" snipped-for-privacy@yahoo.com" bravely wrote to "All" (13 Sep 05 08:17:41) --- on the heady topic of "19" KDS monitor model:XF-9P,chassis:C812"
si> From: snipped-for-privacy@yahoo.com si> Xref: core-easynews sci.electronics.repair:342035
si> 19" KDS computer monitor (flat si> screen),model:XF-9P,chassis:C812,year:Feb 2002,LG Electronics si> (Goldstar) CRT,UL Listed:7K04 (Sampo).Problem no power I found si> Q706=3d2SC5584=3dNTE2533=3dSMPS x-fmr transistor is shorted due to cracked si> solder connections at the base signal drive components:
si> R723 si> D705 si> R734 si> D706 si> R720 si> R721 si> T701=3dhorizontal driver x-fmr
si> I replaced Q706 the monitor powered up with hv for a second then a si> chirping with an increasing rate from the power supply so I now si> D706=3dBY459F (diode connected to collector and emitter of Q706) is si> shorted but the new Q706 is fine. si> I would like any common repair tips for this chassis before I replace si> D706 and I would like a possible NTE substitute as NTE does not list si> one and this diode comes in a rectangular case that is screwed on same si> chassis heatsink as the SMPS x-fmr transistor (Q802=3d2SC5339).
si> I don't repair computer monitors because usually about 70% of them si> have defective flybacks but I rang this one and it's fine.Thanks in si> advance. Note:this unit is similar to 19" HP computer monitor M90 si> model:D6433A,chassis:C812
si> Sidney si> Dartmouth,Nova Scotia si> Canada
When the hot and damper want to self destruct it is a sign the fbk pulse is likely peaky. This may be caused by an open in the peak control network, often just a resistor with a high voltage disk cap. Check the base drive to the hot has the proper waveshape. Check derived supples for shorts, i.e. vertical, etc. No specific tips for this model but they are pretty much the same. Why are you fixing it?
A*s*i*m*o*v
... "Bother!" said Pooh, as he saw the sparks and smelled the smoke.