I have a WG K4915 medium res monitor I'm trying to fix for a friend. Before we got it it was recapped, and we've checked polarity on all of the caps.
Symptoms --
No picture/No raster, did adjust brightness at flyback
0.5VAC for heater voltage at the neck
B+ measures 123v @ TP91 and at R503, which I believe is correct for this monitor.
After about 20-30 seconds of operation, one of the resistors will get very hot. I can change which one gets hot by changing the h-center jumper. In center position, the resistor that is piggy-backed on a couple others (I believe R394 on the schematic) will eventually start to glow. Moving the jumper will cause a different resistor to overheat (but testing the resistors once they cool down seems to indicate they are not damaged).
Things I've tried --
Checked R416 at the neck, tests good, voltage coming in there is about .7VAC, the .5VAC measurement above is at pins 9/10 on the neckboard.
Checked for yoke shorts
Looked for any continuity problems in the heater circuit
Replaced HOT
Swapped Flyback
Bypassed input protection board
Looked for any continuity problems in horizontal circuit
Looking for ideas or suggestions, thanks!
Symptoms --
No picture/No raster, did adjust brightness at flyback
0.5VAC for heater voltage at the neck
B+ measures 123v @ TP91 and at R503, which I believe is correct for this monitor.
After about 20-30 seconds of operation, one of the resistors will get very hot. I can change which one gets hot by changing the h-center jumper. In center position, the resistor that is piggy-backed on a couple others (I believe R394 on the schematic) will eventually start to glow. Moving the jumper will cause a different resistor to overheat (but testing the resistors once they cool down seems to indicate they are not damaged).
Things I've tried --
Checked R416 at the neck, tests good, voltage coming in there is about .7VAC, the .5VAC measurement above is at pins 9/10 on the neckboard.
Checked for yoke shorts
Looked for any continuity problems in the heater circuit
Replaced HOT
Swapped Flyback
Bypassed input protection board
Looked for any continuity problems in horizontal circuit
Looking for ideas or suggestions, thanks!
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