Rockford Fosgate Punch 100x2

[nikb47]

Putting out 31.3v on right channel.

Measured outputs with black on leg 3
Q225
Leg 1 0v
Leg 2 .06v
Q215
Leg 1 0v
Leg 2 .06v
Q219
Leg 1 62.5v
Leg 2 0v
Q224
Leg 1 -62.5v
Leg 2 0v

Then measured with black on chassis ground
Q225
Leg1 -31.3
Leg2 -31.2
Leg3 -31.2
Q215 same as q225

Q219
Leg1 31.2
Leg2 -31.2
Leg3 30.6
Q224 same as q219.

What do I do next thanks in advance.

 

[Perry Babin]

Check the readings. Something isn't right.

First numbers, 219 and 224 should have the same voltages.

Second set of numbers. 219 and 224 have almost identical voltages but they were 60+v apart in the first numbers.

Do you read anything near 0 ohms between the legs of any individual output transistors (no power applied)?

 

[nikb47]

Changed q215 and q225
Now getting

Q215
L1 -27.4
L2 0
L3 -30.5
Q225 same

Q219
L1 27.3
L2 0
L3 30.5
Q224 same

But now putting out .065dcv how do I bring that number down?

Oh and I bought your tutorial earlier today, Perry. Thank you! Tons of info!!!

Skimming through it right now!

 

[nikb47]

Also I want to add that it seems like the output transistors are heating up very quickly!

 

[Perry Babin]

With all of the transistors clamped down, set the bias. The DC offset may drop. If it doesn't, I'd leave it as is. Getting it down could be as simple as replacing a couple of transistors but could be much more difficult to resolve. 0.065 is a bit high but will not cause any problems.

Is there a reason you didn't choose the download option for the tutorial?

 

[nikb47]

I did download it. Im looking through it right now! Must have taken you years to put all of the info together!

 

[Perry Babin]

I must have misread the notice.

Yes, years, especially for the various examples. Don't forget the files in the 'miscellaneousstuff' folder. Read the page 'Images and Notes for Other Amplifiers' in the directory very carefully to get the most from those pages.

 

[nikb47]

Ok sounds good. Im working on that ppi a404.2 right now. Actually waiting for parts right now. But I figured I could read through some of your usefull info while I wait. Any special sections to pay attention to for that amp?

 

[Perry Babin]

I don't have anything specifically on that amp. Any help would be generic. Navigate to the following page in the tutorial and read all that is there.

repair_tutorial/miscellaneousstuff/ppi/repairnotesprecisionpower.htm

 

[nikb47]

Hey Perry,

I let the 100x2 idle for about 1 hour and it got HOT! only on the right side by the output transistors. Do you know what could be the cause or what I can check? Thanks

 

[Perry Babin]

The bias is likely set too high.

Audio Troubleshooting page, item #s 39-42.

 

[nikb47]

Perfect! Thank you. Sorry I kind of feel like a nuisance. Lol Anyway... this is the very first amp I have ever attempted to repair. I started on it about 2 years ago. I was probing around on the power supply transistors and slipped and shorted one out. The amp went into the closet shortly after that. I had no idea what I was doing or what I was looking for. I just knew that it melted a door speaker haha. I started working on amps for friends just doing simple repairs like finding loose solders on some newer lanzar amps and junk like that. Now I am paying more attention and trying to learn more about this stuff. I find it pretty fun actually even though a lot of times I feel like pulling my hair out. Lol

So when I pulled it out again I knew that there was a shorted supply ic all I had that was close was an irfz34 thats whats in there now. Oh and that is on the left side. Now i cant seem to find the 36N06V anywhere. What is a good replacement for that transistor if you know off the top of your head? I guess thats it for know. Thank you.

 

[Perry Babin]

Start a new thread. Include the model number of the amp.

 

[seankane]

I use IRF3205 and 47 ohm gate resistors in these amps.

 

[nikb47]

Thats for this same amp. The RF 100x2. Sorry if I made it sound like a different one.

 

[nikb47]

Ok thanks Sean. Is there anything I can use that I won't need to change gate resistors?

 

[Perry Babin]

Yes. IRF3205s are generally used as subs in all Rockford amps that use the TO-220 case transistors in the power supply. If the gate resistors are greater than 51 ohms, I use the 47 ohm resistors. If the value is 51 ohms or lower, I generally use whatever the original resistors were.

 

[nikb47]

I was thinking the STP36NF06. It is very similar but the continuous drain current is only 30a instead of 32a would that make a whole lot of difference?

 

[Perry Babin]

Some amps are sensitive to the FETs used but the Rockford amps are not. The 3205 is very rugged. If you're going to be repairing amplifiers, you'll need to keep the 3205s in stock.

 

[nikb47]

Alright thanks guys. I'll order up a bunch of them. Should be all for this thread. Thanks again.