how can u tell if a monitor needs a isolation Transformer?

Liu Kang

New member
Joined
Apr 8, 2009
Messages
60
Reaction score
0
Location
Morro Bay, California
how can u tell if a monitor needs a isolation Transformer?

how can u tell if a monitor needs a isolation Transformer? cuz i have some acade machines and 2 of them are not working (NBA on NBC and a Neo Geo Mvs 2 slot). i have taken the monitors out and noticed they didnt have a Isolation Transomer in them. and if it doesnt need one is it bad to run with a Isolation Transomer?
 
I can answer one part.

It's never bad to run any monitor with...

It can be bad to run some without...

If I'm in doubt, I check the manual..if I can't find a manual, I come here and pester Mod or Ken.
 
Post a pic of the chassis or the chassis model and someone will let you know if you need one or not. It sounds pretty strange that 2 out of 2 games you have don't have one though. Of the games I have bought all of them have had an iso. My games range from 19"-33" and one of them has a med rez.
 
Post a pic of the chassis or the chassis model and someone will let you know if you need one or not. It sounds pretty strange that 2 out of 2 games you have don't have one though. Of the games I have bought all of them have had an iso. My games range from 19"-33" and one of them has a med rez.

I only have 1 game that came without an ISO (a 4600 in a Crazy Kong cabaret). And I've yet to put one in the cabinet, but I HAVE had to replace the bridge rectifiers twice now.
 
how can u tell if a monitor needs a isolation Transformer? cuz i have some acade machines and 2 of them are not working (NBA on NBC and a Neo Geo Mvs 2 slot). i have taken the monitors out and noticed they didnt have a Isolation Transomer in them. and if it doesnt need one is it bad to run with a Isolation Transomer?

Older style monitors have linear power supplied chassis. These need an isolation transformer. "Modern" monitors use a switched mode power supplied chassis. These do not need an isolation transformer. You can tell a switched mode power supplied chassis by the large transformer soldered to the chassis.

http://homearcade.org/BBBB/mon79.jpg

Note the big yellow/black transformer in the upper right side of the chassis. This is it. It's usually not much smaller than the flyback. And, not to be confused with much smaller transformers that can be found on ANY monitor.

Edward
 
If either side of the A/C input is connected to the metal frame of the monitor then you need an isolation transformer.
This connection generally occurs through the rectifier diodes in the power supply.
The isolation transformer effectively 'lifts' the physical connection to the mains thus isolating the monitor from other equipment connected to the power line and eliminating the 'jolt' you can sometimes get when touching two different pieces of equipment.
However, a missing isolation transformer will not stop your monitor from working. It's a safety implementation.
 
Last edited:
First off i got a little carry away on this post, if its too long tell me and i will revise it:

Thanks Elutz, Thats a good peace of info knowing how to spot if the monitor need a ISO or not. i went down to my garage and out the four non-working monitors i have i could instantly spot which ones needed an ISO and which ones didnt. except for one its a 19" monitor i bought brand new and have never been able to install it with out having a "what i think is" a high voltage wave going through it and the bottom of screen getting cut off. but ill get to that later so here's a run down on the monitors.
Non-Working Monitor 1:
25" Wg-25k7191
This monitor needs an ISO for sure this was the sparker when pluged it into a non ISO cab
It doesnt turn on after that but i have a flyback, capkit, hot coming from bob roberts for this monitor so i hope to have it working soon.
http://i698.photobucket.com/albums/vv344/Liu_Kang_MK1/DSC00565.jpg
Non-Working Monitor 2:
25" NeoTec
this monitor does not need a ISO but when i plug it in the yoke lites up and after about 30 sec the picturs shows up on the screen but its rolling and super blury and no adjustment did any to make it playable but im hoping a cap kit will fix this problem.
http://i698.photobucket.com/albums/vv344/Liu_Kang_MK1/neoteciso.jpg
Non-Working Monitor 3:
25" CMG-2500
This monitor also does not require an ISO, the problem with this one is the screen is green i was told the tube was gone bad a while back for a KLOV member that was about 6 month or so ago but no the monitor wont even power on but the monit is the least of my worrys.
http://i698.photobucket.com/albums/vv344/Liu_Kang_MK1/2500ISo.jpg
http://i698.photobucket.com/albums/vv344/Liu_Kang_MK1/DSC00501.jpg
Non-Working Monitor 4:
19" Visual Displays Model# 1019
Ok this one im not sure of but im leaning more towards no ISO Cuz the monitor will not power on if in is hook up through an ISO. but when i hook i up without an ISO the games pictures will show up like i talked about above with the high voltage wave on the screen and this monitor is brand new so nothing should be wrong with it.
http://i698.photobucket.com/albums/vv344/Liu_Kang_MK1/19iso.jpg
http://i698.photobucket.com/albums/vv344/Liu_Kang_MK1/19iso2.jpg
http://i698.photobucket.com/albums/vv344/Liu_Kang_MK1/DSC00567.jpg

