Anyone have a high resolution picture of the DWM 3640NHV_30 with possibly containing the IC markings not scratched off?
Even more important I need a picture of the back side of the board, I believe there is a broken trace but want to make sure before I fix it.
I know what they are but was hoping to get a good picture to be sure of them being placed on the board right. The board I have doesn't contain the indicator marking for proper placement ether.
Even more important I need a picture of the back side of the board, I believe there is a broken trace but want to make sure before I fix it.
I know what they are but was hoping to get a good picture to be sure of them being placed on the board right. The board I have doesn't contain the indicator marking for proper placement ether.
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Well the large ICs are IR21844S, the two ICs in the middle are LM311 and TL072 if I remember correctly. But its been awhile so my memory is fuzzy, and i have never recalled ever replacing any of those parts on those amplifiers, Exception is the IR21844S when the outputs fail.
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I know that U1 (IR2144S) is placed 180 degrees with pin 1 toward the bottom of the board and U2 (IR2144S) is placed right-side up with pin 1 towards the top of the board.
I am more concerned about the U3 (TL072) and U4 (LM311) if I am not mistaken.
Are these placed normally? As in pin 1 toward the top of the board and the markings right side up?
I am more concerned about the U3 (TL072) and U4 (LM311) if I am not mistaken.
Are these placed normally? As in pin 1 toward the top of the board and the markings right side up?
Ehh... that i couldnt tell you, the only amplifier I had here that used this configuration was an MB Quart Discus, and its fixed, gone, and out the door but it uses the same exact guts as to what your working on.
Only person that might have an answer is Perry. I have done literally hundreds upon hundreds of amplifiers that use this design, but I cant remember the driver layout as I never needed to. it never fails. Only thing that fails is the Gate drive ICs.
Yeah, I must be the unlucky one to have received this one with a big black bubble smack dab in the middle of the LM311 lol. This IC is pretty much destroyed :/
And that is a comparator and likely generates the PWM signal that goes into the IR21844S, which means the IC failed all the way back into the input stage. However there are usually level-shifter transistors in between so thats likely NOT the issue.
which only leaves 1 other scenario: that LM311 is used in in the feedback/protection and if there was strong DC on the output, it could have killed the IC and maybe associated resistors.
I have learned with class D amplifiers over the years, any of them that fail with strong DC on the output, or had strong DC on the output, is to check everything in the protection circuit, and feedback circuits. Usually its safe, but there are rare cases that the strong DC kills it.
Come to think of it, I am working on a DD Z1A which is basically the same thing, except it has 4 IR21844s instead of 2. And its kicking into protection at first power-on. But if i soft-start it (tricking protection/overvolt circuits) it works fine. Go figure.
which only leaves 1 other scenario: that LM311 is used in in the feedback/protection and if there was strong DC on the output, it could have killed the IC and maybe associated resistors.
I have learned with class D amplifiers over the years, any of them that fail with strong DC on the output, or had strong DC on the output, is to check everything in the protection circuit, and feedback circuits. Usually its safe, but there are rare cases that the strong DC kills it.
Come to think of it, I am working on a DD Z1A which is basically the same thing, except it has 4 IR21844s instead of 2. And its kicking into protection at first power-on. But if i soft-start it (tricking protection/overvolt circuits) it works fine. Go figure.
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I found Perry's photo @
http://www.diyaudio.com/forums/car-audio/219527-driverboard-question.html
I love fixing these amplifiers. At first was like a giant puzzle but now learning from you guys here at the forums it is becoming much more clear in understanding how everything works. Thank you for your input that helps me a lot and now I know where to look and what to check. Understanding why something has failed is half the battle 🙂
http://www.diyaudio.com/forums/car-audio/219527-driverboard-question.html
I love fixing these amplifiers. At first was like a giant puzzle but now learning from you guys here at the forums it is becoming much more clear in understanding how everything works. Thank you for your input that helps me a lot and now I know where to look and what to check. Understanding why something has failed is half the battle 🙂
Ok, that particular board uses the dual comparator LM293 Instead of the single comparator LM311
Its not so much a puzzle to me anymore. I do run into the tough dogs from time to time and it really wracks my brain. But as far as puzzles? nah, not anymore. lol. But that comes with experience I guess.
Its not so much a puzzle to me anymore. I do run into the tough dogs from time to time and it really wracks my brain. But as far as puzzles? nah, not anymore. lol. But that comes with experience I guess.
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Judging from the smd codebook it is likely a zenner. X2 appears to be the label and 6N most likely the date code.
The SMD Code Book
It is a driver for EMPHASER EA1800D amps, I replaced all the parts and put the plate when light is an IDF 21844, even replaced the D1 ...
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