What's wrong with this amp? PICS to SEE

[shizzzon 461]

Here is the situation, amp is irrelevant, here is the scene-

Stock alternator, car on, over 14v at idle, starting battery up front, XS D3100 batt in the back(reads 13.0 float), so i gots plenty of battery power for this amp which requires a 200A fuse.

I start to oscope the amp on a 48hz tone set to repeat.

Every now and then, there would be a "THUD" sound that would quickly come from the amp. Unknown as to why but we continue to scope anyway. I do not know if it's relevant or not.

Anyways, subsonic set to off, LPF set all the way up, bass boost OFF, phase 0, gain - all the way DOWN.

All settings on HU were flat, sub preout set to 15, Kenwood HU. Volume goes to 35.

I start the scoping process-

I want the user to reach a volume of 27 before i start turning up the gain.

Once he reaches approximately volume 20-22, this amp audibly appears to be outputting some decent serious power considering the gain is all the way down!

Once the volume is adjusted just a couple more notches, not even reaching 27 yet, here is what i know-

Voltage output on speaker leads- 28.5-28.7v (rated at 1.8kw@1ohm so not all the way there yet)

Sine wave on scope was still 100% clean.

immediately there was a "click" inside the amp as if something was switching then immediately smoke poured out the speaker wire\power\ground side.

The amp was extremely hot on the power\ground side.

Amp was taken apart and here are the pics-

Before i show pics, there was a chip that was cracked with model number - KIA494AP = Korea Voltage Mode PWM module Controller is what i pulled from it.

that and multiple FETs are fried, here are pics-

And of the Chip, looks like a resistor got fried too-

[shizzzon 461]

Well so far, I'm being told the SMPS has ruptured and may be the culprit of disaster.

I strongly believe this is purely amplifier failure but are currently uncertain as to why.

[emperorjj1 2]

mind if i ask why the xover was set so high? oh ya what drivers and what impedance was the setup?

the "chip" as you call it is the amp controller. the brain of the amp persay, the click was probably it blowing up and the fets blew with all that power

[slim2fattycake 85]

Someone suggested the PWM IC was defunct, replace with a TL494, and do the routine fet replacement. But he doesn't know why this happened.

Drivers = 2 10" Fi SSD dual 1 ohms.

More info here

http://www.caraudio.com/forum/showthread.php?t=420267

[Adrian_D 520]

If you want to start replacing just the parts that are obviously blown and this is your first endeavour, I suggest you to send it somewhere to get it repaired.

[Lucky 76 5]

im not saying that i am right by n e means ... i have troubleshooted a couple circuits and build a few cards at my work but i am just a second year intern at uconn as u already know ... to me it sounds like your IC - KIA494AP was either defective or damaged .... ICs are ESD sensative meaning even things like static can short them out ... i have done it a couple times with some op amps and ICs myself ... this would have either driven the mosfets past electrical capacity or driven them past their thermal capacity and blew them out ... a way you can test to see if that is really what the problem was would be to get the oscilloscope and a schematic of the board and figure out what the waves are supposed to look like at the IC's input .... if that was a gain control and you replaced all the mosfets you should be able to see that when measuring the output/s of the IC there should be a stable linear change ... another problem could be what is driving the KIA494AP ... if that cracked it could also be a possibility that the input is what killed it ... if you found that the input on the KIA494AP was scewed your problem lies before the cracked IC ... to test that you really need to have an in depth understanding of what the output voltages and curve structures of whatever is driving the KIA494AP

[Lucky 76 5]

also if you look at the picture of the IC - KIA494AP it seems that most of the blow was taken at pin 7 .... that is also where the crack is .... i looked up the data sheet on that IC from this website http://www.datasheetcatalog.com/datasheets_pdf/K/I/A/4/KIA494AP.shtml and it seems that pin 7 is ground ... usually a ground would blow out if there was a short of some sort in the chip so you might be good as far as that being the problem goes

[slim2fattycake 85]

How much would replacing all the fets and the PWM IC if that is all that needs replacing cost? Well how about how much does it cost in parts? I am not going to be doing the repair myself but may be able to get someone local to do it for me for a low price and all I have to do is buy the parts.

Also, what could make the chip short out like that? I doubt the chip was defective because I am the 2nd owner and the previous owner took good care of it and didn't have any problems to my knowledge.

Edited July 20, 2009 by phi

[Lucky 76 5]

How much would replacing all the fets and the PWM IC if that is all that needs replacing cost? Well how about how much does it cost in parts? I am not going to be doing the repair myself but may be able to get someone local to do it for me for a low price and all I have to do is buy the parts.

