Monitors keep blowing fuses...on 2 machines!

[allroy1975]

Hopefully I can get some Ken Layton action on this issue...    I'm finally biting the bullet and I'm gonna try to learn a bit about monitors...so bear with me here.

Let's start with machine #1.  it's a cocktail and has a VideoMaster13 (?) monitor in it.  at least that's what the chassis says.  I also have a System I cabinet.  I'm trying to get this thing running off a PC.  the native System I monitor kept rolling on me so I pulled this Video Master13 and gave it a shot in the System I -  it worked great.  I put the old monitor and put it back in.  I like the game in the System I so it won't be mamed anyway. I put the VM13 back in the cocktail last night, fired it up and it seemed to make a bright blue light for about a half a second and then went dead.  the rest of the cabinet (at least the fan at the bottom) seems powered...

I looked around on the Chassis (that is like..the big circuit board of a montor, right) and it looks like I blew a fuse there.  replacing the fuse shouldn't be a HUGE deal, however I'd rather it didn't happen again.

Oddly enough I am having the same issue on that System I cab with the montior thats in there.  I beleive the monitor in that one to be a  Electrohome GO7. 

It seems to be a power supply problem to me...but like I said....this is my first time REALLY digging into monitors...

Anyone feel like helping a monitor newb out?  Please?

Thanks in advance.

Allroy

[grantspain]

if the fuse is blowing black then you will have a dead short on the primary ac psu circuit-this usually caused by a diode short on the bridge rectifier circuit,a short degauss coil or the degauss ptc component-if the fuse just blows normally then you could be looking at a faulty cap,transistor further in the circuit i.e the horizontal output transistor.but normally any faults in the circuit after the primary ac cause the monitor just to go into trip not blow the fuse
also just check you did not trap any wires or have any metallic objects drop onto the chassis whilst swapping

[Kevin Mullins]

Were they doing this before the swap ?

[Ken Layton]

Both these monitors require an isolation transformer.

[allroy1975]

Both these monitors require an isolation transformer.

Okay, I haven't dug into them much, but I do know they have Isolation Transformers...and they were both working  The cocktail cab is jamma and doesn't have anything hooked up to it, but the monitors at least powered up and glowed.

I never even considerd all the stuff that COULD go wrong with these things..just figured it had to be something simple somewhere..didn't think about a short or anything.  I'm beat right now, but I'm gonna go down and dig into the cocktail one tomorrow night.  Do I need to worry about being killed by anything as long as I stay away from the tube?

Thanks a LOT for replying guys.  BTW the priority one (cocktail) doesn't seem to be blowing black.

[grantspain]

just dont stick your fingers in the anode cap with the monitor switched on unless you want to end up looking like me,yeah maybe worth just hooking out the whole monitor perhaps you have just a bad solder joint somewhere

[allroy1975]

Okay....well.....crap.  Nothing makes people wanna help a guy like misinformation.

I took pictures of the fuse and a bunch of other stuff and was getting ready to shrink them down to postable size...and I noticed...hey!  that fuse isn't blown!  so I got out the multimeter and sure enough, it tests good.  So.not sure if that's good or bad.

So..now I've got that symptom (what happened) and no blown fuse.  any other guesses?  this seems like a really nice monitor.  or at least easy to use.  I started to move remove the chassis but then thought better of me messing with that stupid cap and all that's attached to it on the chassis.  So I've taken some pics and hopefully you guys can help me out.

I've googled everything I can think on the chassis to try to find a flow chart or manual or SOMETHING.  but I've come up empty.   

Here are some other pics I took of things I think are probably relevant.

thanks a lot guys.

First pic is the board, next are the places I assume the power is coming from.  I traced the wire from the power and it seems to go to both of these?

[grantspain]

is your input voltage present?

[allroy1975]

what do you mean by present?  There?  are you asking me to mesaure it?  I think I can do that. 

IF that's what you're asking.....   

[grantspain]

sorry english english(the proper version),yes is your mains input voltage there,you know coming into the chassis,on the plug,present

[allroy1975]

okay, since I'm new to all this, I'll have to do my best at figuring out what kinda current and how much should be coming through there. 

I mentioned I was a monitor newb right?

