rockford fosgate BD1500 stopped working

[seankane]

I had a similair problem with an amp and the caps were leaking, and the fluid that leaked out made a dark spot on the board and it was causing traces to arc between each other, where the dark area was.

 

[seankane]

Maybe you have some caps leaking and are shorting out with the fluid on the board????

 

[NauTech]

it really doesnt looks like it is leaking... i see nothing at all that would look like leaking and the caps all looks mint ... the spots i am talking about are underneath the PCB on the solder side... like when an electric spark occurs.. them look like the ones i make when discharging the caps with my headlight.. but way more dark

 

[NauTech]

i will dissolder them to check it out...
I have a function on my DMM to test caps up to 2000uF and they are 1500uF so i guess i will be ok

 

[NauTech]

do you think i could check the circuit without the caps on the board ?
just for testing purposes??

 

[seankane]

That I cannot answer but I misunderstood you I guess. I thought the dark area was around the caps, sorry. Something either touched or became so hot it made a solder bridge and shorted, maybe taking a cap out??

 

[NauTech]

i guess my headlight **** did not work to empty the caps.. i just got one nasty POW using the wick ...
the only thing that worked was the resistor but it still made a spark so i was trying to use something else... i guess the headlight is not good..

 

[seankane]

I use a 25 watt 5 ohm resistor and it works great with minimal spark. Never tried a headlight before.

 

[NauTech]

could the mic4420 you sent me be blown and make the output FETs fully powered ? pulling this huge ammount of power ...
where is Perry right where I am in fire to search on this thing
I guess he as to sleep sometimes

 

[Perry Babin]

I didn't receive any email telling me that there was a reply here.

What's the resistance from the gate to the source of the output FETs? What's the lowest reading you have?

 

[seankane]

Even if the MIC4420CT was blown I have never seen one cause these problems such as you are having, not saying it isnt possible but unlikely. It almost sounds like you have a shorted output(s). Run the test like Perry said alot of times by checking the resistance form gate to source you can tell if a fet is shorted. Especially if you have 1 with a really low number like 1.9, 2.4, etc etc.....

 

[NauTech]

did you had time to check out the zillion posts i made Perry ? lol
maybe it could help you to surround the problem
i have dissoldered the 3 right caps and now i will check the resistance between gate and source on all the outputs
it wont be long

 

[NauTech]

with the DMM set to 2000k ohm they ALL read OPEN

 

[NauTech]

finally its not a capacitor check that i have on my DMM its an AMP check that is in the range of 200u and 2000u...
how can i measure the caps out of the circuit ?

 

[seankane]

I think maybe you should try a different range, they should not read OL

 

[NauTech]

they all read a charge/discharged when testing them with the DMM on 2K scale... none are short or leaking

 

[NauTech]

i dont have anything higher than 2000K (2M) on that DMM
and the other DMM i have is a cheap one with 20M range (walmart crap) and even that one reads open...

 

[seankane]

What do the gate resistors read for the output fets?

 

[seankane]

Maybe the rail caps being out are affecting your readings, if their fine you should re-install them and recheck the gate to source resistance on the output fets. I am sure Perry will chime in to steer you in the right direction soon, he is probably reading your zillion posts.....LOL

 

[NauTech]

gate resistors reads between 25.2 and 25.5 ohm they are all ok
i will reinstall the rail caps since they seem ok

the caps are connected to the output FETs on the drain leg i dont think they will affect reading between gate and source... Perry?