Rockford Fosgate Punch 250.2 cuts out when bridged

[chipper]

First I'd like to say I got this amp for $12.24 as non working on eBay when I got it today I connected it up and tried it in bridge mode and it just kept cutting out non stop I could barely turn the radio up barely up to 10 or 12 then it cuts out I checked all wires even the subwoofer it is 4 ohms 500 watts. I had a Punch 55.2 before this and it didn't cut out like this with the same deck. I connected a different source (mp3 player) and it still cut out. Maybe that's why it was sold as non working? But any idea what could be wrong with it? Bad output MOSFET???

[chipper]

Anyone? I did replace one of the rail filter caps with the same type same type and specs. Plus it's missing a filter cap for the power supply could this be causing it to limit power output? I checked output mosfets and they all checked out fine. I need more ideas on what to check.

[Perry Babin]

How low is the DC voltage at the power/ground terminals dropping?

Do both channels work perfectly if only one is connected at a time?

[chipper]

Originally Posted by Perry Babin

How low is the DC voltage at the power/ground terminals dropping?

Do both channels work perfectly if only one is connected at a time?

Like what do you mean? The voltage feeding the amp? I put it in my car and it would work good it would just cut in and out. But if I connect the speaker to one channel it will play with out it cutting out on me but if I turn it all the way up then it cut out. And yes both channels do work good I guess but when bridged it sucks. Do you think the missing capacitor could be the problem? It's 63 volts 330 muF nichicon. I just can't figure put what's wrong with it. Thanks for the reply!

[Perry Babin]

You need to confirm that you have sufficient power supply voltage. With your multimeter set to DC volts, the black meter probe on the ground terminal of the amp (not on the point where the ground wire connected to the vehicle) and the head unit on (so the amp will have remote voltage applied), touch the red probe alternately to the B+ and remote terminals of the amp. If the voltage is below ~11 volts on either the B+ or remote line, you need to check the wiring feeding whichever line is too low. If 'both' the B+ and remote turn-on lines are low and your battery is fully charged, you may have a bad ground connection.

If the voltage is OK at idle, drive the amp until it shuts off. Monitor the voltage to see if the voltage is dropping when the amp is driven hard.

[chipper]

Originally Posted by Perry Babin

You need to confirm that you have sufficient power supply voltage. With your multimeter set to DC volts, the black meter probe on the ground terminal of the amp (not on the point where the ground wire connected to the vehicle) and the head unit on (so the amp will have remote voltage applied), touch the red probe alternately to the B+ and remote terminals of the amp. If the voltage is below ~11 volts on either the B+ or remote line, you need to check the wiring feeding whichever line is too low. If 'both' the B+ and remote turn-on lines are low and your battery is fully charged, you may have a bad ground connection.

If the voltage is OK at idle, drive the amp until it shuts off. Monitor the voltage to see if the voltage is dropping when the amp is driven hard.

Sorry for such late reply! I was looking all over for my VOM. So I measured the voltage when I played it it goes all the way down to 11 volts and sometimes 10 and when in bridged it drops from 13 to 11 then it cuts off and on and won't let me do anymore further testing when bridged. I was using a battery with the charger on it. It also has a missing capacitor in the powersupply it is 63 volts 330 uF could this be affecting it?

[Perry Babin]

One missing capacitor won't generally cause a problem if there were others in parallel with it. Confirm that none of the others have broken leads.

What speakers do you have connected in stereo and in mono.

[chipper]

Originally Posted by Perry Babin

One missing capacitor won't generally cause a problem if there were others in parallel with it. Confirm that none of the others have broken leads.

What speakers do you have connected in stereo and in mono.

I checked all the others and they are all fine, there's supposed to be two of them but only one is there and I checked to see if it's probably coming off but it's fine and soldered on. I had a Rockford Fosgate Punch HE 12 on it it's a 4 ohm single voice coil sub I had my Punch 40 on it before this and it work fine but this amp won't hit it all I can't figure outs what's going on. I don't see or smell anything burned or odd looking in the amp.

Also even at a 2 ohm load on one channel it will still cut off but if I cranked it all the way. Could this be a shorted MOSFET, transistor, ic of some sort that's causing it not want to work at full potential? All of my wiring is 8 gauge even double checked fusing, connections at the batt and rem and nothing??? Please help.

[Perry Babin]

Is the condition of the battery good enough to start a vehicle?

If you connect a 2 ohm load to one channel at a time, does it shut down on both channels?

[chipper]

Originally Posted by Perry Babin

Is the condition of the battery good enough to start a vehicle?

If you connect a 2 ohm load to one channel at a time, does it shut down on both channels?

Yes it's a good battery that I bought a couple months ago as a spare.

Yes it'll shut off with both channels loaded with 2 ohms. But one thing I did notice when I wired one of my kickers in series for 8 ohm it played flawlessly but at 4 ohm it's a piece of sh*t I really don't get what's not letting it play at 4 ohm mono?? I even measured the resistance across all my speakers voice coils maybe I'd find one that was causing it to shut off and all my subs that I tested on this amp are 4 ohms and sometimes 3 ohms. I also played a 60hz tone on it and measured the output it was putting out 43 volts ac into 8 ohms mono!! Ahhh is that normal??? Thanks Perry!!