Monitor power questions

[Nipedley]

While my main monitor was out, I figured I would try and re-route the connection to my top monitor - however, I get no signal. This has happened before, and I fixed it by re-connecting the main monitor to the same power supply (isolation transformer) as the top monitor - is the top monitor not displaying video, because its being given overvoltage? (The power wires for the two are shared, so is it possible that by being un-connected the top monitor is getting too much?) Second question, if I disconnect the top monitor too would anything happen to the isolation transformer? Seeing as how the voltage is being put in, but not going anywhere else.. I'd like to test some of my games, but not too happy with leaving a malfunctioning monitor online. Thanks

[Nipedley]

Bumpety bump.. please if you know tell me, I need to test out some of my games..

[Ken Layton]

What machine is this?

[Nipedley]

Sega Megatech.. two monitors, both powered from the same cable from the isolation transformer. Not a wiring hack job, that's the original wiring for the monitor power (I have another harness to compare it to).

I do have another isolation transformer (the spare) that I have pulled that I could use to power the top monitor, but I'm worried about leaving the main isolation transformer with no monitors attatched and also that I hear isolation transformers can kick up a storm if they're arent screwed down properly (which mine wouldn't be at all)

[grantspain]

What monitors you got in your megatech,are you in uk or US.I worked on hundreds of megatechs in the 90s in the UK,all had about 24inch bottom monitor with a 10inch top for the game menu and credit.All of these were hanterax 9000 which had 4 wires as the power input 1 pair 240v degauss 1 pair 110v monitor supply until i know your type monitor cant give any more advise.But i certainly cant see a problem with leaving a monitor disconnected from the transformer,if the power aint going nowhere it aint going nowhere(if you know what i mean) as long as the wires are insulated and not shorting.

[Nipedley]

yeah they're both hantarex mtc 9000's, a 19" and a 10", and I'm in the UK 

[grantspain]

Where in the uk are you?how much knowledge do you have on monitors?if your confident i might be able to give you some repair advice as the hanterax 9000 chassis had common faults.Please post back starting at the beginning explain what you have done so far,because some of your first post did not make any sense and i need to know exactly where to start.

[Nipedley]

Well the machine was a wreck, I've fixed everything but the two monitors and one of them partially - I'm assuming that it needs a cap kit, as it works fine apart from screen rolling when both monitors are wired up. I did a partial cap kit on one of the monitors which fixed a lot of problems I had, but going to do a full one soon.
Apart from screen rolling, the only other issues is that the 19" monitor has had its degaussing coil cut - though I tested and its not shorted out.

[grantspain]

when you connect both monitors one rolls,which one(top i bet)?
will your monitor adjust against the roll on the adjustment card.
if you reconnect your degauss coil after joining the cut wire does it blow the fuse on the chassis,if so its your ptc componant.

[Nipedley]

Sorry, both roll independently, I believe its a capacitor problem on both as I did half of the caps on one and it was tons better - and no, the adjustment doesnt stop the rolling. It'll slow it to a crawl but thats as far as it gets, within 2 minutes it's be back.

ADD: And I said when both are connected, because the top monitor wont even display a picture without the main monitor connected - but if I wire them up to a seperate transformer, they both still roll by themselves

[grantspain]

I dont think the fault is your monitors,its sounds like a sinc fault.I have seen this before,im sure there is a switch on that chassis that changes the sinc,buts its such a long time since i have seen a 9000 i cant remember where it is.i am positive its not a cap fault because its highly unlikely for two monitors to have the same fault at the same time,its got to be your signal in.
has anyone changed any of the wiring on your cab in any way?
do you have any earth wires connected to your monitors?
if you find the sinc switch activate it to the opposite direction then try to readjust.
i am sure your problem is not serious just a pain to find.
i am positive i had this self same problem on a megatech once i am sure it turned out to be something one of the engineers had done,either a sinc wire in the wrong place,something with the earth or that switch for the sinc-i am trying really hard to cast my mind back 15years.
if poss can post some photos of your chassis,wiring to the chassis including power in.
also have you checked your 5volts on the power supply?
i have got a feeling this is something to do with that sinc switch.

[Nipedley]

I dont think the fault is your monitors,its sounds like a sinc fault.I have seen this before,im sure there is a switch on that chassis that changes the sinc,buts its such a long time since i have seen a 9000 i cant remember where it is.i am positive its not a cap fault because its highly unlikely for two monitors to have the same fault at the same time,its got to be your signal in.
has anyone changed any of the wiring on your cab in any way?
do you have any earth wires connected to your monitors?
if you find the sinc switch activate it to the opposite direction then try to readjust.
i am sure your problem is not serious just a pain to find.
i am positive i had this self same problem on a megatech once i am sure it turned out to be something one of the engineers had done,either a sinc wire in the wrong place,something with the earth or that switch for the sinc-i am trying really hard to cast my mind back 15years.
if poss can post some photos of your chassis,wiring to the chassis including power in.
also have you checked your 5volts on the power supply?
i have got a feeling this is something to do with that sinc switch.

I had the same ideas initially, unfortunately this is a project I've been working on since last April! I've tried nearly everything to do with wiring, and I have several original intact video harnesses too.. tried the sync switch, and it's set to the correct position. The 19" has the earth wire connected, though the 10" does not. I also checked all of the voltages from the power supply and have tried 3 megatech boards and one jamma board with the same results. I dont know what else there is to check or than capacitors hehe. I really appreciate the help, I can imagine what it must be like trying to remember that far back. I have trouble remembering yesterday

[grantspain]

I am sure i had exactly the same fault on a megatech,if you disconect one of the monitor sigals its works fine correct?
I remember it turned out to be something really obscure.
I do remember there was something strange about the wiring in these cabs either the supply to the monitor or the sigal cable.
its sound like when both monitors are on there is not enough signal for the sinc or there is interference.
the ideal situation would be to get a signal from another machine onto the top monitor this would prove whether the fault lies on the power or signal side of things,i have a signal generator so i would hook that up.If you have another psu,jamma board,jamma connector build a test rig it would not take long to do-if the fault remained it would be something to do with the power wiring or the monitor.
It is a particularly a sod of a fault you have.
I understand what you saying about the caps on the monitors and it will do no harm replacing them as you can get them at maplins for pennies,wish i was in the uk i would come have look for you,please keep me posted whats happening.
one last thought-you have two sinc signal wires on your wiring harness one horizontal,one vertical-try disconnecting one at time see  if you have a change in the lock-then reconnect starting with the last you disconnected.

[Nipedley]

I am sure i had exactly the same fault on a megatech,if you disconect one of the monitor sigals its works fine correct?
I remember it turned out to be something really obscure.
I do remember there was something strange about the wiring in these cabs either the supply to the monitor or the sigal cable.
its sound like when both monitors are on there is not enough signal for the sinc or there is interference.
the ideal situation would be to get a signal from another machine onto the top monitor this would prove whether the fault lies on the power or signal side of things,i have a signal generator so i would hook that up.If you have another psu,jamma board,jamma connector build a test rig it would not take long to do-if the fault remained it would be something to do with the power wiring or the monitor.
It is a particularly a sod of a fault you have.
I understand what you saying about the caps on the monitors and it will do no harm replacing them as you can get them at maplins for pennies,wish i was in the uk i would come have look for you,please keep me posted whats happening.
one last thought-you have two sinc signal wires on your wiring harness one horizontal,one vertical-try disconnecting one at time see