[grantspain]

set your meter to a/c input,the black lead in common and red lead in voltage a/c d/c,then put the probes on each of the two input a/c lines hopefully it will say 110v or thereabouts(remember i'm english and we have 240v to contend with-big shocks)

[allroy1975]

set your meter to a/c input,the black lead in common and red lead in voltage a/c d/c,then put the probes on each of the two input a/c lines hopefully it will say 110v or thereabouts(remember i'm english and we have 240v to contend with-big shocks)

Can't even begin to tell you how much I appreciate your help.  I'll do it as soon as I get home! 

[allroy1975]

ok, obviously I'm not expert but I fired it up and did just like you said....I'm guessing my lights shouldn't have dimmed and that spark shouldn't have happened.  I deceided to try to figure out where the wires were going.  first thing I did was (well..unplug the machine of course).  Started with something I know how to do: Test connectivity. 

I put the thing on the >| and put one in the positive and one in the ground of the monitor power cable.  and the numbers started dropping...like there's connectivity, but not all the way to 000, only to about 300ish.  That seems BAD to me.  Nothing happens when the machine is on...I would think if the two were touching there would be sparks and maybe smoke?  So..I figured out the Ground does go all the way back to to the ground point back behind that thing in the 3rd picture.  The Positive side seems to go to 3 places...

1. to the exact same post thing that the power from the wall thing goes to.  In the 3rd picture against the side of the cabinet it's the 3rd contact back.  tested perfect connectivity to the plug that goes into the wall from the monitor plug.  Where's the Islolation transformer??

2. & 3. seems to check out to the far right black and white wire on that black box in the 2nd picture.

A lot of this seems bad/wrong to me...but that's why I'm here asking for help. I don't have a clue how all this is supposed to be powered.

Thanks again to everyone for the help thus far.

Allroy

[grantspain]

basically your wiring should be as follows;
mains lead into the cab then through a mains filter,(maybe an on/off switch)then into an isolation transformer then you have 110v to your monitor,obviously all metal work should be earthed-its all pretty basic really,all you need to prove all this is a meter
use your meter to check continuity in the wires checking earth goes to earth etc,then you can check at different points where your mains is present,remember it does not matter what way round the meter leads are on mains as its a/c-i would start by check the earth continuity from any metal on the machine(that is earthed) to your mains plug,then i would check the a/c 110v at the point it enters the cab then after the isolation transformer and then at the monitor plug

[grantspain]

blimey that wiring is a mess epsecially around the iso transformer,look at pic 3 thats your iso transformer-i guess the thick black 2 core cable goes to the monitor-why have those fuse holders got no fuses in them???

[allroy1975]

no, it doesn't go to those fuses...I'm thinking I should just learn how the monitor SHOULD be wired to the Isolation Transformer and do it.  That's the only thing in the cabinet that needs power right now.  and whoever did ....this....to this machine mad a huge mess.  There's more messy splices in this machine than I've seen in my life.  He's got uncovered splices in there.  it's just a wreck.

so I'm thinking about just taking everything out and working with it until I can get the monitor to glow.  is this a good idea?  bad?  why?

[Grauwulf]

If the wiring in that cab is that badly hacked, you should probably be thinking about re-wiring the entire thing. If you don't, you will likely have no end of random intermittant problems. Just my $0.02 worth.

[grantspain]

rewire it ,its so easy;
mains lead-mains filter-psu/iso transformer,all metal earthed to a central point(usually transformer or earth block just after filter)-meter a/c voltages-all o.k connect monitor.its a half hour job and peace of mind

[allroy1975]

any particular gauge of wire I need to use if replacing some?

[grantspain]

depending on the amp drawn,i use standard mains(we are different in europe,we have 240 v mains) 13 amp mains for mains lead,and to psu/monitor also i put inline fuses(usually 3 amp anti surge) on each cable going to monitor and psu(just as extra protection)-you are gonna be different in states,but i reckon you can reuse most of your cable,it just needs tidying up a bit and some fuses

[allroy1975]

so......where do I go in, and out of the monitor..the monitor needs 120v AC, right?

I'll make 5 connections total right?  the 2 wires that are + and - on the power in, the ground and then the + and - that go to the moniotr.

Where should I put all these?

edit: forgot to add a picture of the transformer

[Kevin Mullins]

What game do you plan on running in this cab? (cocktail)

I see that there is already a switching power supply in there...... so I don't see the need for the Midway one depending on what you are putting in there.

