Jacques Carrier wrote:
Hi again from Montreal to all fellow techs !!

This is my third posting about this problem. (last one was 6 months
ago).
Most monitors will power on normally with only 110VAC.
This one refuses to power on unless I apply 122VAC. (I use a variac to
boost the input voltage a little).
I checked all power supply caps with an ESR meter.(no problems)Thanks
again to Bob Parker and his famous ESR meter.
I also checked all power supply resistors for correct values. (no
problems)
All diodes and transistors seem OK around the power supply.
I have the schematic and service manual.

Is there something else I should check ??

Many thanks,

Jacques Carrier

What's the rectified voltage at the filter cap? Ripple?
I've seen one diode go and drop the voltage enough to cause problems.
Low capacitance value can be a problem. Not sure if an ESR measurement
always picks this up.

Had a power supply just the other day. Voltage at the output of the
supply seemed close enough to work on my voltmeter. Turned out that
there was 60 Hz ripple on it that I didn't discover until I looked with
a scope. All the diodes checked good with the ohm meter. The scope
told me which one "had to be bad". When I pulled it, the lead was
loose in the package. Checked fine at low current, but wouldn't
rectify the high current required.
mike

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