OK, so I purchased a used Memphis Audio Amp, ST1000D class D amplifier and upon connecting it to my two Memphis subwoofers, the green power light came on and everything seemed to be in working order. I hadn't even switched the subs on, through my head unit, when I started smelling he voice coils burning! I quickly disconnected the speakers and rechecked my wiring.
I am not a newbie as far as car audio installation so I checked and double checked, with my multimeter, that the subs were wired to have a final impedance of 4ohms at the amplifier.
The subs are 2 X 12" DVC 4ohm Memphis audio subs with a rating of 500 RMS each! This amp should have been perfect, in fact, I could have lowered the final impedence through the sub wiring but I know that this particular amp is a mono block amp with two sets of speaker connections, internal wiring drops the impedence to 2ohms.
So after double checking my wiring I tried again, this time the subs were fully extended and held in an upward position and the voice coils on both subs were fried completely!!! Anyway, what is the problem with this amp?
Can anyone suggest what to check first? I checked for any obvious burnt transistors or resistors but none of them seemed to be toast! I also used my multimeter to check the power FETS and the output transistors and they all read normal! I'm a little new at this amp repair thing so can anyone give me some advice a to what I should check next? It obviously is pushing out WAAAAY TOO MUCH DC CURRENT!
I am not a newbie as far as car audio installation so I checked and double checked, with my multimeter, that the subs were wired to have a final impedance of 4ohms at the amplifier.
The subs are 2 X 12" DVC 4ohm Memphis audio subs with a rating of 500 RMS each! This amp should have been perfect, in fact, I could have lowered the final impedence through the sub wiring but I know that this particular amp is a mono block amp with two sets of speaker connections, internal wiring drops the impedence to 2ohms.
So after double checking my wiring I tried again, this time the subs were fully extended and held in an upward position and the voice coils on both subs were fried completely!!! Anyway, what is the problem with this amp?
Can anyone suggest what to check first? I checked for any obvious burnt transistors or resistors but none of them seemed to be toast! I also used my multimeter to check the power FETS and the output transistors and they all read normal! I'm a little new at this amp repair thing so can anyone give me some advice a to what I should check next? It obviously is pushing out WAAAAY TOO MUCH DC CURRENT!
You said this is a "car audio" forum correct? Well, the last time I checked, memphis CAR audio ONLY make components for CARS
This is a CAR AUDIO amplifier and and actually, I did find the power FET transistors and 4X 22 ohm ate resistors had been blown! I actually checked every gate resistor and every power and output transistor prior to installing it in my CAR. They all read functional on my multimeter so what would have caused this?
I don't want to replace all of these transistors to have them all fry again! That's the extent to my amp repair knowledge, the transistors, the driver board, and the gate resistors. Anyone else that can actually help me with my CAR AUDIO AMP REPAIR situation would be greatly appreciated!
This is a CAR AUDIO amplifier and and actually, I did find the power FET transistors and 4X 22 ohm ate resistors had been blown! I actually checked every gate resistor and every power and output transistor prior to installing it in my CAR. They all read functional on my multimeter so what would have caused this?I don't want to replace all of these transistors to have them all fry again! That's the extent to my amp repair knowledge, the transistors, the driver board, and the gate resistors. Anyone else that can actually help me with my CAR AUDIO AMP REPAIR situation would be greatly appreciated!
Thank you for that helpful advice! I measured the speaker wire connections at the amps terminal for DC current and it measured 132 volts. Is this normal? I finally pulled the amp apart and I found the the IRF3205 FET transistors were in fact bad! None of the gate resistors were though? Isn't that uncommon?
I checked the output transistors as well and they too were bad! The concern I'm having is that prior to connecting these subs to the amp I checked with a multimeter and all output and power transistors were fine! The green power light remained on during this entire event as well! The internal fuses (2 x 40) blew but the protect light never came On! I'm worried that once I replace the power and both sets of output transistors, it will only repeat the same occurrence? What else could I check with the multimeter once the new transistors are in place?