As for the AC wiring/monitor wiring ....  http://homearcade.org/BBBB/acwiring.html (ignore that it's refering to a Ms. Pac....this is a basic layout)

[allroy1975]

I was planning on trying to hook a PC up to the arcade monitor.  I actually had it up and running in the Upright cabinet that way, so it should be fairly simple once I get the whole Power to the monitor figured out. 

Thanks for the link, that looks like just what I needed.  I'm pretty sure I blew something on the moniotr, so I'll post back once I've rewired the power.

Thanks again.

[worm]

if it's blowing fuses check he brige first then check the H.O.T along a cap kit.

[allroy1975]

alright I'm redoing everything.  According to Bob Robers page, linked above, the power comes in basicly straight to the Iso Transfomer....However, his has 2 ins and 2 outs...like this on from Happ controls.  My Isolation transformer has 4 on the "bottom" and 7 on the "top".  I understand a little bit that there are different types of transformers that can put off multiple different voltages, to either give lower or even higher voltages...right?

So what do I hook to where on mine?

the "top" I'm thinking would be the output with 7 differnt terminals are labled:
16.5   9   0   9   16.5   0   12

the "bottom" I'm thinking should be where the power comes in and that is labled:
0       6.3      105      115

It's an old Midway MT-58 and unfortunatly Google turned up no useful information for me. 

Since I hope to run a PC in this cocktail with MAME on it, I think All I need to do is get the monitor working and the rest should be easy. 

Can anyone advise where I should hook my 2 power wires to?  and then to the monitor?  and the Earth/Ground all just goes to one common spot. 

and I guess while I'm thinking of it, should the monitor Chassis be connected to Earth/Ground at all?

thanks again for everyone's input. 

[SirPeale]

That doesn't sounds like an isolation transformer.  It sounds like the power transformer for the game.  I say this because isolation should be 1:1.  You haven't listed a voltage around 115 volts.

You sure that's the only transformer in the game?

[Ken Layton]

WARNING: that MT58 transformer is NOT the isolation transformer! That's the power transformer for a Galaxian/Pacman gameboard. That's why all those wires were cut was because someone installed a switching power supply, hence the gameboard transformer was no longer needed.

There should still be ANOTHER transformer in that cabinet which would be the isolation transformer.

By the way, your VideoMaster monitor is really a Kortek KT-1420a monitor. These monitors are known for having the flyback go bad and arc to the chassis near the focus knob. Bob Roberts sells the flyback for this model. Likely it also needs a cap kit as well as resolder the many numerous bad solder joints too.

[allroy1975]

awesome! 

That's what I was starting to think after checkin my Jr. Pac-man cab.  It had 2 of them and the one that I have (in this cocktail) doesn't look like the one that powers the monitor.  This cocktail cab only has the 1 transformer so I'll have to pick up an Isolation Transformer. 

Yeah, the monitor WAS working perfectly with a great picture in that upright Roadblasters cab, but I stupidly hooked it back up in the cocktail assuming whoever wired it up did it right.

There's also that Switching power Supply in there that I pictured earlier.  That won't power the monitor?

[SirPeale]

There's also that Switching power Supply in there that I pictured earlier.  That won't power the monitor?

No!  All switching power supplies do is convert AC voltage to DC voltage. 

A monitor runs off AC voltage.  But in older monitors it must be isolated.  Hence the use of an isolation transformer.

[allroy1975]

There's also that Switching power Supply in there that I pictured earlier.  That won't power the monitor?

No!  All switching power supplies do is convert AC voltage to DC voltage. 

A monitor runs off AC voltage.  But in older monitors it must be isolated.  Hence the use of an isolation transformer.

Awesome.  New Isolation Transformer...here I come!

[allroy1975]

alright, I've got an isolation transformer (I think)

still, what's in and what's out?

[allroy1975]

Okay, back to my task at hand here...


I finally bucked up and spent about $40 on a couple Isolation transformers from happ Controls.  I built the Bob Roberts power assembly recommended by Kevin.  So now I have 2 arcade monitors I'm working with and here are their symptoms:

-  Electrohome GO7 This is the one that's ACTUALLY blowing fuses

- a nice Kortek KT-1420a according to Ken, a K1-2-V0 according to Bob Roberts What's My Monitor page  This is the one I had working and stupidly plugged it into the old cocktail it was in without testing ANYTHING and it glowed very brightly for a second then just shut off.  The only fuse I can find on it is good. 

