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Registered Member #79
Joined: Thu Feb 09 2006, 11:35AM
Location: Arkansas
Posts: 673
Hey guys, what would I have to do to get my TV working again with a MOSFET instead of it's original 800V NPN that no one seems to have? The Horizontal Deflection transistor went out.
Here's the original datasheet: Main Specs are: 800V C-E 8A I(C) 6V E-B 60W
Here are two that I have with me I'm considering replacing it with (both MOSFETs).
At first, I tried an NPN 600V, 5A transistor expecting it to fry instantly, but surprisingly it worked for about a week before the TV died again. It happened the same as last time, the color got horrible, then the screen got smaller then the CRT shut off and the power transformer started clicking. The HDT was shorted E-C. Removing it brought back sound and power.
Is there an easy way to use one of these MOSFETs? If you need scope shots, I'm going to get them right now...
Registered Member #162
Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3140
Of the two the 2SK2847 looks best, but the base drive for the HOT may be unsuitable for driving a MOSFET (min 5.5 V G-E reqd.) AND the Vds(on) is high for both compared to a HOT
Registered Member #30
Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706
There's no easy way to replace it with a MOSFET really. Try getting a HOT from a junked monitor or something. I did some playing around with monitors a while back, and I found the BU208D could replace every kind of TO-3 HOT that I blew up. That may not help you though, as it's a European type.
The "2SD2578" rings a bell, I'll have a look to see if I have any. I'm sure I have a bunch of TO-247 HOTs somewhere.
Registered Member #152
Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384
try the BU2508 (or BU2508DF) instead, since it's cheaper than BU208 and similar (or better) specs. And no, it is not possible to replace the HOT with mosfet, if you don't want to redesign the whole horizontal stage.
Registered Member #79
Joined: Thu Feb 09 2006, 11:35AM
Location: Arkansas
Posts: 673
Thanks, but I got it working awhile ago. I did a little research and that chassis is notorious for a dry solder in the inductor that drives the HOT. The HOT was dead too.
Sorry for leaving you guys hanging, I haven't been able to get to the forum in seems like ages.
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TV Doctoring. Replacing NPN with MOSFET?
