kicker kx 650.4

I have a KX 650.4 that appears to be electrically dead. The amp has seen limited use and has never been abused. It worked one day,and the next day it didn't. I've checked the two 40 amp fuses in the amp and neither was blown. No led's are lit up. I pulled the amp to bench test it,as best that i was capable of. I did a close inspection of the circuit boards and didn't see any obvious signs of burns,scorching,etc. I didn't see any obvious broken solder joints on the board,but i didn't remove the board from the heat sinks for a closer look either. I powered up the amp and made sure that there was 12 volts thru the fuses and on the remote lug and figured this was my stopping point. I have an extensive background in electrical process controls,but a  somewhat limited knowledge of intergrated circuitry,the components,their electrical values,properties and basic function. If someone has a better understanding and can point me to the next step in diagnosing the failed part it would be greatly appreciated. Or possibly recommend a  reputable repair facility in the Dallas,Tx area. Thanks.Terry

Do not take the amp apart yet.  In the following picture the 2 clamps to the left of the picture do need to be removed.  Top left and bottom left clamp.  With the amp disconnected, meter set to the diode test function.  Below is a picture of the symbol that should be on your meter somewhere. 

Touch and hold one lead to the positive terminal of the amp, now touch the metal tab of one of the transistors that were uncovered by removing the clamps.   Do one transistor on top of pic and one on the bottom of the pic.  It should beep at you and read very near 0.000.  Now touch and hold one lead to the negative terminal of the amp, other lead to the rightmost leg of the same transistors you checked the tab of earlier.  Looking at the transistors when you can read the letters and numbers on the part is how you determine the rightmost leg.  Let me know what you find out. 

You did use a volt meter to verify that you had power on both the remote and power terminals.  When testing these voltages, hold the black meter lead to the negative terminal of the amp. 

First i'll send an apology for not getting back sooner,workin that a... off. I did as you said and the meter went to zero when checking between the positive terminal and the metal tabs. The meter also went to zero when checking between the negative terminal and the right most legs of the transistors. I'll wait for your response to see where to go next. Have a great holiday and thanks for the help.

There is a chip in the middle of the board, near the transformer, what is the number on that chip?  TL494, TL594, SG3525, SG3524?   I need to know the DC voltage on each pin of the chip.  Be very careful to not touch 2 pins at once, especially 7 and 8, and 10 and 11.  With the chip sitting so you can read the numbers, pin 1 is bottom left, pin 8 is bottom right.  9 is top right, 16 is top left.  If it is a 494 or 594, Pin 8, 11, and 12 should have 12 volts.  

You will have to connected to remote, power, and ground to perform the above.  Black meter lead to the ground terminal of the amp.  Red lead to each pin. 

Ok, The chip is a TL494CN and the voltage measurements are 1=.3, 2=.9, 3=.0, 4=.0, 5=.0, 6=.0, 7=.0, 8=1.1, 9=.5, 10=.5, 11=1.1, 12=2.2, 13=1.4, 14=1.4, 15=1.4, 16=4.5.  

Remove all the fuses from the amp and insert a single 10 amp fuse in one of the slots. using your meter lead, short pin 12 to pin 11 briefly, this should make the amp come on.  We need to figure out why pins 8 and 11 are not getting power.  If this makes the amp turn on, we have verified that lack of power on 8 and 11 is your problem.  Remove power from the amp.  Very important.  With your meter set to ohms, or 20 ohm scale if it is not an autoranging meter, how much resistance is there between pins 8 and 11?  If there is near 0 ohms between them, look for a 100 ohm resistor very near one of the pins.  Brown Black Brown will be the first few bands of the resistor.  Check it to see if it is reading well over 100 ohms.  Also look for a transistor very near labeled on the board as Q1.  If the resistor is ok and you find the transistor, let me know, I will tell you how to check it.   DO NOT remove any part from the board, and do not remove any more clamps from the heat sink yet.  If you read the last post before I deleted it, I thought pins 9 and 10 were 5 volts.  It was not till I read it this morning that I noticed the decimal point.  5V good  (.)5V not so much.

Also look for  a diode very near those components.  Place your meter on the diode test function again and place a lead on each end of the diode, notice the reading, now reverse the leads to the other end and notice the reading again.

I have voltage on the remote lug and the amp powers up when jumper is placed between the remote and 11-12 of the 494.

Camera is on it way. I'll have the picture and get it posted 10 minutes or so.

Sent the pics of the remote lug and ajacent area. The numbers on the transistor UTC, B649A,CREOA. My meter shows O.L on diode test with open leads. Using a Fluke 867B Graphical multimeter.

You can see the trace coming from the remote terminal, it goes to the resistor which goes to ground, and it also goes north under the blue capacitor.  Then it connects to the jumper that is partially covered by the glue of the yellow capacitor, that jumper is positioned east to west.  Can you remove the glue and see where the trace goes from there?

With the numbers of the transistor facing you, one meter lead on the right leg, the other lead on the left leg, notice the reading.  Now move the left lead to the middle leg, notice the reading.  Now reverse the leads and duplicate. 