I've plugged both monitors into this new little power rig thing.....

The Electrohome still blows fuses (eliminates problems in the cab as far as I'm concerened...)

The kortek is still dead.  I suppose its quite possible it arced and burned, but how can I tell for sure?  I don't see any scortch marks or anything.  Also, I think I said before that I initially had this monitor out and put it in to replace the Electrohome and it worked GREAT, had a fantastic picture and even ran great with a regular AGP video card and a home made cable in DOS using a Dosmame and ArcadeOS.  Would the caps etc still need to be replaced?  I guess it's one of the most basic troubleshooting things to do on a montior, but does it affect power?  I seem to not be getting any power distributed to the monitor.

Something that strikes me odd is that the power going to the Isolation transformer is 120 but the secondary is outputting almost 10v more than that...what's that about?  just too many windings on one side?  it behaves this way on both Isolation Transformers. 

The Power Distributer is sending 120v to the Isolation transformer:

The Isolation transformer is outputting 130v almost


Again, any suggestions, help, ideas ...anything are VERY welcome and appreciated.

thanks

[Ken Layton]

The output of any power transformer will read higher when there's no load (i.e. the monitor) connected to it.

[allroy1975]

oaky, that clears that up.  Any idea what direction I should head now?

[grantspain]

you should listen very carefully to the chassis to see if you get a chirp from the psu area,yes then look towards h.o.t,caps or flyback-no then looks towards bridge rectifier or diodes on the mains input primary circuit-i believe the electrohome is either the ptc or  a diode

[Grauwulf]

Which fuse is blowing on the G07? The small one, or the big one? It makes a difference as to where you need to look.

[allroy1975]

GRRRRRRR......

Okay, I talked to the tech who repaired my monitor and explained how that monitor was blowing a fuse..told him it was still happening with my bob roberts power rig.  Of course I didn't remember and didn't go back and read, but now that I do...I see grantspain suggested that it could be the degaus coil.  The reason I didn't think it could possibly be the monitor was because I saw it work at the tech's house with my own eyes!  thought for sure something must have happened on my end.  Turns out there WAS a torn/worn spot on the degaus coil itself.  I pulled it out, used electrical tape to fix it up and it started working great.  So..next thing to try...put it back in the cabinet.  Hook up to the power from the cabinet turn it on.  Works! 

Next step, hook up the video from the game to the monitor.  I do that, turn it on....blows a  fuse!!!!   

replace fuse....pull the video from the game power back on...blew my last fuse.   

F this.  I'm done for the night....I'll get more fuses tomorrow and start killing them again. 

[grantspain]

unplug the degauss coil from the chassis and test monitor,it must be something shorting on the coil otherwise it would not have worked outside the cab

[allroy1975]

So..next thing to try...put it back in the cabinet.  Hook up to the power from the cabinet turn it on.  Works! 

See?  It was working In the cabinet.  All was good and I was very excited.  Then I plugged in the video.  All I did was plug the RGB etc into it....So I couldn't have moved the monitor around THAT much while plugging in the dang video.  Still, I'll go over the whole thing tonight. and check it out.  Just wanted to post last night that I had SOMETHING on one of the monitors.

Also while talking to my local monitor tech last I asked him if he knew anything about those kortek monitors and he said "that they're junk".  Said he doesn't really work on them, so...Im on my own there.  I'm starting to understand some of this a little better though...I think.   

[Ken Layton]

Anytime you blow a fuse on the monitor when you connect the gameboard video signal to it, I've found that switching power supply for the gameboard is connected improperly to the AC power line.

Remember that the only thing that should ever be connected to the secondary (output) of the isolation transformer is the monitor. That's it's purpose: to ISOLATE the monitor power from everything else lest you blow up something. Follow the two AC power wires from your gameboard switching power supply. They should NOT be connected to the output of the isolation transformer.

As to the Kortek being called junk by your tech, I beg to differ. Some problems can be traced to numerous bad solder joints (much the same as Wells-Gardner has soldering problems), flyback problems, (the same as Wells-Gardner and Electrohome), a blown horizontal output transistor (like a Wells-Gardner), bad capacitors, (just like any other monitor), or a bad voltage regulator (again just like a Wells-Gardner). I wrote a repair guide to the KT-1420A.