I also have checked the driver board and found the 2 or 3 X A1266's were fried too! I dont own a oscillator so what other ideas can anyone give me to avoid frying ANOTHER pair of subs?
I checked the output transistors as well and they too were bad! The concern I'm having is that prior to connecting these subs to the amp I checked with a multimeter and all output and power transistors were fine! The green power light remained on during this entire event as well! The internal fuses (2 x 40) blew but the protect light never came On! I'm worried that once I replace the power and both sets of output transistors, it will only repeat the same occurrence? What else could I check with the multimeter once the new transistors are in place?
I also have checked the driver board and found the 2 or 3 X A1266's were fried too! I dont own a oscillator so what other ideas can anyone give me to avoid frying ANOTHER pair of subs?
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Thanks for responding Perry, I know your very busy but if anyone can help me figure this out, it's you!
I tested the DC voltage immediately after the subs went up in a smoke of glory The 3205's could've very well failed after I tested the voltage or I could've tested it incorrectly! Interestingly enough, prior to connecting the subwoofers to the amp, or installing it into the vehicle, I did a quick test with my multimeter.
I checked the 3205's and their gate resistors, the A1266's on the driver board, the ones that power the 3205's, and both sets of output transistors(9640's/640's), along with their gate resistors. Upon powering up the amp, remote wire attached, the green light came on. Still being inexperienced in amp repair, I assumed nothing was wrong when the green power light comes on! I shouldn't have trusted a 5 cent L.E.D. for an accurate assumption with a pair of $500 subs on the line, another expensive lesson learned!
Within 30 seconds of having everything connected, the subs fully extended upward, made a POP sound, and both voice coils overheated instantaniously! Unfortunately, the subs will require a complete overhaul to work again.
At this point, I've ordered all new 3205's, new 9640's, new A1266's and new 640's. I believe the two YG225C2 AND the two YG225N2's are OK, regardless, I can't find replacements for them anywhere??? Can ANYONE tell me if there is a new part#, interchangeable part, or even where I can find these?
Once I've replaced these parts, I will post my multimeter readings on this thread, using your very helpful work sheets perry, I want to be positive that I didn't miss anything, before applying power to the amp again! Is there anything I can test or check while I'm waiting on these parts? I do have an extra ST1000D amp that I'm using for spare parts and to compare multimeter readings.
I know these amps can be VERY unforgiving if powered up, even if only one bad component is overlooked! Please keep an eye on this thread Perry, I trust any advice and assistance that your willing to give. I can't begin to thank you enough for the VERY helpful tutorials that you've, so unselfishly, provided for the "average Joe". I should have all the new parts soldered onto the amp's board, no later than Saturday morning. Thanks in advance to ANYONE that takes the time to help!
I tested the DC voltage immediately after the subs went up in a smoke of glory
The 3205's could've very well failed after I tested the voltage or I could've tested it incorrectly! Interestingly enough, prior to connecting the subwoofers to the amp, or installing it into the vehicle, I did a quick test with my multimeter. I checked the 3205's and their gate resistors, the A1266's on the driver board, the ones that power the 3205's, and both sets of output transistors(9640's/640's), along with their gate resistors. Upon powering up the amp, remote wire attached, the green light came on. Still being inexperienced in amp repair, I assumed nothing was wrong when the green power light comes on! I shouldn't have trusted a 5 cent L.E.D. for an accurate assumption with a pair of $500 subs on the line, another expensive lesson learned!
Within 30 seconds of having everything connected, the subs fully extended upward, made a POP sound, and both voice coils overheated instantaniously! Unfortunately, the subs will require a complete overhaul to work again.
At this point, I've ordered all new 3205's, new 9640's, new A1266's and new 640's. I believe the two YG225C2 AND the two YG225N2's are OK, regardless, I can't find replacements for them anywhere??? Can ANYONE tell me if there is a new part#, interchangeable part, or even where I can find these?
