Questions about how monitors work

[novamatt]

I just finished my cap kit, and just wanted to understand a little more about what the parts do.  I've heard a lot about the HOT, I know where it is (and I'm getting ready to replace it based on possible solutions I've read to my monitor's symptoms), but what exactly does it do?  Why does it need to be screwed into the chassis?

Additionally, the big cap on my board (it's a 330uf 400v and it's huge) seems to be leaking, but it's not part of the cap kit.  I found a few of them on Mouser's site, but do I want the radial or snap-in version?

Thanks!

[lilshawn]

I've heard a lot about the HOT, I know where it is (and I'm getting ready to replace it based on possible solutions I've read to my monitor's symptoms), but what exactly does it do?  Why does it need to be screwed into the chassis?

Thanks!

the HOT or "horizontal output transistor" takes care of the tough job of applying the electricity (ultimately a magnetic field) to the coil responsible for deflecting the beam of electrons across the screen. it must accurately be timed to line up with the left edge of the screen and then vary the voltage to cause the beam to begin scanning from left to right... then start on the left again, only this time a single line down from before. this happens (on a standard resolution monitor) 240 times before it hits the bottom of the screen... then does all that all over again 60 times a second.

in total, per second, all the time, the HOT must switch the voltage off and on about 14,400 times a second. or about 15,000 times or 15"k" times... hence where the resolution terms come from (15k 25k 31k etc). All this switching results in lots of wasted electricity dissipated as heat... which is why it's bolted down to a big aluminum plate or heat sink.

Additionally, the big cap on my board (it's a 330uf 400v and it's huge) seems to be leaking, but it's not part of the cap kit.  I found a few of them on Mouser's site, but do I want the radial or snap-in version?

the snap-ins have thicker terminals and larger lead space than a regular radial.  if it has a snap in... and it should, replace it with one. the smaller leads often attached to a standard radial cap may not have as high current carrying capability.

this is a snap cap - note the thick lug terminals


this is a plain old radial cap - note the thin wires

[novamatt]

That makes a lot of sense.  One more question for anyone who has experience with it - if I want to understand these things and be able to repair/reshop most arcade monitors, is it worth spending the $250 (or $350) on Randy Fromm's package?

[lilshawn]

That makes a lot of sense.  One more question for anyone who has experience with it - if I want to understand these things and be able to repair/reshop most arcade monitors, is it worth spending the $250 (or $350) on Randy Fromm's package?

there is lots of people here with lots of knowledge. no one person is all knowing at everything, but we have people who are specialized in their particular field or setup. We have an engineer here who specializes in their Nieman/neotec/pentranic chassis. some folks here specialize in early wells gardner and some here who deal mainly with the new digital monitors and LCD's.

i mean iv'e never learned more about this and that then by doing. if your a reader, perhaps Randy's training kit is the way to go for you.

in your case if the tube is still good (IE has not allot of burn in, or is not weak) AND you plan on keeping it AND/OR buying more machines, then, for the most part, it is worth it to you.  allot of the parts have been replaced with superior equivalents, and should last longer in the long run. but knowing what you can substitute and what you can't comes down to knowledge of the way things work.

so in conclusion, my answer is possibly.