The trace may go under the board from that point.  We may have to take the amp out of the heatsink.  There are a couple of thengs to watch out for when removing the board.  I will give instructions if we need to take it out.

I doubt I have any endcaps, I do not take them in when I take an amp in for repair.    It appears that the transistor is bad.  Is there an electronics parts store in your area that may sell NTE replacement parts?   If so an NTE 374 is the replacement for that part.  You may be able to change it without removing the amp from the heat sink.  If you decide to take the amp out of the sink let me know. 

You are looking at the side of the transistor with the writing on it when determining left and right?

When i solder in the new transistor,how much concern is there for over-heating the part? I'm not a novice in this dept and can make the connections rather quick,but had questions about how heat sensitive it might be. If it would be worthwhile to have some freeze spray or equivilent on hand. I don't have a de-solder pump,but i'll get one.How well does the solder braid work at wicking it away? I see the stuff everywhere,but never seen it in use.

The braid works OK, you can get a small solder sucker for less than 20 bucks.  Heat on the new transistor is not going to be an issue. 

If you do have to remove the board from the sink, you will have to remove both the front and rear covers, then the 3 screws from the pre-amp daughter board.  Notice the 2 transistor clamps under that board are different from the rest of the clamps.  They need to go back in the same position.  All of the transistors are stuck to the pink tape that insulates them from the heat sink.  You will have to use a pair of pliers on the side of the transistors and rock the parts off of the tape.  You may want to grind any sharp edges off of the pliers.  Try not to penetrate or scratch the tape.  There are several screws that mount the board to the heat sink. 

The RCA and speaker terminal screws are not the same screws.   Keep them separated so they go back in the same places they came from.

The transistor was simple enough to change out,didn't have to remove the board from the heatsink.I checked it afterwards and got the (.)600 you were seeking,and with leads reversed (.)600 again. With 12 v applied it powered up as expected. Is there anything else that should be tested or checked on the bench?

That should be the only failed part.    Connect a speaker to it and see if it plays.  Wherever that is easier to do, on the bench or in the car.

Looks like you've pulled off another long distance repair my friend.All 4 channels of the amp are functioning as designed. I really appreciate your proffesionalism and the time you spent with this. If you'll give me a name and physical address i'd like to at least send you a certificate for a nice dinner,or if you prefer a contribution to this website or possibly a favorite charity,your choice. This site is absolutely the best i've seen for all things 12 volt. Take care.

As you requested,and being one that honors his word,a contribution has been made to this website.I look forward to working with you again. Many thanks.

Most people don't look forward to needing my help again.  You should hope that all of your equipment remains in working order.  However, i will be here if you do need help again.     You left out the word "rather" in your signature line.

You will need to check from one leg to the other 7 and then check from leg 2 to the other 7.  Check all possible combinations and just let me know the highest voltage you come up with. 

The unit may be equipped with a thermal shut off device.  Was there anything mounted to the heat sink other than the FETs and the Diodes?

Not that kind of supply.  This appears to be some new fangled device that has no transformer like we both were thinking.  It appears as though they rectify the 110 and built a DC to DC supply to step it down to 13.8.    I too am suspecting a bad bridge.  He is checking that for his next post. 

i am an idiot wrote:

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This is my first experience with such a device.   Learning as we go.  But I am here till the end. 

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terry osborn wrote:

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I'll take a closer look at it,and i'll take a few pictures and e-mail them to you.Let you know when i've done so. 120v isn't a concern,i work with 4160vac and 600vdc daily.

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He's laughing at 170 volts.

If you PM me your e-mail address or clear your PM box, I can send you the pictures that he sent me.   I have not tried to PM you in a while, but it was always full.  He did send me one pic of the bottom of the board.  I will look. 

Terry, check the DC voltage on the metal tab of the IRF 740s  First black lead on ground and red lead on the tab of each transistor.  Then black lead on tab of transistor on end of row.  Red lead on tab of transistor on the other end of the row. 

I need to look at the chips in the picture and see if I can figure out which one does the job of the 494 in your amp.

Hey I forgot to look and see if I can figure out which chip is used to pulse the DC voltage.  Going to go check that now.

The discoloration on the bottom of the board, what component is connected to the trace that got hot?   When a manufacturer determines that there is a part that is failing more than they expected it to, they mount them in a socket.  I noticed that all  3 of the integrated circuits are mounted in sockets.  That is not going to help us narrow it down. 

With all of the problems that other people are having with the supplies, it is very likely that there are several bad connections on the circuit boards.  You should not be getting different readings, that is definitely not being caused by the surface you have the board sitting on.  You may want to check for broken legs on all heat sink mounted components.  Easiest way is to heat the joint up on the bottom of the board.  The broken legs will move, you will see what I mean if you have a broken one.  Also any where there is a feed through (a trace that ends at a hole in the board.  Then travels through the board and continues on the other side of the board)  You may want to heat them up, remove the solder and solder a wire or leg of a resistor through the hole.

I remember E mailing you a picture with what I thought was a bad solder joint, did you add some solder to it?

I know you didn't tucker out on me.