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My first thought also was a spark gap but the symbol more closely represents a Gunn diode. I'd guess he meant CRT but that's only a guess. And if it is a CRT monitor, that would lean more towards a spark gap than a Gunn diode as I don't believe anything in there should be running at 10GHz or so...
dollars to donuts it's in the flyback circuit of a CRT monitor. They are sometimes used as a high voltage bleed off...if the voltage gets above a predetermined level set by the size of the gap on the top, it arcs to ground and discharges off the excess voltage in the flyback circuit...
It is not a crack, it is a slit. it is part of the item.
What is CTR?
A CTR is a Certified Total Retard..which would be Me
Its funny because in many monitor forums they did not know what this part was but I thought since I got great help fixing my amp here I'd post here for identification. Those dingbats had me spinning in circles. Finally I did a crash course in CRT's and found my problem must be the vertical IC or its surrounding caps. I replaced the caps and my picture filled the screen again with no distortion on the bottom.
But a few hours later I could see the problem coming back a bit. So I changed the V IC and a cap and it was norm again. Next day it started again--so it seems something is shorting out the vertical section from outside. I replaced the main filter cap(the pic was not the flyvback but the main FC).
Anyway I though the part was a cracked cap--but now I know better
I have also worked in the arcade business for many years, and all those arcade games have video monitors runnning 16 hours a day. Big old CRT based monitors. BY FAR most problems are dreid out electrolytic caps. In fact a couple companies sell "Cap Kits" for monitor models. Each is just a collection of the various values used int he circuit. Basically replacing all of them. it solves 90% of the p-roblems.
Look at your board. ANy caps with the plastic cover on the cap shrinking back? Replacce them. You replaced as couple caps in the circuit, replace the rest. Don;t forget that little 1uf/50v one behind the V driver heatsink (or whatever). You may have vertical caps spread around too, not all right together. Watch part number series for example.
And if it takes warming up to show the symptom, get a can of freeze spray and selectively cool areas to look for a sensitive part. If you freeze a part and the picture snaps back to normal, there you go.
Education is what you're left with after you have forgotten what you have learned.
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