Hey guys, i thought i would start by attempting to fix the jl 300/4 but that might be too advanced for me right now. I figured id start with something that is less complicated. I had a directed d800 that was popping the amp fuses, not the inline ones. So i took the amp apart and noticed there was a irfz48n that was shorted out (see pic) Anyway i replaced all 4 of them, and i powered the amp on it worked for a few minutes but i noticed the ground wire was getting really hot. So i took it off checked everything out, everything looked ok. But then when i hooked the amp back up it kept popping the inline fuses not the amps fuses. Any ideas ?
Thanks
-Rob
Thanks
-Rob
Last edited:
Remove the rectifiers. Does the amp blow the fuse (15 amp fuse suggested below).
Insert a 15 amp fuse in the B+ line and clamp all remaining components tightly to the heatsink before applying power.
Insert a 15 amp fuse in the B+ line and clamp all remaining components tightly to the heatsink before applying power.
The Z48s are the power supply FETs. The rectifiers are near the large capacitors (possibly fully encapsulated -- difficult to see in the photo).
The heatsink is the large aluminum outer shell. The missing parts in the photo are clamps.
The heatsink is the large aluminum outer shell. The missing parts in the photo are clamps.
ok, so after removing the rectifiers, the inline fuse doesnt blow, but it puts my regulated powersupply into protect.
14v 10 amp constant 12a surge.
i have a 12-15v adjustable power supply regulator that surges at 52 amps that will be here tommorow.
i have a 12-15v adjustable power supply regulator that surges at 52 amps that will be here tommorow.
There's very likely a problem if it trips the protection in the 10 amp supply.
Remove the 4 power supply FETs and measure the DC voltage on the gate pads for all 4 of the power supply FETs.
Remove the 4 power supply FETs and measure the DC voltage on the gate pads for all 4 of the power supply FETs.
Q11 5.05 / 13.8 / 0
Q12 5.05 / 13.8 / 0
Q13 5.05 / 13.8 / 0
Q14 5.05 / 13.8 / 0
Thats what i measured at the gate pads.
Q12 5.05 / 13.8 / 0
Q13 5.05 / 13.8 / 0
Q14 5.05 / 13.8 / 0
Thats what i measured at the gate pads.
Is it possible that you had a solder bridge on any of the power supply FETs?
Did it shut down the 12v power supply before remote voltage was applied?
Did it shut down the 12v power supply before remote voltage was applied?
There could have been a bridge, i cleaned up all the contacts on the bottom. If there was a short are all those fets dead most likely? i also noticed that on the bottom of the board near the amp fuses there was some corrosion, so i cleaned all that off too.
You may try putting some sort of a current limiter on the B+ power cable. I use a 100 watt 2 ohm resistor...Be carefull unless you like buying more parts..
So heres a small update, i replaced all the powersupply fets, and put the rectifiers back in. Amp turns on, protection light comes on for a sec then shuts off (not sure if thats normal) Amp stays on and doesnt blow fuses anymore. But now there are other issues i have no audio output.
- Status
- Not open for further replies.