Hello everyone, I'm a new member so hopefully this is the proper place to put this and that the pictures show up. I am no stranger to car audio but don't know much about repairing amps. Anyways...
I bought a Kicker KX1200.1 Amp off ebay, and shortly after I resold it. Sure enough the buyer contacted me and said the amp would smoke when hooked up (I never hooked it up, stupid I know). Anyways I have the amp back and I took it apart, and sure enough there are some burnt spots on the inner shell and circuit.
I have pulled the circuit board out and I'll upload the pictures because I'm not for sure what I'm looking at. I am somewhat familiar with electronics, but I don't know a ton, so please bear with me. I also have a DMM with me for any testings I might need.
I've search tons of other forums and seen some similar things but I don't really know if my case is exactly the same or not. I believe I need to replace a few irf3205 units on the amplifier, but I don't know if that alone will solve the problem or if they are linked into the circuit and I will need to change something else. Or if these MOSFET units are all the same, or different resistance/impediance/size/etc. Hopefully someone can help out. Thank you in advance and there should be pictures under this if I did it correctly.
I bought a Kicker KX1200.1 Amp off ebay, and shortly after I resold it. Sure enough the buyer contacted me and said the amp would smoke when hooked up (I never hooked it up, stupid I know). Anyways I have the amp back and I took it apart, and sure enough there are some burnt spots on the inner shell and circuit.
I have pulled the circuit board out and I'll upload the pictures because I'm not for sure what I'm looking at. I am somewhat familiar with electronics, but I don't know a ton, so please bear with me. I also have a DMM with me for any testings I might need.
I've search tons of other forums and seen some similar things but I don't really know if my case is exactly the same or not. I believe I need to replace a few irf3205 units on the amplifier, but I don't know if that alone will solve the problem or if they are linked into the circuit and I will need to change something else. Or if these MOSFET units are all the same, or different resistance/impediance/size/etc. Hopefully someone can help out. Thank you in advance and there should be pictures under this if I did it correctly.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Remove all 8 IRF3205's and clean solder from mosfets via's as much as possible, leaving no solder bridges. Check DC voltages on the TL494 I believe it's U01. Black probe on power ground terminal and red to the following pins:
Pins
1)
2)
3)
4)
5)
6)
7)
8)
9)
10)
11)
12)
13)
14)
15)
16)
Post your results in this format.
Do you have an O-scope by any chance? Please post any questions you may have before doing something your not sure about, before you attempt making measurements on a live power amp!!
The following will be the next step, I got ahead of myself, I'm having trouble navigating my laptop and didn't want to have to retype what I had started. So,until you post your results, leave the rest for later.
You will need to change out all 8 of the IRF3205's,Q05 & Q11-1504GR(?). check all of the gate resistors-R16-R19 & R22-R26-100ohm sm(1206). and check that they are connected between the gate leg of mosfets and Q5 & Q11. Replace all mosfets form the same batch(match batch) and source your parts from mouser, digikey are some reputable electronics parts supplier.
Check the outputs IRF640's an IRF9640's,and rectifier diodes with an ohmmeter. you should read high middle to both outside legs and 33k ohm outside to outside legs on 640's and 25k ohm ouside to outside on the 9640's. the rectifiers will be high middle to outside and shorted outside to outside legs.
Pins
1)
2)
3)
4)
5)
6)
7)
8)
9)
10)
11)
12)
13)
14)
15)
16)
Post your results in this format.
Do you have an O-scope by any chance? Please post any questions you may have before doing something your not sure about, before you attempt making measurements on a live power amp!!
The following will be the next step, I got ahead of myself, I'm having trouble navigating my laptop and didn't want to have to retype what I had started. So,until you post your results, leave the rest for later.
You will need to change out all 8 of the IRF3205's,Q05 & Q11-1504GR(?). check all of the gate resistors-R16-R19 & R22-R26-100ohm sm(1206). and check that they are connected between the gate leg of mosfets and Q5 & Q11. Replace all mosfets form the same batch(match batch) and source your parts from mouser, digikey are some reputable electronics parts supplier.
