Issues with a Bestech 25" CGA chassis ... clicking sound

damadczar

Well-known member

Donor 2012
Joined
Feb 13, 2007
Messages
1,118
Reaction score
95
Location
Johns Creek, Georgia
Issues with a Bestech 25" CGA chassis ... clicking sound

Hi all.

I've got a UMK3 that plays blind. The monitor chassis is making a clicking sound.
I removed the chassis from the tube, and included some pictures of it below.

How do I go about repairing this? I'm pretty much a n00b for monitor repair unless it's a G07.
I've got decent soldering skills, and I'm not afraid to take parts off and put them back on. I just need some help figuring out what to check and fix. There's no documentation or schematics on this thing.

I'm assuming the HOT is shorted out. Where would the HOT be exactly on this chassis? Any idea.

To test it, is that just a diode check with the RED lead on the outside leg, and the BLACK lead against some other grounded metal? Should get some resistance. If I get none, then it's shorted?

If that is the issue, how can I identify the parts that need replacement?

Thanks,
Steven
 

Attachments

  • photo.jpg
    photo.jpg
    98.3 KB · Views: 15
  • photo (1).jpg
    photo (1).jpg
    95.6 KB · Views: 11
Caps?

Hi all.

I've got a UMK3 that plays blind. The monitor chassis is making a clicking sound.
I removed the chassis from the tube, and included some pictures of it below.

How do I go about repairing this? I'm pretty much a n00b for monitor repair unless it's a G07.
I've got decent soldering skills, and I'm not afraid to take parts off and put them back on. I just need some help figuring out what to check and fix. There's no documentation or schematics on this thing.

I'm assuming the HOT is shorted out. Where would the HOT be exactly on this chassis? Any idea.

To test it, is that just a diode check with the RED lead on the outside leg, and the BLACK lead against some other grounded metal? Should get some resistance. If I get none, then it's shorted?

If that is the issue, how can I identify the parts that need replacement?

Thanks,
Steven

Replace the caps, check for any shorts on the B+ line...
Ground your meter to the heatsink and probe the circuit for a short..
you can start at the HOT the center pin...on heatsink and next to the flyback
whats the ohms to ground read??
If it is zero ohms then remove the HOT and then measure again
the ohms on center pin to ground on the trace,if the ohms is high then check the HOT
out of circuit for a short..a short is zero ohms!!!
You dont need a HOT to check a power supply..
with the hot removed whats the voltage at the center pin of hot
all power supply B+ go to the HOT thru the flyback windings..
to the collector of the HOT which is the center pin.

inspect the fly for cracks.. if no shorts on the B+ line then
just replace the caps!! pull each cap write down the uf and voltage
and part location get your list together then install new caps,then test
chassis again..
 
Back
Top Bottom