I made the mistake of buying this broken set assuming I could fix it for
resale. Half the raster was missing, so I assumed it was a relatively simple
vertical output problem. Everything else in that area checked good, so I
ordered a replacement vertical IC (TDA8177). These sets are known for cold
solder on the flyback, so I took care of that while I was at it. With the
replacement IC installed, the set powered with a full raster but was bright
white with retrace lines, and kept cycling on and off every few seconds. I
tried lowering the screen controls and powered again, but this time the new
vertical IC failed with a bang and the raster collapsed altogether. What's
more, it blew all three of the little red solid-state fuses by the flyback
(from the voltage surge when the vertical IC blew?). I have one spare IC
left to try - but before I do I want to get some help with this.
I should mention that the previous owner had opened the set up and fiddled
with the screen and focus controls, as well as disconnected and reconnected
the convergence module (he took the module to a shop to look for a
replacement). Too bad he didn't tell me this before I bought the set - if he
had, I would have dropped this set like a hot potato. While the controls are
nothing serious, what worries me are two single wires that connect to the
convergence board - a red one which goes to the screen controls, and a blank
one which goes to the deflection board. The two can easily be reversed by
mistake, with unknown and perhaps damaging results. The two connectors, on
the convergence board, are marked BL670 and BL680 - the red wire is
currently plugged into BL680.
Some advice would be greatly appreciated - if this blows the other IC, the
set goes to the trash and I take another loss I can't afford. Maybe someone
with a service manual can tell me if those two connectors are in the right
places.