Re: DYNEX HV AC POWER SUPPLY 2nd FAIL

here are PICs...

Re: DYNEX DX-40L260A12 TV BACKLIGHTS

The HV inverter power supply (INV40N14B) blew one of the two fuses on 24 Vdc input. The fuse and replaced dual P+N channel MOSFETs are circled in RED on pic. However after replacement the set only worked for about 3 weeks and now the "no backlight" problem has returned. It appears the same 3 MOSFETs are shot. This TV set has only 14 CCFLs and the blown section appears to be underdesigned. The two rightmost transformers drive 4 tubes each with 4 FETS in parallel. The leftmost transformer (smaller than other 3 XFMRs) drives 2 tubes with...

I have replaced 3 paralleled 40V dual P+N channel MOSFETS on the HV power supply board. The board is set up with two fuses on the 24 Vdc input feed. I found one fuse blown and replaced it only to find the 3 MOSFETs damaged (via ohm meter test). The power supply worked well for about 2 weeks and now the problem has repeated. It appears the same 3 MOSFETs are blown again.

The PCB had a few traces that were lifted during the repair process but I was able to add some wire wrap jumpers to get the circuit functional the first time.

The original problem which has returned...

Re: New Members - please post your introductions here

Hi to all the tinkers out there . . . I am also new to the forum. Thanks to topcat and the crew!!

My current repair is the HV section on our CCFL LCD TV. My bench is limited and I am on the 2nd go-around now as the fix that I applied, 3 new 40V dual P+N channel MOSFET, only worked for about two weeks. They did make the video visible again but now appear to be caput again. Working on the PCB was painful as I lifted a few traced and had to fit jumpers. So I am thinking something else must be going on. I am...

Re: New Members - please post your introductions here

Hi to all the tinkers out there . . . I am also new to the forum. Thanks to topcat and the crew!!

My current repair is the HV section on our CCFL LCD TV. My bench is limited and I am on the 2nd go-around now as the fix that I applied, 3 new 40V dual P+N channel MOSFET, only worked for about two weeks. They did make the video visible again but now appear to be caput again. Working on the PCB was painful as I lifted a few traced and had to fit jumpers. So I am thinking something else must be going on. I am hesitant...