Is this amp finished? PICS of the inside. Please Help

[Chicago_one 10+ year member]

Background: I picked up this sub/amp/box combo on Craigslist pretty cheap. Yeah, yeah, you get what you pay for... so I took a chance. Owner assumed everything "Still worked".

12" Infinity Kappa, Kenwood KAC-7201 2 Channel, Q Logic Box. The amp already was missing the 2 30A fuses (can take that as a hint, something already went wrong in the past).

I installed everything with a StingPro 1 farad cap w/digital display and 2 new 30A fuses: I turn the car on, amp doesn't light up but the fan seemed to turn, cap activates and lights up. I shut everything down, hook up the sub, try again, turn on the radio and the fuses immediately blow.

So yesterday, I open up the amp bc I typically figure, if fuses blow as soon as power is put to them, theres an internal problem... right? I'm by no means a pro when it comes to internal issues, so I took pictures of what I thought looked odd. Can you help me out? I figure the white junk is no bueno... please help me elaborate and maybe I can fix this amp.

EDIT*** I can't post pics yet bc I'm new I guess.

So I'm finding a lot of white putty like substance around the little capacitors (I believe thats what those are) Seems to be oozing from the base of them. I can't see any crack or opening, but it surrounds the base on 3 of them. 2 are right near the ground/power terminals on the motherboard. One is near the center of the amp. Additionally, there are a few black, greasy areas on the backside of a couple resistors. If you think you can help, I can message you the pics, and hopefully be allowed to embed them in this post soon. Sorry for the hassle. ***

Let me know what you think from these photos. Like I said, I'm not a pro with issue like this at all, but I'd like to learn. Is there an obvious fix? Is this typical? Or should I toss this to the scrap yard and buy something else?

Luckily, that Infinity Kappa did test at 4.1 ohms on my DMM so I figure that's still good.

Click to read more...

 

[disturbed471985 5,000+ posts]

email pics to disturbed471985@hotmail.com and ill post for u.

 

[disturbed471985 5,000+ posts]

 

[Spooney 10+ year member]

The white substance around the base of those caps is there to hold them in place. Looks like they just used it on the larger ones. Totally normal for that to be there although a couple of the caps did look like they were bulging on the top which isn't good but I have seen them last a long time in that state as well. They may not be bulging at all but maybe the angle of the pics make them look that way . The "greasy" brownish stuff is flux and some of it may be left over from when it was soldered at the factory and some of it looks to be a result of the amp being ran hard. The flux isn't causing you any issues at this point. Its just looks ugly. A bottle of acetone and some Q tips will work wonders on that flux. You say the amp didn't blow the fuses until you powered it up or until you hooked up the subs? Thats almost certainly a sign of blown/shorted output transistors. If the amp nukes the fuses as soon as you install the power and ground cables(no remote turn on applied) then you have blown/shorted power supply fets

 

[Chicago_one 10+ year member]

Spooney - Thanks for the input. I have the equipment out of the car for now and am considering what to do with it.

But yes, correct. The fuses didn't blow until I hooked up the subs and supplied power, though the remote turn on Was connected. When I tried it before, without the subs connected, it sounded like the fan was engaging, but the power light didn't come on and the fuses did not blow.

Again, I'm a little new to the testing phase of car audio, but is there a way to test the transistors or power supply fets with a DMM? I have an Innova 3320 multimeter.

Is it possible to test

 

[Spooney 10+ year member]

Yeah you can use your meter to check for shorted outputs/power supply fets pretty easily if you know what you are looking for. Takes about a minute

 

[Chicago_one 10+ year member]

Ok. Thanks! I'll do a little research before I try anything, but I'll give it a shot.

 

[Spooney 10+ year member]

Check this out before you do anything: Basic Amplifier Repair

PM me if you have some questions

 

[Chicago_one 10+ year member]

Got around to checking what I could with my multimeter. Two of the Power Transistors (C4467) rated low at .006 and the other .002

Additioinally, two Diodes rated at a dead 0.00 (FML 22S / FML 22R)

From this, I can assume replacing these will help run this amp?

Two other transistors, closer to the RCA side of the amp rated around .48 - would these be good to use, or should I replace them as well?

OR, did none of this make sense and I'm just rambling and scratching down random readings?! lol I'm a little uncertain on my understanding of everything right now.

 

[Chicago_one 10+ year member]

Figured I would post a more direct look into this amplifier. I'm still unsure about my understanding of testing these components, but reading a lot on the Basic Amp Repair article Spooney posted (Great Resource) I think I'm testing these correctly. So here's what I'm finding, and I'll post my readings. If you have any insight, corrections, advice... please help.

