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Sharp TV - Blue Screen - Blows HOT

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.

Reply to
Arnold Stewart
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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.

Reply to
dkuhajda

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

Reply to
jwhmca

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?)

Reply to
Arnold Stewart

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