kicker sx 1250.1 in need of repair

[relacsn]

New here. I'm having some problems with my amp. I was really impressed with the sx series so I plan to fix the one I have and add a 4 ch down the road. I have the sxrc remote control so I can control the amps from the drivers seat and keep an eye on voltages and temps. I had this amp installed in my Caddy pushing 2 10 L7s. It was mounted on a platform running in between the 2 boxes (one for each sub) about 2 inches above the floor in the trunk. Well this past winter my trunk started leaking and I didn't catch it soon enough. By the time I did catch it my 1"mdf had swelled to about 4 inches in some spots and my amp was "frozen" in a huge chunk of ice. :'( I pulled everything out. My subs tested fine (not at high volumes though). The amp on the other hand......I opened the amp up and found scorch marks around the 10 input mosfet's, with several of them having broken leads and one cracked in half. Half of these (5 on one side of the amp) had white crusty stuff on the back of the circuit board (looks like from the water???) And there is one other small spot that has this same stuff. I will try and get some pics up tonight. The mosfets are IRF3205 (top line). IR 507K (second line) 7Q 6J (bottom line). Now for my questions.

1. Is this amp going to be repairable? (I understand I may run into more problems but just from what I've said what's your opinion?)

2. Can I try to turn the amp on without the input transistors, just to test power? I remember testing it once before I opened it up but forget the results.

3. Are IRF3205 mosfet's what I need to replace or am I worried about the other markings? From international rectifier's website the second row is their emblem and the date it was made (507K doesn't make since then???) And the bottom row is the batch. I understand I want all 10 from the same batch so the tolerance is close. Any suggestions on a good US company to get these from?

4. There is a tiny chip resistor in front of each transistor, should these be replaced?

Thanks for all the help guys.

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[Timmothy Web 10+ year member]

got a picture of the board?

 

[Spooney 10+ year member]

Question 1: More than likely this amp is repairable. Just may take a lot of cleaning and tlc

Question 2: I wouldn't try to power the amp on. It may cause more damage. Sounds like maybe you had some vibration related failure as well with the legs having been broken off of some of the mosfets

Question 3: I would definitely replace the IRF3205's for starters but you will need to do more testing before you just swap those out and power the amp on. Some good US/North American suppliers for these parts are digikey,mouser,newark,arrow,avnet,future electronics,and maybe a few others but those are all pretty reliable suppliers. I usually get the best deal from arrow,avnet,and future but the fastest shipping from digikey

Question 4: Sounds like you are referring to the gate resistors possibly. I would definitely check them all. If they are still reading within tolerance than there is no reason to change them . If any single one were bad I would probably change them all so that they matched because i'm crazy like that but as long as the resistance is right they should be ok.

 

[relacsn]

How do I post pictures? I've tried several times and it says post denied, either the number of urls or something about key words is the reason. The pics are on photobucket and are public. There are 9 pics and my user name on photobucket is relacsn.

 

[relacsn]

 

[relacsn]

 

[relacsn]

Since these, I've used some denatured alchohol and qtips to clean the black stuff off the amp. I also removed the 10 mosfets on the input side. The last pic is of my setup. trial and error. I would not suggest firing the subs upward lol, these didn't hit near as hard as they should.

Thanks again

 

[relacsn]

Where the burn spot on the chips is where the leads broke. Q13 was split in two. Q14 looked fine. Of the resistors right in front of the mosfets 2 are the same and then 10 are the same out of 12. The extra two are stacked on the last mosfet on either side. They are stamped 473 and the rest are stamped 470. The ten read between 47 ohms and 47.6 ohms the two are 47 (yes 47 ohms) and 34.2k, which these should be 47k correct? I think these are prolly ok besides the 2 473's but I want to replace them all anyway. What steps should I take next until I can order the resistors and mosfets?

 

[relacsn]

Here are the mosfets. I think the leads more or less burnt off..?

 

[Timmothy Web 10+ year member]

u wanna fix your self?

 

[relacsn]

u wanna fix your self?

Yeah, prefer to but if its out of my league then ill have someone with a little more experience do it.

 

[akheathen Premium Member]

remember when measuring components in the circuit, you have to account for other components. if the pairs of 47k resistors were paralleled, then it should be reading about 23.5k.... personally, i replace the resistors even if they read good. you can get new smd resistors dirt cheap with your fet order, especially with higher quantities. i must have spent a couple hundred on irf3205pbf supply alone. they are about the best common fet you can get, imho, and use them as stability upgrades. first things first, go over the board with a fine tooth comb after the alcohol cleaning, and pay close to all of the electrolytic caps. they like the conditions you put it through the least of all, and can/will cause just the failure you have when they short out. it looks like at least one, if not both of the voltage regulators (the "KIA" ones) is cooked, and that supplies the regulated voltage to the control ic's, etc. also, test all the outputs for shorting (it actually looks like q131 has a tad arcing, but you always check, regardless) you need to find out what u05 was. all of this comes first, and i'm sure there may be a little more found, before applying power to take readings with no fets or outputs installed. if this is getting a bit too much already, you may be in too deep, especially if there is more than the outboard transistor and cap failures. you may be lucky enough, though, and not need much more. i would buy a few extra 3205's for testing with, just in case there is a problem when it is time to see if it will idle at different stages.