The black, charred looking residue is lined up with the speaker terminals where the previous owner bridged the sub.

This small black area is the underside of Rectifier FML 22R (when tested, it read "0")

Diode Mode (Black on middle, Red on right) I got A1694: 0.484 / A1694: 0.484

Diode Mode C437: 0.808 / C4467: 0.6 / C4467: 0

B1548: .601 / D2375: .57 / FML22S: 0 / FML 22R: 0

Power/Ground/Remote terminals are located to the right of these ^^

Again, I'm not sure if I'm testing everything correctly. At one point, the reading on the rectifiers kept rising. Was I charging them or something? ** Looking back at my notes, I had the FML22S read at .396 at one point **

Opposite side of the Amplifier

FKV550 All read at 0.635

C4467: 0.523 / C4467: 0.523 / C437 .808 / A1694 0.611 / A1694 0.611

If this makes any sense to you, Please School Me! lol Or tell me I'm doing it completely wrong, I won't get offended. Just hoping to fix this and get a little thump in my 240. Thanks!

 

[phantom240 5,000+ posts]

****, getting all down and dirty in that amp. You've got more balls than I, lol.

 

[maylar 10+ year member]

I dunno how much help we can be remotely, but I'll try to give you a couple of tips. First do you know the difference between an NPN and a PNP transistor? And do you know how diodes and rectifiers work? Do you know what a P-N junction is? If not, then I would replace everything that reads less than 0.5V in diode test mode on your DMM. Those Japanese devices usually have "2S" prefixes - e.g. the D2375 is probably a 2SD2375.

If you understand basic transistor construction then download the data sheets on all those devices and check them in diode mode between emitter and colector and base and collector. You need to understand the polarity of the parts to be able to judge that, and you may have to remove (unsolder) them from the circuit to check them properly. The changing resistance you're seeing is probably capacitors charging.

The discolored circuit pads indicate heat. It's not necessarilly overheating but it shows parts that have gotten hot. Those would be the first ones I replace if I didn't know how to test them.

Good luck wit dat mang.

 

[Chicago_one 10+ year member]

Thanks Maylar.

Unfortunately, my understanding of PNP and NPN transistors is limited. I'm kind of learning as I go with this process, as it's the first time I ever tried to repair an amp. I appreciate your advice.

Do you have any good sources on where to buy replacements? Looking on eBay and they have pairs of A1694 and C4467 that I'll need to replace the channel, but they read a different number. For example, C4467 35 P... but the ebay ones are C4467 60 P. Are these ok to use, or should I go for something more specific?

Phantom240 - lol. thanks. I got the equipment very cheap, so I figure "shame on me" for thinking it would work with no problems, but if I can turn it into a functional amp again, bonus! As long as I don't invest too much cash into it, and I'll learn something new.

 

[Extreme1ont]

I am working on the exact same amp.. it belongs to a friend.

so he asked for me to check it out, the amp would turn on and after 10 seconds the light shut off and fan keeps going. i checked all his connections and even re done the ground wire and traced the power wire and redone connection at the battery. no difference.

I pulled the amp out to take it for the night and check it over, wired up into my own car and still does the same thing.

So.. with these connections.

Power

Ground

Remote

........

Nothing else connected, only the power. the amp will turn on and after a few seconds the blue power light goes out and fan keeps running. I tore it down and inspected it, tested everything with my multi meter and seems to be ok..

Im new to these repairs but i just finished replacing fets in a pioneer and is now working so im still learning lol...

Its not blowing fuses. simple just shuts off. i connected to my battery charger i think its 3AMP i use it for testing incase theres a shorted part the amperage is pretty low and wont do alot of damage. so i wired up my battery charger, connected the remote wire, after 5 seconds the power light is blinking and the amperage meter on my charger is maxing out but its rappidly bouncing up and down.

Im totaly stummped right now, im about to pull all the fets and output transistors and test them 1 by 1 with them all out and see what happens, but i think thats not the problem..

 

[TheUnderFighter 10+ year member]

In all honesty.... I would never have paid for anything you listed there :\ It's all pretty much rubbish.

Though your learning curve and work ethic to try to fix it are very admirable, it's a shame all the effort is going into such a crummy amp and sub and enclosure.

I certainly wish you the best of luck, I guess anyone has to start somewhere. Though if you do get it back to working condition I'd just sell it.