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Dell M992 Monitor H.O.T. Replacement issue

tick - tick - tick The horizontal output FET was dead shorted. The original is a P9NC60, a TO-220 case deal, which has scant info on the web. The best resolution datasheet I found is 90% illegible:

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No matter: Schematic actually indicates Q504 is a more familiar 2SK2761:

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Side note however: There are some slight differences between the M992 I have and that shown in the schematic; but the horizontal output section seems to be indentical. I got a 2SK2761 and put it in. Power up. The 2nd anode HV came up OK, but not for long: I heard normal dust crackling sounds for about 3 seconds, then no HV, no raster, and the SMPS goes into ticking again. Yes the new 2SK2761 is now dead shorted.

The P9NC60 is a metal tab style TO-220, and it had one of those grey flexible style insulators at the heat sink. The 2SK2761 is a plastic case / tab TO-220, so I used the usual thin layer of heat sink compound and left out the insulator.

The P9NC60 data sheet [ P9NC60.gif ] isn't legible, and I don't know how to evaluate the schematic to determine requirements for a good substitute for the P9NC60. Availability of an actual P9NC60 looks pretty poor (unless I want to order

1000 of them) Are there cases where excessive load downstream results in failure of the horizontal output transistor? A shorted horizontal output transformer? None of the diodes in this area appear to be shorted. Looking for suggestions.
Reply to
Bicycle6228
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Did you check the two drivers Q502 and Q503 and IC501? You'll have to come up with a theory why the first failure occurred, and then, wether that may have taken other components with it.

Regards, H.

Reply to
Heinz Schmitz

I would suspect something in the H-drive took the original HOT out. You should be using a bit more sophistication in your troubleshooting techniques for this circuit.

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Reply to
Meat Plow

This transistor is likely to be made by SGS Thomson and is actually a STP9NC60. If you do a google search for this you will gets many hits and the first one is a downloadable PDF data sheet, and is perfectly readable. Try it ! Ian.

Reply to
Ian French

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