View Single Post
  #5   Report Post  
Posted to sci.electronics.repair
Michael Kennedy
 
Posts: n/a
Default Inverter Repair... I could use some pointers from the experts.

First off thanks for the detailed reply!

This is a bit vague to me. Are you saying there are two CCFL tubes and the
transformer has a seperate secondary and coupling cap for each lamp, and
that one lamp worked for a while?


Let me try to clear up the vagueness.. It has 2 transformers one on each end
of the pcb and each has a coupling cap. It also has 2 500ma fuses. The fuse
which goes to the non working side keeps blowing. I had both lamps powered
up and working for a short while, but they were a bit dim.(may be ccfl
tubes) Then I shut it off and powered it back on and the fuse blew on the
"bad" side. I havn't been able to get the "bad" side to light again. It just
blows the fuse imedately. I've ohmed from the fuse to the transformer's
output and it is within 6 ohms of the working side.

If only one lamp lights that should tell you the inverter is working but
there is a problem with either the relevent secondary winding (check the DC
resistance matches the other) the continuity of the PCB (it looks very
badly burnt) or the lamp itself. If the two lamps share a secondary winding
then that narrows it down even further. Connect the other lamp to the
'working' output and see if it lights up.


I've cut away all the burnt PCB and soldered the cap directly to the lamp
socket. I tried that and it still is blowing fuses so I guess thats not it.

The transformer might be the problem. It has a resistance of 668 ohms vs 931
ohms on the good one. I'm not sure which is the primary and secondary but
I'm guessing the primary is the one which ohms close to zero. Check my
picture to make sure I'm ohming them in the correct place.
http://mikescomputers.homeip.net/DSC00367.JPG


- Mike