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kx 800.4 issues


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jayson33 
Copper - Posts: 165
Copper spacespace
Joined: June 12, 2008
Location: Indiana, United States
Posted: February 28, 2009 at 3:35 AM / IP Logged  

have issues with a kicker kx 800.4 amp keeps going into protection mode the amp is bridged running 2 10" cerwin vegas 4 ohms svc rms 1200watts. Amp was working fine for 3 months. I unhooked subs turn on head unit still goes in to protect mode. checked my ground my meter its good. I have 4 ga power & ground. I hooked the vegas to the other amp KX 600.2 the worked fine the amp did not go in to protect mode. The KX 600 is working fine no issues. The gains on the 800 set less than 1/4 of the way up. So thats the problem I have any

help would be great ( yes I know there kickers that could be the issue, Told my son should have got Memphis

My wife thinks bagging a truck means you kick it in the truck nuts
i am an idiot 
Platinum - Posts: 13,579
Platinum spaceThis member consistently provides reliable informationspace
Joined: September 21, 2006
Location: Louisiana, United States
Posted: February 28, 2009 at 6:39 AM / IP Logged  

The amp has shorted output transistors.   It is a very simple repair if you have even basic soldering skills.  Let me know if you are going to attempt the repair, I can walk you through it.

This is a picture of the 650.4, for all practical purposes it is the same as your amp.  http://ampguts.realmofexcursion.com/Kicker_KX650.4/inside1.jpg  The area to the left of the picture is the power supply section.  To the right of the yellow capacitors are the output transistors.  You can easily get to 2 channels of the amp, the other 2 channels are located below the preamp board.  To remove the preamp board there are 3 machine screws that go through that board.  Remove them and put separate of the other screws.  Then remove the 4 screws that secure the endcap to the heat sink, then remove the screws from the RCA jacks.  Remove the end cap and lift the preamp board straight up.  Now you can get to all 4 channels of the amp.  Using a meter set to the diode test function, place the black meter lead to the center leg of one of the outputs, now the red lead to the rightmost leg of the same output transistor.  Notice the reading, repeat for the other 7 output transistors.  One or 2 of them will read significantly lower than the others.  Before you remove the clamps off of the transistors, notice the difference of the 2 clamps under the preamp board.  Make sure you put those clamps back in the same place and in the same manner they came out.   If you find the shorted ones, they need to be replaced.  If only one is shorted, I would still reccommend replacing both on that channel.  I do not remember if they are TIP35C and TIP36Cs  or  2SB688 and 2SD718s.  Either should be easy enough to locate.  Do not attempt to remove the board from the heat sink without further instructions.  Let me know what you find out.

jayson33 
Copper - Posts: 165
Copper spacespace
Joined: June 12, 2008
Location: Indiana, United States
Posted: February 28, 2009 at 12:57 PM / IP Logged  
Thanks for the info I will open it up and check them all out. I think I will try to do this repair I do have some basic understanding of electronics. And would gladly accept any Info you can give. What would be the best brand of componits to use? I will let you know the results from the testing. Thanks for you time
My wife thinks bagging a truck means you kick it in the truck nuts
i am an idiot 
Platinum - Posts: 13,579
Platinum spaceThis member consistently provides reliable informationspace
Joined: September 21, 2006
Location: Louisiana, United States
Posted: February 28, 2009 at 5:36 PM / IP Logged  

What are the numbers on the transistors?   If they are TIP35 and 36 I would look into Motorola brand.  Available at digikey.com or mouser.com.  The 2SB688 and 2SD718 are available at MCM Electronics.  They do have a website you will have to search for it.  1-800-543-4330 

jayson33 
Copper - Posts: 165
Copper spacespace
Joined: June 12, 2008
Location: Indiana, United States
Posted: February 28, 2009 at 7:03 PM / IP Logged  
They are TIP35C & TIP36C. The first 4 on top left I linked a pic of it are shown on  my meter reading 001-002 all others 660-670 range. So I'm asuming the first 4 are bad?kx 800.4 issues -- posted image.
My wife thinks bagging a truck means you kick it in the truck nuts
i am an idiot 
Platinum - Posts: 13,579
Platinum spaceThis member consistently provides reliable informationspace
Joined: September 21, 2006
Location: Louisiana, United States
Posted: February 28, 2009 at 7:33 PM / IP Logged  

Yes you are correct.  The only pic I had access to was the 650.  It has one each per channel.  Your amp has 2 each 35 and 36 on each channel.  Using your meter you can figure out which of the 2 are shorted by following this procedure.  Black lead on middle leg red lead on the leftmost leg of the same teransistor.  One of the 35s will read lower than the other.  Figure out which one is reading the lowest and cut the legs off of it.   Do the same for the 36s.  Then you can clamp the transistors back down, put a single 10 amp fuse in the amp and power it up and see if it works again.  Do not play it loud at all.  Just make sure it has clean audio and no protect light.  If it is as stated, all you need to do is replace the 2  35s and 2 36s.

The green stuff behind the transistors is a heat conductive tape.  The transistors are probably stuck to the heat sink with that tape.  The safest way to get them up is to take a pair of pliers and grab the transistor on the sides and rock it genly off of the heat sink.  Make sure you do not tear the tape.

jayson33 
Copper - Posts: 165
Copper spacespace
Joined: June 12, 2008
Location: Indiana, United States
Posted: February 28, 2009 at 8:07 PM / IP Logged  
O.K. readings from left to right are 015, 004, 000, 011. So I need to remove 2nd & 3rd correct? Do I need to put a 10 amp fuse in all 3 fuse slots? To check the amp. I have a mouser catalog & the motorola is the better replacement. If it checks out I need to replace the two I removed or should I replace all 4 of them
My wife thinks bagging a truck means you kick it in the truck nuts
i am an idiot 
Platinum - Posts: 13,579
Platinum spaceThis member consistently provides reliable informationspace
Joined: September 21, 2006
Location: Louisiana, United States
Posted: February 28, 2009 at 9:26 PM / IP Logged  
Yes the 2 middle ones appear to be the shorted ones.  You need to replace all 4.  They all 4 went through the same situation, the 2 that are not shorted are probably weak.  Only one 10 amp fuse, the other slots need to be empty.    The reason for the 10 amp fuse is incase there is a problem, you will not take the power supply out.  The amp will play after you remove the shorted ones but you do not need to play it for any extended time.  This is just to let you know if more troubleshooting is neccessary.
jayson33 
Copper - Posts: 165
Copper spacespace
Joined: June 12, 2008
Location: Indiana, United States
Posted: March 01, 2009 at 12:36 PM / IP Logged  
I hooked up amp got green light but when I turned head unit on the protect light flashed slowly. What does that mean if anything? It did not blow the 10 amp fuse or anything. But when head unit was shut off agin the protect light went out.
My wife thinks bagging a truck means you kick it in the truck nuts
i am an idiot 
Platinum - Posts: 13,579
Platinum spaceThis member consistently provides reliable informationspace
Joined: September 21, 2006
Location: Louisiana, United States
Posted: March 01, 2009 at 12:46 PM / IP Logged  
Hve you checked your speakers?  Try it again with only power ground remote and RCA cables.  If the protect light does not flash, you could have a problem with your speaker.  That may be what took the amp out.
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