Once I've replaced these parts, I will post my multimeter readings on this thread, using your very helpful work sheets perry, I want to be positive that I didn't miss anything, before applying power to the amp again! Is there anything I can test or check while I'm waiting on these parts? I do have an extra ST1000D amp that I'm using for spare parts and to compare multimeter readings.
I know these amps can be VERY unforgiving if powered up, even if only one bad component is overlooked! Please keep an eye on this thread Perry, I trust any advice and assistance that your willing to give. I can't begin to thank you enough for the VERY helpful tutorials that you've, so unselfishly, provided for the "average Joe". I should have all the new parts soldered onto the amp's board, no later than Saturday morning. Thanks in advance to ANYONE that takes the time to help!
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For replacement rectifiers, I generally use the MUR1620CT and MUR1620CTR.
Sometimes, driver board components on the audio output driver boards fail. There are low ohm resistors (1-4.7 ohms) that open. Sometimes the driver transistors fail.
If the driver boards are in sockets, remove the audio driver boards before applying power. If everything else on the board is OK, you should have ±rail on the 3rgd legs of the outputs and no voltage on the center legs.
Sometimes, driver board components on the audio output driver boards fail. There are low ohm resistors (1-4.7 ohms) that open. Sometimes the driver transistors fail.
If the driver boards are in sockets, remove the audio driver boards before applying power. If everything else on the board is OK, you should have ±rail on the 3rgd legs of the outputs and no voltage on the center legs.
Thanks Perry, once I install the new Power and output transistors, I will do exactly what you've suggested. At this point, I've removed both audio driver boards and the main driver board, yes they were the socket style. I do have two more questions while I'm waiting on the new transistors:
1.) Are the rectifiers something that usually go bad and should I be concerned with replacing these as well? What type of reading should I expect from my multimeter?
2.) Is there anything on the audio driver boards that I should be aware of that might possibly need replacing along with the A1266's on the main driver board?
Again, thank you so much for taking the time to help me out here, your knowledge is priceless!
1.) Are the rectifiers something that usually go bad and should I be concerned with replacing these as well? What type of reading should I expect from my multimeter?
2.) Is there anything on the audio driver boards that I should be aware of that might possibly need replacing along with the A1266's on the main driver board?
Again, thank you so much for taking the time to help me out here, your knowledge is priceless!
Ok, I installed all new output transistors, power transistors, I replaced the A1266's on the driver board, I checked the resistors and diodes that you mentioned, along with many other resistors/diodes on this board(gate resistors), I removed the audio boards from the sockets, and I measured the 3rd leg and center leg of the IRF9640's and IRF640's on both sides of the amp for +/- voltage, this is what I found:
With my multimeter switched to "20" the center reads 0 and the 3rd leg reads 0 as well. When I switch the meter to 200m the center leg reads between 0.05 to 0.09. The 3rd leg reads anywhere from NEGATIVE 0.02 to 0.09. This may be to low of a setting, I believe this is the "mili" setting. The question I have now is, when you said to power up the amp for these readings, I currently have a 12 volt source connected to the B+ socket on the amp, with a 10amp inline fuse to protect the power transistors from blowing again. I of course have the amp grounded to the chassis of my car but I have not connected the remote wire because I was concerned about blowing everything all over again!
Is the remote wire needed to test the center and third legs of the output transistors correctly? If I have to connect the remote wire, how will I protect the components from blowing again, IF there's an issue? Will the 10amp in line fuse and the two 30amp fuses inside the amplifier protect my newly installed parts?
FYI, the amp requires 2 X 40amp fuses, as I'm sure your already aware of, but I thought that if I lowered the amperage on the 2 fuses. Please advise me on what I should do next? I believe something is wrong with the way I'm attempting to take these readings? Thanks again Perry
With my multimeter switched to "20" the center reads 0 and the 3rd leg reads 0 as well. When I switch the meter to 200m the center leg reads between 0.05 to 0.09. The 3rd leg reads anywhere from NEGATIVE 0.02 to 0.09. This may be to low of a setting, I believe this is the "mili" setting. The question I have now is, when you said to power up the amp for these readings, I currently have a 12 volt source connected to the B+ socket on the amp, with a 10amp inline fuse to protect the power transistors from blowing again. I of course have the amp grounded to the chassis of my car but I have not connected the remote wire because I was concerned about blowing everything all over again!
