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Makvision 29" (27") tri-mode arcade monitor - Fuse blows on replacement
grantspain:
yes DB1 and Q1
q36 is the HOT, when that fails chassis goes into ocp
PTC is the component for the degauss, its marked on the schem
immediately blowing a fuse is a dead short
disconnect ac power input connector when you read the bridge
cruppel:
MOSFET and all 4 bridge diodes are passing the diode check (0.45V ~). I'm not sure how to test PTCs, but when I checked the three pins they all showed as shorted. This was all done in circuit with the ac cord detached.
Edit: ooh my Q36 base to emitter is not showing voltage drop. That must be it. When the HOT goes, are their other things I should check or just replace that?
Edit #2: Hmm now Im reading that its difficult to test HOTs with a digital MM....
grantspain:
hot won't blow fuse on this chassis, only a dead short on the primary psu will do that- anything after primary will put the chassis into ocp
cruppel:
Ahh I see.
How do I test the PTC? Any other thoughts on how I should progress? I really appreciate your help.
grantspain:
prove ptc by desoldering from circuit