Sharp TV Model(Chassis) CJ27D30 Manufactured July 1997
TV came into the shop with a blown fuse and shorted HOT. After doing
some tests, and some soldering, I decided to replace the HOT & fuse. TV
worked fine for three days. Then suddenly, on day four, after being on
for about a half hour, the TV lost picture & sound. A blue screen
appeared, then faded to white. I tried connecting A/V connections. No
change. Then the HOT shorted and blew the fuse.
Before doing anything more with the set I thought that maybe somebody on
this group may have experienced this problem before and could share his
knowledge, which could save me a lot of time.

Sharp bought a bunch of Zenith picture tubes around that time. I have
seen the Zenith made shorting picture tubes in Sharp 25" sets do the
exact symptom you described. Possibly the 27" tube is shorting,
causing excessive current, and blowing the HOT.

I think maybe you have used a sub standard part... please to convince
the master why i shouldnt think this...?

wrote:
I think maybe you have used a sub standard part... please to convince
the master why i shouldnt think this...?

The only thing that I changed was the HOT and the fuse. The fuse is
certainly not the cause. Before changing the HOT I got a data sheet. I
replaced it with an exact same part with the same specifications.
However I don't think the HOT is the cause of the problem. I think that
the picture tube is shorting causing the blue raster, then putting a
load on the HOT causing it to fail. I've isolated the filament pins on
the tube circuit board and used Mr. Goldwasser's trick of having a
floating cathode circuit (wrap a wire around HV transfo ferrite). If the
short is to the cathode then the TV is fixed. Has been running now for
three days.
(If the master is not convinced about substandard part being used, can
he explain?)

Disconnect the crt board and see if again it draws enough current to blow
another horiz output.then ring the LOPT.
"Arnold Stewart" wrote in message
.. .
wrote:
I think maybe you have used a sub standard part... please to convince
the master why i shouldnt think this...?

The only thing that I changed was the HOT and the fuse. The fuse is
certainly not the cause. Before changing the HOT I got a data sheet. I
replaced it with an exact same part with the same specifications. However
I don't think the HOT is the cause of the problem. I think that the
picture tube is shorting causing the blue raster, then putting a load on
the HOT causing it to fail. I've isolated the filament pins on the tube
circuit board and used Mr. Goldwasser's trick of having a floating cathode
circuit (wrap a wire around HV transfo ferrite). If the short is to the
cathode then the TV is fixed. Has been running now for three days.
(If the master is not convinced about substandard part being used, can he
explain?)