I have a punch 200.2 (older model) here that i just got done replacing a channel and some power supply fets in. The bad channel had the irf540's and irf9540's replaced as well as the .1 ohm source resistors. Power supply just had the original ps fets(slips my mind what they were now) replaced with some huf75337p3's that I had on hand. All other ps components appeared to be good. After replacing all of what i thought were the defective components i put the board back into the heatsink and set the bias. After setting the bias I ran some sine waves through it and verified that I had output at the speaker terminals by using my meter to check the voltage(late at night when I finished up). Today I got the chance to run the amp to some speakers and at very low to low volume everything seems fine with the amp. Now when I try to run it at low to moderate volume or higher for some reason it makes my test head unit cut out/reset itself like power is getting unhooked and then hooked right back up . At the same time it is also making a clicking/popping sound through the subwoofer i was using for testing. I tried some different source material and no matter what i played i get similiar results.At this point I was thinking it was my test head unit so i hooked it up to another amp and then the problem went away. So something about this punch 200.2 is doing some weird stuff to my deck and itself. Its like it is somehow feeding back through the rcas into the head unit and causing it to shutdown. At no point does the amp ever shut off...just the head unit. My guess is there is a problem with the amps audio inputs but I'm not sure where to start looking
replacements for IRF540's were actually IRF540N's. Replacement IRF9540's are still 9540's. testing the amp on a bench power supply. I tried upping the voltage to 15 volts but it was no help.my supply is only 22 or 25 amps continuous but problem starts way before that amperage. power supply fets were blown but gate resistors and gate drive signal appeared to be good.
Reduce the power supply voltage to ~10v to force the power supply to go to full duty cycle. If the current draw doesn't increase when you decrease the supply voltage, the amp's supply is likely OK.
I've had 3 Rockford amps that wouldn't work properly with the IRF540N. One oscillated, one drew excessive current when driven to ~1/2 power (sounds like the same thing you're experiencing), the last one wouldn't power up (went into protect as soon as remote voltage was applied). In all 3 instances, I replaced the IRF540Ns with IRF540As (Fairchild Semiconductor) and they all worked properly with no other changes.
http://www.mouser.com/ProductDetail/Fairchild-Semiconductor/IRF540A/?qs=FOlmdCx%2bAA0MeqEvOvQtGw==
As a side note, the rest of those IRF540Ns worked properly in other (non-Rockford) amps.
I've had 3 Rockford amps that wouldn't work properly with the IRF540N. One oscillated, one drew excessive current when driven to ~1/2 power (sounds like the same thing you're experiencing), the last one wouldn't power up (went into protect as soon as remote voltage was applied). In all 3 instances, I replaced the IRF540Ns with IRF540As (Fairchild Semiconductor) and they all worked properly with no other changes.
http://www.mouser.com/ProductDetail/Fairchild-Semiconductor/IRF540A/?qs=FOlmdCx%2bAA0MeqEvOvQtGw==
As a side note, the rest of those IRF540Ns worked properly in other (non-Rockford) amps.
as long as I have to re order parts is there any problem with putting irf540's back in the amplifier? I just noticed that the IRF540PBF's appear to be a little cheaper but if there is an advantage of using the IRF540A i will just get those.Also curious to know if IRF9540PBF's are a problem or are they just the lead free version of a IRF9540? I purchased the IRF9540PBF's and they are currently in the amp. Just would like to know if I should swap those while I'm back inside the amp.
some differences between IRF540 and IRF540N FETs
Guys,
I was reading this thread with interest and thought I'd look over the datasheets for these two FETs. Comparing the International Rectifier datasheet for the IRF540N and the Phillips Semiconductor datacheet for the IRF540, I noticed that the input capacitance of the "N" suffix part is more than twice as high as the IRF540. I'd imagine that for a given gate drive circuit the turn-on and turn-off would be correspondingly slower with the larger input capacitance. If these were used in the power supply I could see how they'd possibly cause cross conduction if the deadtime wasn't long enough.
Perry,
In the audio output circuits do you suppose the larger input capacitance might also explain the oscillation you experienced? It'd be interesting to cut the value of the gate resistors in half to see if the oscilation goes away. I'm not sure if the circuitry driving the gate resistors would be OK with the larger load though.
Guys,
I was reading this thread with interest and thought I'd look over the datasheets for these two FETs. Comparing the International Rectifier datasheet for the IRF540N and the Phillips Semiconductor datacheet for the IRF540, I noticed that the input capacitance of the "N" suffix part is more than twice as high as the IRF540. I'd imagine that for a given gate drive circuit the turn-on and turn-off would be correspondingly slower with the larger input capacitance. If these were used in the power supply I could see how they'd possibly cause cross conduction if the deadtime wasn't long enough.
Perry,
In the audio output circuits do you suppose the larger input capacitance might also explain the oscillation you experienced? It'd be interesting to cut the value of the gate resistors in half to see if the oscilation goes away. I'm not sure if the circuitry driving the gate resistors would be OK with the larger load though.
ok so after using this amplifier in my car for a couple days to power a pair of tens another issue has presented itself. The amplifier plays cleanly and loudly but it is cutting out at higher volume. I get to almost maximum volume and it is fine but a couple clicks higher on the volume knob and the amp will cut out and in. It cuts out on the louder bass notes and comes right back in. I haven't watched the power light to see if it completely powers off or not but it happens so fast I don't think i'd really be able to tell. is there perhaps a damaged op amp that would cause this? The amplifier doesn't seem overly hot at all when this is happening and it will do it whether it has been playing for 15 seconds or an hour. I hooked up another subwoofer to see if that was the issue but the problem remains.
None of the source resistors were burnt however i did replace them anyways with some 1% source resistors that i saw you had recommended for the repair of a punch 200x2(boards appear to be identical) . I also checked those smd resistors as you had recommended in that same thread. They all appeared to be within tolerance. I will recheck them all once i get the amp back on my bench and maybe take a look at the other channel as well. Perhaps there is some problems over there even though it never failed
My one experience with cross conduction results in excessive noise on the outputs and a significant current drain.
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