Also, what could make the chip short out like that? I doubt the chip was defective because I am the 2nd owner and the previous owner took good care of it and didn't have any problems to my knowledge.

ICs are very delicate and it was most likely an internal problem within the IC ... how old was the amp? .... like i said it could have also been ESD (electro static dischard) from just handling the amp (inside a shipping box with peanuts or plastic) ... anything is possible ... i do not know how much those parts cost ... i forget a website in which you can order that stuff from ... i know the website i sent you is for if you need to purchase in bulk i believe

[slim2fattycake 85]

Thanks. I'll have to send it to get repaired then.

[emperorjj1 2]

How much would replacing all the fets and the PWM IC if that is all that needs replacing cost? Well how about how much does it cost in parts? I am not going to be doing the repair myself but may be able to get someone local to do it for me for a low price and all I have to do is buy the parts.

Also, what could make the chip short out like that? I doubt the chip was defective because I am the 2nd owner and the previous owner took good care of it and didn't have any problems to my knowledge.

one thing i strongly recommend is you check up on how good of a repair shop or person or whatever you are taking it to. Because swapping parts is easy getting it so its fixed and working isn't so easy. If this guy just knows how to solder and thats it you may want to just have it fixed by someone who knows what they are doing. put in that controller backwards and holy shit

[Lucky 76 5]

How much would replacing all the fets and the PWM IC if that is all that needs replacing cost? Well how about how much does it cost in parts? I am not going to be doing the repair myself but may be able to get someone local to do it for me for a low price and all I have to do is buy the parts.

Also, what could make the chip short out like that? I doubt the chip was defective because I am the 2nd owner and the previous owner took good care of it and didn't have any problems to my knowledge.

one thing i strongly recommend is you check up on how good of a repair shop or person or whatever you are taking it to. Because swapping parts is easy getting it so its fixed and working isn't so easy. If this guy just knows how to solder and thats it you may want to just have it fixed by someone who knows what they are doing. put in that controller backwards and holy shit

ya let us know how it goes ... its also easy to tell which way the controller goes ... if u look at it there is a little notch, that is how you know what side is the beginning and then the side where the circle is closest to is pin 1 the go from left to right and that is 8 at the end, then ontop of 8 is 9 and then count right to left and the ending is pin 16

it would look like this

16 15 14 13 12 11 10 9

1 2 3 4 5 6 7 8

[slim2fattycake 85]

Right now I am going to bring it to Audio Sound, a local repair shop. I debated between dB-r and amp repair center as well but didn't want to mess with shipping/shipping costs.

Snoopdan has had some powerbass amps repaired at Audio Sound before for decent pricing so I'll try them because I won't have to pay to ship and they are like 10 mins from my house. Shizzzon thinks they are pretty knowledgeable as well. This is way out of my element to mess with. lol.

[sadistic 13]

the "chip" as you call it is the amp controller. the brain of the amp persay, the click was probably it blowing up and the fets blew with all that power

what is the input voltage of the amp for the rca inputs? you mite have done what the guy above me said if you were over the rate voltage buy a long shot like like using a line driver is what it looks like to me.

[shizzzon 461]

haha, if that happened then we can sue, lol

No, there's no way that happened.

The line voltage on the HU is 2.5v and the gain was All the way down!

I never had a chance to turn it up yet because the head unit never even got to the proper volume level to start adjusting settings.

[emperorjj1 2]

might have had the subs wire wrong or something. i know i blew my first amp by swapping one neg/pos on a quad coil mt. same exact thing happened. popped the controller and blew every one of the power supply fets

[Lucky 76 5]

if you are interested in a good repair shop you might want to check out CIA Engineering. I sent my amps out there and they are great. I tested my hifonics amp i got back from them after they replaced all the mosfets and I was able to turn the gains all the way up without clipping! (measured with an oscope) ... did i mention i was using a 4v rca input as well? ... great company, great prices, great service .... they also warranty their service ... they also send you a sheet of information on what was wrong and what could have caused it

[slim2fattycake 85]

Thanks but I think I am going to sell it. I don't want to fool with it anymore. Maybe someone that can fix it themselves can get a good deal on this amp.

Thanks for the help again. I have heard of CIA Engineering but didn't know they repair amps too.

http://www.caraudioclassifieds.org/forum/showthread.php?t=13976

[Lucky 76 5]

i want to buy it but i still dont have enough to finish what is in my car now =(

[emperorjj1 2]

ill take it

[slim2fattycake 85]

PM me emperorJJ1.