This amp had a pair of STW45NM60 outputs shorted at Q7 & Q8 when I got it.
So far I have replaced the two outputs, their 56 Ohm gate resistors, and a 3.9 Ohm resistor at R88.
On the DWM3640 audio driver board, I replaced U1 with an IRS21844 and Q6 & Q8 with MMBTA42's, although I don't think anything was wrong with the original transistors. I have not replaced Q2 or Q7 yet.
I have a 2 Ohm resistor inline with the B+. When I power the amp up, it drops to ~7V at the amp's power terminals and draws ~8A. The output relay does not engage, however when I attempt to measure the DC Voltage between the negative speaker terminal and the base of either Q6 or Q8 on the audio driver board it engages and stays engaged. Once it has done that, the amp produces a clean sine wave and has low millivolts of DC offset at the speaker terminal.
Another thing to note is, the amp's current draw reduces some, about 1A, when the meter probes are connected between the negative speaker output and the base of either Q6/Q8 and rises when removed.
Any tips on what to check next would be appreciated.
So far I have replaced the two outputs, their 56 Ohm gate resistors, and a 3.9 Ohm resistor at R88.
On the DWM3640 audio driver board, I replaced U1 with an IRS21844 and Q6 & Q8 with MMBTA42's, although I don't think anything was wrong with the original transistors. I have not replaced Q2 or Q7 yet.
I have a 2 Ohm resistor inline with the B+. When I power the amp up, it drops to ~7V at the amp's power terminals and draws ~8A. The output relay does not engage, however when I attempt to measure the DC Voltage between the negative speaker terminal and the base of either Q6 or Q8 on the audio driver board it engages and stays engaged. Once it has done that, the amp produces a clean sine wave and has low millivolts of DC offset at the speaker terminal.
Another thing to note is, the amp's current draw reduces some, about 1A, when the meter probes are connected between the negative speaker output and the base of either Q6/Q8 and rises when removed.
Any tips on what to check next would be appreciated.
When producing a clean sine wave (no load) does it draw 7-8 amps?
If so, which of the transistors on the heatsink are heating up?
If so, which of the transistors on the heatsink are heating up?
Today the amp is drawing less, ~6A at start up and settles at ~5.5A. Once I have engaged the relay, the amp draws ~5A while producing audio, no load. If I leave the probes placed between the negative speaker terminal and the base of Q8, the amp draw reduces to ~4A, but stops producing audio. The amperage readings have all been estimates from my analog panel meter from the Sorensen.
The relay seems to only engage if I touch the probes as described above and engages instantly. The voltage I measure between those two points begins at about -87.5V and climbs to about -104.5V and settles there.
After about 15 or so minutes of letting it run with the relay engaged, nothing seems to be getting hot or even warm in the amp. Nothing gets warm after letting it run without engaging the relay either.
When I adjust the power supply from 10VDC to 16VDC, the amp terminals measure ~6.25VDC, drawing 4A, and ~7.5VDC drawing 6A respectively.
The relay seems to only engage if I touch the probes as described above and engages instantly. The voltage I measure between those two points begins at about -87.5V and climbs to about -104.5V and settles there.
After about 15 or so minutes of letting it run with the relay engaged, nothing seems to be getting hot or even warm in the amp. Nothing gets warm after letting it run without engaging the relay either.
When I adjust the power supply from 10VDC to 16VDC, the amp terminals measure ~6.25VDC, drawing 4A, and ~7.5VDC drawing 6A respectively.
Morning Guys, the PG 1200.1 should have IRF360LC mosfets in the output stages not the devices you said you found there. So someone has replaced the original factory devices with something else. So this may be some of your problems right there.
Q7 and Q8 are the gate driver devices for the power supply PWM chip 2sb1260 as called out on my info driving the power supply mosfets which are 65NO6 devices.
This amp uses a PIC controller and if you do not have a load hooked up to the amp it senses a very high ohm load and runs the power supply in wide open throttle mode < I.E. every high rail voltages ~100+ volts > The PIC controller was meant to detect speaker loads when the amp gets power on and adjust the amp accordingly to get a maximum or 1200 watts no matter what ohm load you hook up to the amp, so that would be 1200 watts at 4 ohms or 1 ohm because of how the power supply operates < impedance protecting the amp sorta like JL but JL uses current sensing transformers to do this same protection, where as the PG uses electronic load sensing on the speaker terminals. >
So your gonna get odd readings if there is no load hooked up to this amp since its trying to load sense and power supply rail correct on start up. Expect it to do weird things looking to detect the speaker loads it expects to see. There was a factory trick that used a speaker delay relay so the amp did not see a load on fire up, but 6 seconds later the relays connected to speaker load and the amp ran unlimited into 2 and 1 ohm loads < every dangerous for the amps lifespan>. But it also produced huge power gains while not continuously possible it was possible to pulse this amp to over 2800 watts output like this. It just won't live very long doing this sort of thing since it was designed only to deliver 1200 watts at any load max output.
So this amp is very different inside on how it operates its supply rails to the outputs and power limit protection. So its apples to oranges to other amp designs you may be used to. I would start by making sure all the factory spec devices were in place inside the amp, then worry about how and what its doing after all that gets sorted out. The design does not allow for willy-nilly device replacement without re-engineering how the thing works. Just my humble 2 cents worth, but I hope it helps some...
Q7 and Q8 are the gate driver devices for the power supply PWM chip 2sb1260 as called out on my info driving the power supply mosfets which are 65NO6 devices.