Is the remote wire needed to test the center and third legs of the output transistors correctly? If I have to connect the remote wire, how will I protect the components from blowing again, IF there's an issue? Will the 10amp in line fuse and the two 30amp fuses inside the amplifier protect my newly installed parts?
FYI, the amp requires 2 X 40amp fuses, as I'm sure your already aware of, but I thought that if I lowered the amperage on the 2 fuses. Please advise me on what I should do next? I believe something is wrong with the way I'm attempting to take these readings? Thanks again Perry
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The 10 amp fuse won't offer much protection unless the current draw is extreme and it blows the fuse quickly. You need to clamp all transistors for the best protection.
Yes, the remote voltage must be applied.
You need to monitor the current draw when you power it up. It may initially draw significant current but the current draw should drop to about 1 amp after about 2 seconds. If it draws more than 2 amps for more than 3 seconds, there is likely a problem.
Yes, the remote voltage must be applied.
You need to monitor the current draw when you power it up. It may initially draw significant current but the current draw should drop to about 1 amp after about 2 seconds. If it draws more than 2 amps for more than 3 seconds, there is likely a problem.
I powered up the amp without the audio boards installed. At first, it went into protect mode but for the past few days, in my spare time, I replaced a few resistors and capacitors here and there that were bad! Tonight, I powered the amp up again, the amp clicked and the amp went from protect mode to the wonderful green light mode! I remembered that the LED doesn't mean anything so I calmed down and followed your instructions!
I took the DC voltage readings on the output transistors and while doing this, the amp let out a horrible squealing sound! I pushed the driver board closest to the RCA jacks down and although it was inserted all the way, the sound stopped.
The output transistors read different voltages depending on whether or not the squealing noise started up or not! I will tell you that while checking the DC AND AC voltage on the 16 pin TL494CN, whenever I touched pin 5,6, or 7, the squealing started again!
The readings on the output legs, as you asked me to get we're:
9640's:
Leg 1=-54 DC volts
Leg 2=+54 DC volts
Leg 3=-54 DC volts
640's
Leg 1=+52 DC volts
Leg 2=+52 DC volts
Leg 3=+52 DC volts
These readings were taken with a limited power supply too, the readings may have been higher with a full 12V applied
When I installed one audio board, nothing happen that I could tell!
When I installed the second audio board, the amp started squealing bad and the red and green LED lights were lighting back and forth like it couldn't make up its mind whether or not it was gonna go into protect mode or go green!
Please advise about what I should check next, what typical causes the squeaking near the voltage regulators/CT11-D12S(RELAY?)? Thanks again Perry!
! I remembered that the LED doesn't mean anything so I calmed down and followed your instructions! I took the DC voltage readings on the output transistors and while doing this, the amp let out a horrible squealing sound! I pushed the driver board closest to the RCA jacks down and although it was inserted all the way, the sound stopped.
The output transistors read different voltages depending on whether or not the squealing noise started up or not! I will tell you that while checking the DC AND AC voltage on the 16 pin TL494CN, whenever I touched pin 5,6, or 7, the squealing started again!
The readings on the output legs, as you asked me to get we're:
9640's:
Leg 1=-54 DC volts
Leg 2=+54 DC volts
Leg 3=-54 DC volts
640's
Leg 1=+52 DC volts
Leg 2=+52 DC volts
Leg 3=+52 DC volts
These readings were taken with a limited power supply too, the readings may have been higher with a full 12V applied
When I installed one audio board, nothing happen that I could tell!
When I installed the second audio board, the amp started squealing bad and the red and green LED lights were lighting back and forth like it couldn't make up its mind whether or not it was gonna go into protect mode or go green!
Please advise about what I should check next, what typical causes the squeaking near the voltage regulators/CT11-D12S(RELAY?)? Thanks again Perry!
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