robb ha escrito:
Hello,

My old (1994 mfg) 21" DEC digital monitor was screaming/whistling when i
went to log on this morning not loud but annoying high pitch about
frquency/pitch ? of whistling through teeth. there were *no* power indicator
lights (eg. amber for low power sleep mode and green for active ). i turned
it off few minutes turned it on and same whistle immediately with no flash
flicker from screen or power lights. of course immediatelt turned it off

possible short in the horizontal output - I have seen whistling
monitors with this. could be a problem in the line o/p transformer /
transistor, and the power supply is in protection mode.

if you can solder, i would start by desoldering the line o/p
transistor and connecting a 60-100w bulb across c-e, see if it
lights , to check you have b+.

if you opt for that, leave the unit unplugged a couple of days then :
1. stay away from the mains filter capacitor and power supply
2. dont tamper with the big fat red wire which goes to a rubber cup on
the tube

In my experience, actuall disassembling the unit enougjh to get to the
soldered side of the pcb is the most problematic - compared to TVs
they are a nightmare!

In any case it may be worth a shot before tossing it...who knows you
may learn something.- if it doesn't work out i also recommend
freecycle. people usually have tons of monitors to give away, and you
can save em from the landfill.
-B