Joined: 14 Aug 2011
|Posted: Sun Aug 14, 2011 1:46 am Post subject: Mitsubishi VS-4503R repair & mystery part
I love challenges, but I need some help...
My tv is a Mitsubishi VS-4503R rear projection crt tv, manufactured in October 1990. Frankly, I'm surprised it has lasted this long without any major repairs given that it had been used for several hours almost every day since new.
This unit was working fine until the picture collapsed horizontally, then the tv shut off immediately after, leaving a burnt smell. I pulled the main pcb to find a blackened 1" (approx.) hole in the pcb, located next to the "side pcc" (pincushion?) transformer, the horizontal linearity coil, and a 7w 560 ohm sand resistor.
I've tested the resistor and it measures around 550 ohms, which seems acceptable. The h-lin coil and the pcc transformer are also intact (other than a small amount of soot) and show no evidence of shorting out. I'm planning to re-construct the circuit path in the damaged area with some copper wire.
I'm going to replace the flyback & h.o.t. since I already have those parts...
I also plan to re-cap the main & signal pcbs. The power supply was re-capped 3 years ago. The convergence chips have been replaced and the convergence board was re-capped about 3 months before this event.
The only part missing is one labeled in the service manual as "L5A4". I cannot find this in the parts list, nor on the schematic, the only reference to this part is a page that has a copy of the foil side of the pcb, and this part is located right where the burned hole is. Going by the "L", I'm assuming this is a coil or inductor. L5A4 is wired in parallel with the horizontal linearity coil, going by the foil traces. Again, just to be clear there is nothing left of this part, just the burned hole. I'm wondering if anything was ever there, if so I'd like to know the value of the coil/inductor so I may replace it and attempt the repair.