Jim Yanik wrote:

....snip...


First,you don't extract the main board to service the PS.(a major PITA)
You can remove the PS shield(cage) and bottom cover and work on it
(unsolder) from the bottom. The problem is most likely to be bad
electrolytics (ESR),shorted rectifier diodes,and/or the pre-reg FET(on a
small heat sink) is probably shorted. The FET should be soldered to the 3-
wire ribbon cable,its Molex connector should have been removed by a field
mod when serviced(at TEK).Other failures could be the power oscillator
transistors(shorted or open,along with their base resistors,or the pre-reg
overvoltage crowbar;a bad 51v zener,open 3 ohm fusible R,or shorted SCR.
A less likely possibility is a bad HV multiplier.


....snip...

Jim,

thanks for your reply.

I've just been trying to remove the PSU cage, but so far I haven't succeeded.
In fact I can't really see how it will lift out as the turned over edges of
the side and back panel will block it. I can see why repairs could be so
expensive as it looks like it can take a lot of time to get to the faulty
board! I've removed all the obvious screws, but something still seems to br
holding the cage back, so I can't even try to manipulate it. I would hate to
have to take off the side and rear metal panel as the rear appears to support
the CRT and I would be scared of damaging it.

On the bottom Q947 and Q946 look as if they have been resoldered (and there is
a strange flux residue). I'm assuming that they get so hot (possibly due to
the fault) that the solder melts.

I've found some of your other posts which describe problems with the 2235 PSU,
so if I can actually get at the parts I feel that there is a possibility (with
help) that I may be able to get it fixed.

If I get it open I will describe anything looking obviously broken.

regards...

--Gary