Sorry about writing so much thanks for taking the time to read it and helping me out
 
First off i got a little carry away on this post, if its too long tell me and i will revise it:

Thanks Elutz, Thats a good peace of info knowing how to spot if the monitor need a ISO or not. i went down to my garage and out the four non-working monitors i have i could instantly spot which ones needed an ISO and which ones didnt. except for one its a 19" monitor i bought brand new and have never been able to install it with out having a "what i think is" a high voltage wave going through it and the bottom of screen getting cut off. but ill get to that later so here's a run down on the monitors.
Non-Working Monitor 1:
25" Wg-25k7191
This monitor needs an ISO for sure this was the sparker when pluged it into a non ISO cab
It doesnt turn on after that but i have a flyback, capkit, hot coming from bob roberts for this monitor so i hope to have it working soon.
http://i698.photobucket.com/albums/vv344/Liu_Kang_MK1/DSC00565.jpg
Non-Working Monitor 2:
25" NeoTec
this monitor does not need a ISO but when i plug it in the yoke lites up and after about 30 sec the picturs shows up on the screen but its rolling and super blury and no adjustment did any to make it playable but im hoping a cap kit will fix this problem.
http://i698.photobucket.com/albums/vv344/Liu_Kang_MK1/neoteciso.jpg
Non-Working Monitor 3:
25" CMG-2500
This monitor also does not require an ISO, the problem with this one is the screen is green i was told the tube was gone bad a while back for a KLOV member that was about 6 month or so ago but no the monitor wont even power on but the monit is the least of my worrys.
http://i698.photobucket.com/albums/vv344/Liu_Kang_MK1/2500ISo.jpg
http://i698.photobucket.com/albums/vv344/Liu_Kang_MK1/DSC00501.jpg
Non-Working Monitor 4:
19" Visual Displays Model# 1019
Ok this one im not sure of but im leaning more towards no ISO Cuz the monitor will not power on if in is hook up through an ISO. but when i hook i up without an ISO the games pictures will show up like i talked about above with the high voltage wave on the screen and this monitor is brand new so nothing should be wrong with it.
http://i698.photobucket.com/albums/vv344/Liu_Kang_MK1/19iso.jpg
http://i698.photobucket.com/albums/vv344/Liu_Kang_MK1/19iso2.jpg
http://i698.photobucket.com/albums/vv344/Liu_Kang_MK1/DSC00567.jpg

Sorry about writing so much thanks for taking the time to read it and helping me out

I'm confused about a 19" Visual Displays monitor as well (mine is model #125). The box the chassis came in said "Isolation required" but the chassis looks almost exactly like yours. I'm currently trying to diagnose a wave on it's screen in my Pac-Man cocktail.
 
First off i got a little carry away on this post, if its too long tell me and i will revise it:

Thanks Elutz, Thats a good peace of info knowing how to spot if the monitor need a ISO or not. i went down to my garage and out the four non-working monitors i have i could instantly spot which ones needed an ISO and which ones didnt. except for one its a 19" monitor i bought brand new and have never been able to install it with out having a "what i think is" a high voltage wave going through it and the bottom of screen getting cut off. but ill get to that later so here's a run down on the monitors.
Non-Working Monitor 1:
25" Wg-25k7191
This monitor needs an ISO for sure this was the sparker when pluged it into a non ISO cab
It doesnt turn on after that but i have a flyback, capkit, hot coming from bob roberts for this monitor so i hope to have it working soon.
http://i698.photobucket.com/albums/vv344/Liu_Kang_MK1/DSC00565.jpg
Non-Working Monitor 2:
25" NeoTec
this monitor does not need a ISO but when i plug it in the yoke lites up and after about 30 sec the picturs shows up on the screen but its rolling and super blury and no adjustment did any to make it playable but im hoping a cap kit will fix this problem.
http://i698.photobucket.com/albums/vv344/Liu_Kang_MK1/neoteciso.jpg
Non-Working Monitor 3:
25" CMG-2500
This monitor also does not require an ISO, the problem with this one is the screen is green i was told the tube was gone bad a while back for a KLOV member that was about 6 month or so ago but no the monitor wont even power on but the monit is the least of my worrys.
http://i698.photobucket.com/albums/vv344/Liu_Kang_MK1/2500ISo.jpg
http://i698.photobucket.com/albums/vv344/Liu_Kang_MK1/DSC00501.jpg
Non-Working Monitor 4:
19" Visual Displays Model# 1019
Ok this one im not sure of but im leaning more towards no ISO Cuz the monitor will not power on if in is hook up through an ISO. but when i hook i up without an ISO the games pictures will show up like i talked about above with the high voltage wave on the screen and this monitor is brand new so nothing should be wrong with it.
http://i698.photobucket.com/albums/vv344/Liu_Kang_MK1/19iso.jpg
http://i698.photobucket.com/albums/vv344/Liu_Kang_MK1/19iso2.jpg
http://i698.photobucket.com/albums/vv344/Liu_Kang_MK1/DSC00567.jpg

