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jonah1188 28th August 2012 04:14 AM

Jl audio 500/1 excessive current draw
I am working on a 500/1v1. The issues started with the amp produced no output on it but powered on. So i opened it up and seen the all of the output fets had blown along with two 2n3906 transistors. So I thought easy enough replace these few parts should be good to go. Well did that and then when it got hooked back upto the car it started making popping noise and smoke rolled out. This time the PS fets burned up on it. I took it apart again replaced those and hooked it back up this time no cover just to see what was going on. With in just a few seconds the PS fets started again to smoke and get real hot with no load on it at all. So I figured now there must be something really wrong if no load is on it and all I did was hook up power and ground w/ remote. So i started to take the whole amp apart again at work to see if i could see anything else wrong with it and at the same time jumped on this site to see if anyone else has had this problem or at least something for me to go off of so I could check some common issues. Well I did check and a few of the PS resistors where bad so I replaced those along with all of the PS fets again and I figured I could leave the output fets out just to see if I can get the amp to stay powered on without over heating again well that didn't happened while hooked up at work the green led will turn on for a few secs then slowly go off and then just blink on and off and if I let it do this long enough those PS fets get pretty hot. When I did do it this time i hooked up my current meter to see how much it was drawing at it was only around 2.86 amps then it would drop and go back up again and again. From here I removed the PS fets again and decided to check some of the voltages and also see if I had any square waves signals at all going to the fets and or coming out of the output fet driver. Well as long as amp has no fets in it I seem to get good square waves signals and the amp powers on and stays on with no issues. It only has the over heating when I install the PS fets and when I do that all of my good square waves signals turn into garbage. So from this I thought for sure the amp is working i just must have some transistor bad or something did some more checking it looks like those four transistors for the PS fets can go bad so I replaced those put new PS fets and output fets in along with a new output fet driver IC hoping with all of these common parts that can go bad replaced I had to fix the problem well it didnt change a thing just cycles on and off and starts to get pretty hot. I am at a lost I couldn't really find anyone else on here that had these same issues with also changing all of these parts. If anyone can give me some help I can get more information on the voltages and square waves signal I did get but it will have to wait till i get back to work since they have better equipment then i do at home. Thanks

90scaraudio 28th August 2012 09:53 AM

Did you check the full wave bridge? Just a thought...

jonah1188 28th August 2012 01:12 PM

I did forget to mention not sure if it matter or not but when the PS fets do over heat if you are looking at the front of them tabs facing away from you the fets on the right heat up first and get realy hot and the last fet hardly gets warm.... not sure if this means anything.....

Perry Babin 28th August 2012 02:47 PM

In the future, break the text up into smaller segments. It's VERY difficult to read quickly as it is and that means that you're likely to get delayed replies.

Remove the rectifiers next to the power supply FETs, install the PS FETs and check the drive signal. Do you get a clean square wave?

Do the FETs get hot?

jonah1188 28th August 2012 03:21 PM

Sorry about that I will do that asap thanks for the reply

jonah1188 28th August 2012 03:26 PM

To make clear on the rectifier are you referring to d611 and d612 the board rev is 10

Perry Babin 28th August 2012 03:37 PM


jonah1188 28th August 2012 05:29 PM

Big improvement no over heating and light does stay on but blinks once in awhile but could measure voltages those look good. I get my square waves back on the 4 ps transistors. But I am assuming since that is out no power is going to go to the output side since couldn't find anything there. Thanks

jonah1188 28th August 2012 09:27 PM

I did test the diode array it seems to be fine is there some other parts that can be causing this over heating issue tied to this array?

Perry Babin 28th August 2012 11:26 PM

There are 8 power supply FETs. Did you check the signal on the other 4?

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