SMPS ticking
 

Mitac L1450PD monitor. 3of3 (i fixed one, two to go)

when i switch this one on it makes that ticking noise.
tried to get voltage readings but they keep jumping around.
ive only been able to check for dry solder, cap esr, shorted transistors
and FETS. so far everything seems ok.
removing the HOT and placing a 240v 40w lamp across C/GND make the bulb
flash with the ticking noise.
could someone help narrow down my search to a particular area.
the power supply section uses a UC3842 controller ic, K1507 FET,
CNX82A optocoupler ad K2161 + IRF9620 fets on the secondary side.

check for bad electro caps around the
power supply, open or high resistors or
short zenner diode around power supply.
and check the EHT transistor.

"BigTom" wrote in message ...
Mitac L1450PD monitor. 3of3 (i fixed one, two to go)

when i switch this one on it makes that ticking noise.
tried to get voltage readings but they keep jumping around.
ive only been able to check for dry solder, cap esr, shorted transistors
and FETS. so far everything seems ok.
removing the HOT and placing a 240v 40w lamp across C/GND make the bulb
flash with the ticking noise.
could someone help narrow down my search to a particular area.
the power supply section uses a UC3842 controller ic, K1507 FET,
CNX82A optocoupler ad K2161 + IRF9620 fets on the secondary side.