Sorry about writing so much thanks for taking the time to read it and helping me out

That Visual Display monitor needs an isolation transformer. That small transformer you pointed out looks like it's probably in the horizontal circuit (just guessing...by it's location and size). It is no where near large enough to be the power transformer.

Now, why it works without a isolation transformer....and doesn't with one?...Very strange. Do you have 120VAC output at the isolation transformer?

When in doubt about needing a isolation transformer....just post a (GOOD) picture, and someone will let you know. Some monitors can be instantly killed by running them without an isolation transformer (G-07 comes to mind).

Edward
 
ya i dont get it either, when i test the power going into the ISO its 120-122v and coming out of the ISO its 128-130V so it has more juice coming out of the ISO. i did think that transformer was a little small compared to he other monitor that have one but i thought sence it was a new monitor that why its was so small. so Lukenatme you also have a 19" Visual Displays monitor that is smilair that has the wave problem? and yours powers on through a ISO and still has the Wave? an other thing is the Visual Displays monitor will not turn on unless it is grounded and not hooked up through ISO. but no matter what i do it wont power when hooked up throght the ISO i have tryed it on two different ISO one is brand new that i bought just to make sure the other was not damaged.
 
Last edited:
a i dont get it either, when i test the power going into the ISO its 120-122v and coming out of the ISO its 128-130V

are you sure you tested the voltages correctly? that sounds backwards as i thought it's usually a slightly lower voltage (~115) that comes out of an isolation transfomer, not a higher one.
 
http://i698.photobucket.com/albums/vv344/Liu_Kang_MK1/DSC00583.jpg
i put the meter on AC then put the tips into the connectors these are the reading I get so i think im testing it right i have also tested it with my friends meter who is an electriction so i think the reading is right. I alway wounder about the voltage being higher coming out of the ISO so i took a few pics (sorry there not that good) to help u guy better understand what going on. Im not sure want is the INput and Output Progs on the ISO so i look at this picture on Bob Roberts Site and i shows that the Bottom ones are the Inputs and the tops are the outputs
http://www.therealbobroberts.net/buildit.html
But when hook it up like that i get the 130v reading throght the ISO
http://i698.photobucket.com/albums/vv344/Liu_Kang_MK1/DSC00585.jpg
But when i hook it up the other way i get the 120v so its not jumping it up anymore but there hooked up backwards according to Bob Roberts and he Know his Stuff.
http://i698.photobucket.com/albums/vv344/Liu_Kang_MK1/ISO.jpg
http://i698.photobucket.com/albums/vv344/Liu_Kang_MK1/DSC00589.jpg
i know its hard to see the meter reading but its say 121v, but even with the meter reading 121v through the ISO the Monitor still will not turn on even though the votlage is the same for some reason once it goes through the ISO the monitor will not turn on, no yoke light or High Vlotage sound..nothing???
 
ISO's often decrease available amperage as part of the safety features. Do you have a manual for this monitor? I'd be interested in seeing what info it has...
 
i bought it from this place in So Cal and when they shipped it to me they email the manual but i have lost it sence then. about a week or so i call them and asked them to email it to me again and they said they would but i never got the email. i will call them again tomarrow, can u think of anything else i should ask thoughs guy when i talk to them beside getting the manual?
 
That Powertech ISO is even marked as to what is input and output.
PRI-mary is the input and SEC-ondary is the output.
Secondary (output) is marked TOP, which would be the top two prongs.

What is your AC reading from he ISO while that monitor is connected and powered on ?
Where is the power source going into that ISO ?
 
Back
Top Bottom