This amp uses a PIC controller and if you do not have a load hooked up to the amp it senses a very high ohm load and runs the power supply in wide open throttle mode < I.E. every high rail voltages ~100+ volts > The PIC controller was meant to detect speaker loads when the amp gets power on and adjust the amp accordingly to get a maximum or 1200 watts no matter what ohm load you hook up to the amp, so that would be 1200 watts at 4 ohms or 1 ohm because of how the power supply operates < impedance protecting the amp sorta like JL but JL uses current sensing transformers to do this same protection, where as the PG uses electronic load sensing on the speaker terminals. >
So your gonna get odd readings if there is no load hooked up to this amp since its trying to load sense and power supply rail correct on start up. Expect it to do weird things looking to detect the speaker loads it expects to see. There was a factory trick that used a speaker delay relay so the amp did not see a load on fire up, but 6 seconds later the relays connected to speaker load and the amp ran unlimited into 2 and 1 ohm loads < every dangerous for the amps lifespan>. But it also produced huge power gains while not continuously possible it was possible to pulse this amp to over 2800 watts output like this. It just won't live very long doing this sort of thing since it was designed only to deliver 1200 watts at any load max output.
So this amp is very different inside on how it operates its supply rails to the outputs and power limit protection. So its apples to oranges to other amp designs you may be used to. I would start by making sure all the factory spec devices were in place inside the amp, then worry about how and what its doing after all that gets sorted out. The design does not allow for willy-nilly device replacement without re-engineering how the thing works. Just my humble 2 cents worth, but I hope it helps some...
Q6 and Q8 on the D class driver board connect to the SD inputs of each IR21844s chips so this might be why your loosing output when you take these to ground thru your meter, they also should have only +12 volt rails supply to them according to the info I have on hand. So grounding these thru your meter to the speaker grounds on pins 1 and 3 speaker terminals might just be inhibiting the amp operation nothing more IMHO.
The whole D class driver board only has +&-5 and + 12 supplied to it so anything else you might be reading would be questionable, and I would find the center tap of the power toroid secondary for any ground points for you negative probe of your voltmeter to connect to so your absolutely sure your referenced to center tapped ground of the supply < but this is just one of my many quirky ways of doing things lol >🙂
The whole D class driver board only has +&-5 and + 12 supplied to it so anything else you might be reading would be questionable, and I would find the center tap of the power toroid secondary for any ground points for you negative probe of your voltmeter to connect to so your absolutely sure your referenced to center tapped ground of the supply < but this is just one of my many quirky ways of doing things lol >🙂
Well, the output devices' solder joints look like everywhere else, so I assumed them original when I ordered my replacement set. It also had the original defaced driver IC's so if I understood correctly, those have to be replaced if the outputs go south. If someone replaced the outputs, they didn't finish the work.
This amp also has FQP85N06 installed in the power supply. Whoever worked on it before has great soldering skills, I guess.
Plugging in my test headunit and a 3 Ohm speaker did not change the amp's behavior at all. The relay does not engage on it's own.
I guess the next step is to source some new, correct output devices?
This amp also has FQP85N06 installed in the power supply. Whoever worked on it before has great soldering skills, I guess.
Plugging in my test headunit and a 3 Ohm speaker did not change the amp's behavior at all. The relay does not engage on it's own.
I guess the next step is to source some new, correct output devices?
Hi RiLoWa,
Yeah I understand your point, but I am reading this off a PG print my friend. And I have seen a few of these and the print info matches everyone of these I ever saw, albeit its been a while I was in full time business when these were new, and a few came in across my bench back then my friend.
I would start by sourcing and installing all the correct outputs. There for a while the IRF360LC was high priced and sort of hard to find so I am thinking someone has used ST brand STW outputs instead of good old reliable IR devices it was spec'ed with. These might be loading the gate drivers incorrectly causing your high idle current draw issues. < just maybe, as I have never seen them used in this amp I might be on a limb on this one but, it sounds possible >
Also the power supply gate drivers might not be matched since my print calls out for a lessor mosfet in the power supply also the gate capacitance might just be in left field for this supply to operate correctly. A simple test is to remove all the supply mosfets except one device for each primary coil and if the amp idles at lower power levels then the gate resistors might just be in left field for those 85 amp rated mosfets. < now I have seen this bunches of times > people swap fets thinking oh its just a fet and not taking into consideration how that fet in large arrays loads the gate driver circuitry, DOH !
Again I hope some of this helps but I don't think this amp will run right with incorrect devices inside of it. I have seen people try to beef up gear with throwing beefier fets inside of an amp, but in some cases not re-engineering the gate drivers will leave you with excessive current draw at idle conditions.
You can PM me if you like....🙂
Installing the correct devices in the power supply and audio output section has restored the amp to proper working order.
Thank you both for the help and information.
Thank you both for the help and information.
Hi all,
I have a PG X1200.1, when I got the amp, all the output/psu transistors were missing, so I bought the IRFP360LC & FQP65N06 as mentioned in this thread and installed them, upon powering up the amp it blew all 6 transistors on one side of the PSU. Physically can't see any other damage... any ideas what could be wrong?
I have a PG X1200.1, when I got the amp, all the output/psu transistors were missing, so I bought the IRFP360LC & FQP65N06 as mentioned in this thread and installed them, upon powering up the amp it blew all 6 transistors on one side of the PSU. Physically can't see any other damage... any ideas what could be wrong?
Both driver ICs on the audio driver board should have been replaced. I used the IRS21844. You may have defective outputs again. Other defects are possible as well, look for open resistors around the output section. Did you confirm all gate resistors were good for all FETs (power supply & outputs)?
I no longer have this amp so that's about all I can help you out with.
I no longer have this amp so that's about all I can help you out with.
Hi, the ICs on the driver board look ok, havent tested them. all the gate resistors measure 22 ohms...
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