Check the outputs IRF640's an IRF9640's,and rectifier diodes with an ohmmeter. you should read high middle to both outside legs and 33k ohm outside to outside legs on 640's and 25k ohm ouside to outside on the 9640's. the rectifiers will be high middle to outside and shorted outside to outside legs.
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Thanks for the reply! Unfortunately I do not have an O.scope, just a DMM. I have located all the components you mentioned to check, but I'm not sure about if this is what you meant with the Q05 and Q11, so I attached the following pictures.
All of the IRF640s and 6940s have the resistance that you suggested, and none of them look to have any damage/wear whatsoever. I am unsure about the resistors 22-25 and 16-19. I measured the resistance across each and this is what I found
R22 - 38ohm
R23 - 52ohm
R24 - 38ohm
R25 - 100ohm
and
R16 - 32ohm
R17 - 100ohm
R18 - 33ohm
R19 - 33ohm
I figured they would all read 100ohm, but then I figured they might be tapered together somehow or on separate parallel/series circuits, so I'm not really sure what the resistances should be.
I also have a question about the 8 MOSFET units. You mentioned to replace all 8, which I assume I am capable of, probably have to apply heat to the current solder and pop them out and then replace/solder (I'm new at all this, so please bear with me). Anyways, they all have individual numbers (that are different), and I don't know if they hold different values (of resistance/induction/transistion/ect)... Several of them have the plastic on the front melted and coated with ash, tried scraping it off to see the numbers but its impossible. Are all these MOSFET units the same and just have different numbers for ID purposes or are they actual different values to which I will need to find a schematic of some sort?
Thank you for your help!
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
All of the IRF640s and 6940s have the resistance that you suggested, and none of them look to have any damage/wear whatsoever. I am unsure about the resistors 22-25 and 16-19. I measured the resistance across each and this is what I found
R22 - 38ohm
R23 - 52ohm
R24 - 38ohm
R25 - 100ohm
and
R16 - 32ohm
R17 - 100ohm
R18 - 33ohm
R19 - 33ohm
I figured they would all read 100ohm, but then I figured they might be tapered together somehow or on separate parallel/series circuits, so I'm not really sure what the resistances should be.
I also have a question about the 8 MOSFET units. You mentioned to replace all 8, which I assume I am capable of, probably have to apply heat to the current solder and pop them out and then replace/solder (I'm new at all this, so please bear with me). Anyways, they all have individual numbers (that are different), and I don't know if they hold different values (of resistance/induction/transistion/ect)... Several of them have the plastic on the front melted and coated with ash, tried scraping it off to see the numbers but its impossible. Are all these MOSFET units the same and just have different numbers for ID purposes or are they actual different values to which I will need to find a schematic of some sort?
Thank you for your help!
Thank you for the additional link, I will check it out as a reference. I definitely don't mean to repost/spam anything with a previous thread, this is my first time taking an amp apart and I'm not 100% sure what all I'm looking at. Appreciate the help!
The Q5 & Q11 you point too are correct, they will need to be replaced. The gate resistors will not show 100 ohms until you remove All 8 of the IRF3205's, because some of the fet's are shorted you will get erroneous readings.
You can cut the fets out with a small pair of wire cutters, which can be purchased at any hardware store or Radio Shack. If you dont have a soldering iron a cheap 40 watt Weller, with a pencil tip and standard tip will do. RS carrys them and solder braid/wick or desolder tool are necessary to clean off solder.
If you are needing a tutorial on soldering, youtube will have some or Perry Babin's BCAE website is a good source for learning basic skills and repairing car audio.
You can cut the fets out with a small pair of wire cutters, which can be purchased at any hardware store or Radio Shack. If you dont have a soldering iron a cheap 40 watt Weller, with a pencil tip and standard tip will do. RS carrys them and solder braid/wick or desolder tool are necessary to clean off solder.
If you are needing a tutorial on soldering, youtube will have some or Perry Babin's BCAE website is a good source for learning basic skills and repairing car audio.
The 8 power supply FET's may be hard to read but they are all IRF3205''s. When you order them from a reputable supplier they should all be from the same batch from the chip maker(International Rectifier is the maker), and the markings reflect that and are date stamped with a code. Its good practise to use from the same batch.
