Alright, I've been lurking here for a few months trying to figure out what to do with my damaged Kicker KX700.5 and I've finally caved in and registered so I can ask for some help. I've read over a lot of Perry Babin's site, and I've read a lot of posts, but I'm not sure what to do next...
My amp was attacked by rainwater that leaked into my trunk somehow. Now, it's stuck in protection mode. So, I pulled it open and found (what I think is) a FET that was highly corroded, along with a few tiny resistors. Nothing else appears to be affected. I cleaned the corrosion off with acetone and alcohol. Then, I tried powering up the amp without any speakers attached and it still went straight to protection mode. I have a DMM, and I tried testing some FETs and resistors, but got pretty mixed up and wasn't sure if I was even identifying FETs properly. I'm hoping someone here can give me some tips on what to do....it's a bit overwhelming.
Thanks
My amp was attacked by rainwater that leaked into my trunk somehow. Now, it's stuck in protection mode. So, I pulled it open and found (what I think is) a FET that was highly corroded, along with a few tiny resistors. Nothing else appears to be affected. I cleaned the corrosion off with acetone and alcohol. Then, I tried powering up the amp without any speakers attached and it still went straight to protection mode. I have a DMM, and I tried testing some FETs and resistors, but got pretty mixed up and wasn't sure if I was even identifying FETs properly. I'm hoping someone here can give me some tips on what to do....it's a bit overwhelming.
Thanks
Can you send me a few photos off the damaged area and one showing the overall layout?
babin_perry@yahoo.com
babin_perry@yahoo.com
Ah, ok. That was where I was getting confused. I wasn't sure if polarity of the meter mattered or if I was supposed to be testing between all the legs (giving 3 combinations to test for a 3 legged part).
Alright, I tested them again and found around 5 that read ~0 ohms. I'm going to try more cleaning of the board around them (one is on the bottom row of transistors, and the others are on the top row), but I imagine that they are toasted. If so, I just read the numbers off the part and purchase replacements? Where do I purchase replacements? And do they all have to be the same batch? I read something about problems between batches, but I didn't understand it all.
Alright, I tested them again and found around 5 that read ~0 ohms. I'm going to try more cleaning of the board around them (one is on the bottom row of transistors, and the others are on the top row), but I imagine that they are toasted. If so, I just read the numbers off the part and purchase replacements? Where do I purchase replacements? And do they all have to be the same batch? I read something about problems between batches, but I didn't understand it all.
Hmm, I can't figure out what the deal is, but I got different readings on several of the transistors today (checked out OK today). Anyway, I desoldered 4 of them that all read zero ohms across the two outside legs. The part numbers are:
Top Row, 5th from right:
YG225N2
(NPN diagram)
35
Top Row, 6th from right:
YG225C2
(PNP diagram)
35
Bottom Row, 5th from right:
YG225N2
(NPN diagram)
35
Bottom Row, 6th from right:
YG225C2
(PNP diagram)
35
Top Row, 5th from right:
YG225N2
(NPN diagram)
35
Top Row, 6th from right:
YG225C2
(PNP diagram)
35
Bottom Row, 5th from right:
YG225N2
(NPN diagram)
35
Bottom Row, 6th from right:
YG225C2
(PNP diagram)
35
The rectifiers appear to be OK. Reinstall them.
Is there a surface mount transistor Q4 near the TL494 PWM driver IC (16 pins, surface mount)?
If so, is one pin of Q4 connected to pin 14 of the TL494 and another pin connected to pin 4 of the 494? Check for continuity with you ohm meter. You're looking for direct connection (~0 ohms).
Is there a surface mount transistor Q4 near the TL494 PWM driver IC (16 pins, surface mount)?
If so, is one pin of Q4 connected to pin 14 of the TL494 and another pin connected to pin 4 of the 494? Check for continuity with you ohm meter. You're looking for direct connection (~0 ohms).
The part labeled 'Q04' has an outside leg that is pointed towards the TL494 that is directly connected to 13,14,15 of the TL494. 'Q04' Also has a middle leg that is connected, via a '4R7' resistor, to pin 4 of the TL494. Checking resistance between these two legs on 'Q04' gives 24.9 kOhms. Checking resistance between legs 4 and 14 on the TL494 gives the same 24.9 kOhms.
Note, rectifiers have not been reinstalled yet - headed to the store to get more solder today.
Note, rectifiers have not been reinstalled yet - headed to the store to get more solder today.
The following will disable the protection circuits and could possibly cause more significant damage but without a full schematic, it's the easiest way to continue troubleshooting.
Do the following (after replacing the rectifiers).
Tightly clamp all components to the heatsink.
Insert a 10 amp in the B+ line before applying power.
Lift 2 legs (making sure that they are no longer making contact with the board) of Q4 or remove it. Note the numbers on top of it before trying to desolder it.
Power up the amp.
Does it go into protect or blow the fuse?
If it powers up and doesn't blow any fuses. Measure the DC voltage across EVERY pair of speaker terminals. All should have significantly less than 1v of DC.
Measure the DC voltage on the RCA shield with the black probe on the ground terminal of the amp. It should be less than 1v.
If there isn't any voltage where it shouldn't be, connect speakers and a signal source to the amp to see if it produces audio (at a low level - at high power, it will blow the 10 amp fuse).
Do the following (after replacing the rectifiers).
Tightly clamp all components to the heatsink.
Insert a 10 amp in the B+ line before applying power.
Lift 2 legs (making sure that they are no longer making contact with the board) of Q4 or remove it. Note the numbers on top of it before trying to desolder it.
Power up the amp.
Does it go into protect or blow the fuse?
If it powers up and doesn't blow any fuses. Measure the DC voltage across EVERY pair of speaker terminals. All should have significantly less than 1v of DC.
Measure the DC voltage on the RCA shield with the black probe on the ground terminal of the amp. It should be less than 1v.
If there isn't any voltage where it shouldn't be, connect speakers and a signal source to the amp to see if it produces audio (at a low level - at high power, it will blow the 10 amp fuse).
Q04 is tiny. I'm worried that I might damage it, or the board, with my soldering iron. Any tips on that? Possibly my $10 handheld iron isn't going to do the job here. Also, when you say a 10 amp fuse, is the standard amplifier fuse (like the three 30 amp green fuses shown on the circuit board) the right type to use?
Thanks much!
Thanks much!
You should be able to do it with virtually any soldering iron. Add new solder to the two legs on the bottom of the transistor so that the iron can heat both solder connections. When the solder has melted, lift that side of the transistor and remove the solder between the legs and the board.
Yes, an ATC/ATO 10 fuse will be OK.
Yes, an ATC/ATO 10 fuse will be OK.
OK, that means that you likely have a channel that's drawing too much current. Remove the small driver board (the one with the chips that have the numbers machined off of them) for the class D section. Does it blow the 10 amp fuse with that removed?
Are you 100% sure that you reinstalled the rectifiers back into the correct locations?
Are you 100% sure that you reinstalled the rectifiers back into the correct locations?
Rectifiers should be in the right locations - I kept them oriented so I wouldn't misplace them when they were off the board, but I'll double check the labels on the board versus the labels on the rectifiers. I'll also try removing the small driver board and get back to you on those two items. As far as Q04 goes, what do I do about getting a replacement? I figure it'll take a few days to ship, so I might as well order it.
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