Kortek 2914f advice please! My word, am I ever lost-

[bobbyb13]

Aloha kakou!

After a long time looking, last month I finally stumbled onto a real arcade monitor for my WIP cabinet.

CRTs are nearly extinct out here (apart from a lot of Sony Trinitrons that is- of which I own 4 now- including a 36" one.  If anyone wants to come visit and teach me how to RGB mod these things you have free room and board and complimentary surf lessons for as long as you want!) so I truly was ecstatic to find a REAL arcade monitor for my new monster out here-

Until I smelled the secondary windings on the isolation transformer melting after my third ArcadeVGA trial/setup run (maybe an hour and a half run time)-

And it started the dreaded clipping out click-cycle before I could power it down.

I followed the schematic from the real bob roberts site for building out the power supply side of everything for the cab too (and I'm an electrician in my adult life- so I don't think I messed THAT up)-

But, have I screwed up something that fried my (not mine for long obviously) beloved (albeit used of course) monitor that I only got to run for a few hours?!?  (I DID get to play Ms. Pac-Man, Galaga and Stargate a few times though    and didn't they ever look awesome!!)

I got a new isolation transformer (not sure this monitor even needs one, but can't hurt, right?  Or CAN it?!) but it seems folly to think something isn't cooked on this chassis- and I won't just try again to see and make it even worse.

I have to assume that it needs capacitor replacements anyway and would love to use this opportunity to learn monitor repair also, HOWEVER, apart from having as much free time as the proverbial one-legged man in the (ahem!) kicking contest, I would rather send the chassis to someone who can fix it properly rather than risk destroying what may be my only chance to own a real arcade multisync out here.

So, for anyone who would know and have time to answer...

1.) Could maybe just the isolation transformer have been bad? (or was using one to begin with bad?!)
2.) Would having the isolation transformer mounting plate being grounded potentially be a problem? It is in my real Rush 2049 cab so I figured that was the way to go, so it was in the MAME cab too.
3.) Does anyone know if, say, a Windows screen saver being enabled (and the screen resolution switching element of that cycling?) could contribute to frying things?
4.) Is there a recommendation for who best I should send this to for repair (especially in the interest of longevity- price be damned?)  I tried contacting someone I believe to be reliable but with no judgement passed, lack of a reply has given me pause.

I have read through the manual I found for this monitor and it may as well have been written in Korean (ha!) since I know nothing of this arcane art, and all probably meaningful info I found there, here and elsewhere falls into the same category sadly.

Any wisdom is greatly appreciated because after weeks of searching the forums and the internet I am still really lost.

Mahalo nui loa!
Bobby

[lilshawn]

the KT-XX14 series monitors are a modern quad resolution monitor Standard/medium/VGA/SVGA monitor.

manual here: https://na.suzohapp.com/service_center/pdf/ktxx14x_sm.pdf

1: your isolation transformer was made bad by improper load. "switchmode" power supply monitors don't need isolation transformers. all it would do in this case is limit the amount of current available to run the monitor (and then burn out due to way too much current trying to be pulled through it) which is what's happened here. older style "regulated" power supplies must be isolated from mains because they are not neutral referenced to ground and would pose an electrocution hazard as well as fry themselves if connected directly to mains. (hence why they need an isolation transformer.)

2: probably not. doesn't really matter except in a failure condition. so maybe. not a big deal either way. in any case you don't need one.

3: no. constant resolution switching???....debatable. some say it's made to take it...other say not. I personally don't think so. trying to force a weird resolution can damage a monitor.

4: run it without the isolation transformer first. your transformer is limiting the amount of current available to the monitor that it needs to run.

[bobbyb13]

Lilshawn, thank you IMMENSELY for taking the time to read and answer.

All the other parts of this hobby have been really fun actually but monitors still freak me out.
I will take a shot at running it minus the transformer and hope I didn't roast anything by being a neurotic noob.

I will let you know how I do!

Mahalo nui loa,
Bobby

[lilshawn]

if it's still ticking connected directly... it's entirely possible that the horizontal output transistor has been killed.

if a switch mode supply (SMPS) detects an overload condition, (like a short on it's output or extra high load) it will shut down and attempt to restart. this is what makes ticking/tweeting/chirping/clicking noises. the tick can vary from once or twice a second...sounding like a tick to several hundred per second...sounding like a tweet.... depending on the manufacturer of the components used in the power supply and how it's designed.

[bobbyb13]

Thanks again for the reply lilshawn, truly appreciate the wisdom.
I am almost entirely monitor ignorant still.

I finally had a chance to try putting this back together and in my WIP cab and powering it up-

and now I can't find the pictures I (thought) I took of the ground wire connections before I pulled the chassis out of the frame.

Pictures of the yoke and neck board harnesses I found, the 3 ground wires- nope.  Lots of searching the interwebs hasn't yielded fruit either.

I have found 3 unused terminals- one on the main board and 2 next to each other on the neck board- but I imagine it is important which wire grounds where if those happen to be the spots these wires go.

Perhaps I should try a new thread to see if I can find someone with one of these monitors to chime in!

[lilshawn]

they are usually pretty obvious... quite often printed on the boards themselves is "GND" for ground. generally if it fits or reaches the spot... it's where it goes... if you have to stretch the wire or undo it from a bundle or something to get it where you are looking to plug it in... it's not where it goes. the neckboard can have a singe or double connection for ground. usually this is connected to the tube with the bare braiding wrapping around the outside of the tube..springs holding it in place.

while not a be all to end all guide, if you look at the solder side of the board, these ground spots typically have great big traces running around the outside of the board... sometimes connected to screws and stuff... and into big ares inside the board. if it's just got a dinky little trace, it could be a test point.

if you are just looking for a spot to ground to, any metal on the frame will do in a pinch. all of that should be grounded to dissipate static.

just be sure you plug the degauss coil (big black coil running around the outside of the tube wrapped up in tape... it typically has blue wires but could just be black) into the proper spot. sometimes companies will make a double ground wire with a plug that has the same spacing as the degauss plug that will plug onto the connector... and you end up blowing your fuse/circuitbreaker cause it's connected directly to mains and now shorted together.

[bobbyb13]

I got it!
Apparently I didn't destroy anything (at least in the short term) with the isolation transformer previously.

I was using the logic of 'does it reach' and 'does it make sense' to land those ground lines and- success.

When I looked at the schematic (which still makes my head spin from not knowing what is going on there) I did notice that the ground from the AC in line encircles the whole layout just as you said.
I was just hoping to avoid dead shorting something and roasting stuff I do not yet understand.

I'll have to look up nomenclature for boards and their schematics to see if I can learn a bit more if I can find the time.

Again, thank you immensely for your replies.

This thing looks unbelievable and to have a real monitor in this cab will be awesome.

Bobby

[lilshawn]

 

no worries, this whole forum is here to help each other out. not everyone knows everything....but there is enough of us that know enough about certain things we all have it covered.

some of those schematics can be pretty terrible. once you've stared at them enough it just becomes second nature.