BTW, I work for Kicker and have fixed a countless number of these amp, among others.I have schematics but cant offer them due to proprietary reasons. But, enjoy helping others fix their amps. Please bare with me, take it step by step and you will have a working amp! This is a good forum with a weath of info and advice from very knowledgeable techs.
BTW, I work for Kicker and have fixed a countless number of these amp, among others.I have schematics but cant offer them due to proprietary reasons. But, enjoy helping others fix their amps. Please bare with me, take it step by step and you will have a working amp! This is a good forum with a weath of info and advice from very knowledgeable techs.
I can't thank you enough for pointing me in the right direction. I only have one more question (for now). I'm sure i will be able to solder everything once I get the parts. I checked the digikey site you mentioned earlier and simply searched IRF3205, which gave me several results. Based off the pictures (matched it to what the ones on the amp look like) by the items I have it narrowed down to 2 results.
Both fets are described as N-CH55V, but one is 75A - 220AB, while the other is 110A - 220AB (says this in item description). The first number refers to the 'current continous drain', and they both have different Rds (on max) @ ID Vgs (6.5 and 8, respectively), input capacitance (3450pf @ 25V and 3247pf @ 25V), and max power (170watt and 200watt respectively). I am not familiar with what these numbers mean, is there a certain one I should get between the two of these (or look for another item), or does it not matter as long as I get all 8 from the same batch? Thanks again, and apologies for asking so many basic questions...
This is the website I'm looking at if nothing I just typed happens to make sense
FETs - Single | Discrete Semiconductor Products | DigiKey
Thanks again!!
I will look at what I have at work Monday and and get back to you.
In the meantime if you remove the burnt FET's,and Q05,Q11, whenever the mosfets blow out they are prone to collateral damage, and even though they check okay with an ohmmeter you will need to replace them.
Recheck the resistances of the gate resistors and check the resistance at the location around the missing mosfets, middle to both outside via's.outside to outside via's. and post results as such:
label via's as pins 1-2-3 and maintain left to right on all 8 mosfets, rotate board 180 degrees to measure other side, so that you are consistent with results.
Q12
Pin 1 to 2-
Pin 2 to 3-
pin 3 to 1-
Q13
Pin 1 to 2-
Pin 2 to 3-
Pin 3 to 1-
and so on...
after you have posted results I will advice on next step.
In the meantime if you remove the burnt FET's,and Q05,Q11, whenever the mosfets blow out they are prone to collateral damage, and even though they check okay with an ohmmeter you will need to replace them.
Recheck the resistances of the gate resistors and check the resistance at the location around the missing mosfets, middle to both outside via's.outside to outside via's. and post results as such:
label via's as pins 1-2-3 and maintain left to right on all 8 mosfets, rotate board 180 degrees to measure other side, so that you are consistent with results.
Q12
Pin 1 to 2-
Pin 2 to 3-
pin 3 to 1-
Q13
Pin 1 to 2-
Pin 2 to 3-
Pin 3 to 1-
and so on...
after you have posted results I will advice on next step.
Alright, I'm pretty sure I can handle that. I'm going to have to hold off on messing around with this board for a couple days, its finals week with school (monday - wednesday) so I'm going to be busy probably until Wednesday evening. Whenever I get time I will for sure remove those Fets and Q5/Q11 and get some resistances posted. Thanks again for the reply!
Thanks, I'm a pharmacy student... Used to be in an electromechanical engineering program 4 or 5 years ago, which allows me to at least think I know a little bit about electronics. I've always been interested in car audio since I had my first system back in high school... I just kind of mess around / buy / sell / trade stuff for the fun of it. Should have some time off soon to hopefully make some progress on this board before too long
MMBTA56LT1G ON Semiconductor | MMBTA56LT1GOSTR-ND | DigiKey
Above is a link to the equivalent for the KTA1504GR-Q05 & Q11. The MMBTA56LT1GOSCT-ND is what you'll need.
As far as the IRFB3205 either one will do, but the IRF3205PBF-ND would be my perference.
Above is a link to the equivalent for the KTA1504GR-Q05 & Q11. The MMBTA56LT1GOSCT-ND is what you'll need.
As far as the IRFB3205 either one will do, but the IRF3205PBF-ND would be my perference.
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