Amp powers up and idle's perfectly and produces both + - rail voltages..

The amp is not producing the + - regulated 15 volts

Heres what i get on the 7815

Black probe on middle leg reg probe on 3rd leg :5.45

Heres what i get on all 3 legs when black probe is on ground terminal

Leg1:54.6
Leg 2:0
Leg 3:5.45

heres what i get on the 7915 with black probe on leg 1 and red probe on 3rd leg:0.87

Heres the voltaages on all 3 legs

Leg 1:0
Leg 2:0.72
Leg 3:0.87

Any ideas on where to check?

 

[Perry Babin]

The 7815 appears to be either defective or overloaded.

The 7915 appears to have a broken connection between it's center leg and the negative rail. You should have used the ground terminal as a reference, not leg 1. Confirm that you read 0 ohms between the first leg and the amp ground.

 

[S Merlington]

From leg 1 to amps groun i have 0 ohms

Replaced the 7815

Also double checked the middle leg to the negative rail for the 7915


Amp still does the same thing and has the same voltages

 

[S Merlington]

If I remove the 7815 on pad 1 i get 56 volts..

Do i need to track pad 1 back to see why i have 56 volts or is 56 volts normal ?

 

[Perry Babin]

I would expect about ±35v on the positive and negative rails.

What is the negative rail voltage?

 

[S Merlington]

I have no negative rail voltage..

The rectifiers are U1610 and U1610R

Would the U1620 parts be good replacement?

 

[Perry Babin]

The R version is the negative rectifier. The MUR1620CT is good for the positive rectifier and the MUR1620CTR is good for the negative rectifier.

 

[S Merlington]

OK replaced both Rectifiers in the amp ..

I have 55 volts of positive rail voltage on the outputs..

I have no negative rail voltage on the outputs but i have - 44 volts on the 1620R's middle leg but for some reson its not making it to the outputs..


I still have no + - regulated 15 volts on any of the op-amps ..


I also have 55 volts on the first leg of the 7815 ..

 

[Perry Babin]

The amp uses the voltage across both rails for regulation. Since there is no negative voltage, the positive rail is higher than it should be.

Are you measuring the voltage on all legs of the outputs to see if there is negative rail voltage?

If you don't have negative rail on any leg, it should be simple enough to follow the large traces to find the break.

55v on the positive regulator will probably damage it. It's only rated for about 40v.

 

[S Merlington]

Yes measuring all the legs on every output and get no negative voltage

 

[S Merlington]

Ok i found the broken connections as soon as i solderd them back together the 7915 went up in smoke..


SO the middle leg of the 7915 connects to the middle leg of the U1620R and the first leg of the 7815 connects to the middle leg of the U1620 correct ?

 

[Perry Babin]

Yes.

 

[S Merlington]

SO legs 1-3 or both rectifiers in this amp show 0 ohms between them IS that normal ?

 

[Perry Babin]

Yes. You're reading the resistance of the secondary windings.