NARC AC line voltage problem

[Arm123]

I have a NARC that is in great cosmetic shape, but is not working.

Is there anyone out there, who is familiar with these ?

I started at the power block (black box, looks like a transofrmer) that plugs into the wall. I seem to only get 80V AC out of it.

This power block feeds the AC line filter, which is mounted under the isolation transformer.

I decided to bypass that power block and plug the AC line filter directly into the wall.

I get 120V AC out of the line filter and up to the monitor chassis AC input. Then back to the isolation transformer power input, i still get 120V AC.

However, at the power output of the isolation transformer, I get 80V max, with nothing plugged into it (no boards / monitor).

I get 50V or less when the rest of the components are connected. This isn’t enough to power the game. So it seems that the isolation transformer is the problem.

I have never wired a isolation transformer, but I know its not supposed to be a big deal. However, this one looks to be specialized for NARC / Williams games, so im not sure what to do.

Any suggestions ?

[MonMotha]

Many cabinets feature transformers used for more than just monitor isolation.  This was very common on Midway games, for example, and I therefore wouldn't be surprised to see it on other WIlliams stuff.

These transformers often have two or more AC outputs.  One is used for the monitor, and the other is used for "everything else".  The input can be jumpered for multiple input voltages.  Given what you are seeing, it sounds like it's probably jumpered for 240V in rather than 120V.  If you can find a manual for the game with AC wiring, you can likely verify.

Also, as you describe things, you are NOT running the monitor off isolated power.  If the monitor requires an isolation transformer, this is very bad.  Check your monitor specs.

[Arm123]

Thanks for the reply...

I did suspect that the 'extra' transformer did something, so in by passing it, i made sure that the monitor's AC was unplugged during my tests.  So no danger there.

I can follow the AC from the wall.. to the line filter...  to the games main 4 prong toggle switch...  back to the input on the isolation transformer.  120V AC checks out fine.

The AC output from the isolation transformer is connected in parallel to the switching PSU and then then monitor.  As i stated, i get 50V to 80V AC on this line.  The PSU will not power up...  so i have to assume its this isolation transformer thats causing the problem.

Its just strange, because iv never seen an isolation transformer that looks like this.  So it must be for more than one thing, like you say.

Ill post some pics...

[MonMotha]

50-80V out (it will vary unloaded vs. loaded) is consistent with ~120V in with the transformer set to ~230V.  That's why I say you should check your transformer wiring.  Those Midway transformers could be wired up for something like 6 different input voltages.

If that's not it, it's either a blown fuse (and you can still measure things due to neutral/ground shifts on isolation transformers) or a shorted transformer.

[Arm123]

Cool...  Thanks MonMotha

Im going there today, so ill have a look and double check.  Would be great if thats all it was.

[Arm123]

Here are some pics i snapped...

This is a pic of the all the power rigs.



Here is a pic of the first transformer that is plugged into the wall.  Then the isolation transformer plugs into that.



Here is a pic of the PSU.



Here is a close up of the sticker on the isolation transformer.



Model number of the monitor.




Is it possible that the first transformer is for converting the power some how ?  I don’t even know what its for.

Any ideas... ?

[SirPeale]

That first transformer appears to be either a pull up or pull down transformer.

Where do you live? 

If it's an American cab that went overseas, I can see needing the 110V --> 220V up conversion.  Or the other way around, a foreign cab that came to the states.

Check the power supply, see how it's been jumpered, for 220 or 110.

[CheffoJeffo]

Arm, you're here in Toronto, right ?

My bet is an Ontario Hydro iso, which is in addition to the ISO for the monitor and all power in the cab has to run through it for the game to be "legal".

The Isolation Transformer,was made Mandatory after an unfortunate tragedy on Younge st in Toronto mid 70's.Those Old Chicago Coin Rifle games had an Impact Coil for the Rifle Base that ran directly off Line Voltage,all the Machines in this Arcade were wired for 240VAC.Mr Curry stepped in a Salty wet floor pulled the trigger and suffered a Fatal Electrical Shock;rather than Identify the Problem the  Goverment decided to put a Blanket fix on the Hazard,unfortunatly the next Generation of Machines with +5volt/5millaAmp inputs was just around the Corner

http://s107351202.onlinehome.us/cgi-bin/Blah/Blah.pl?v-print/m-1181307875/

EDIT: But definitely check to see how things are jumpered before you use it as a boat anchor.

[Arm123]

Thanks guys... yup, im in TO.

Pretty sure i checked the PSU and it was jumper set for 110/120V AC.  I will double check this though.

I have disconnected the PSU and other components, from the AC line, for fear of bad power.  I wanted to get the correct AC power to the PSU before I connect anything else.

Just a guess though...  I will confirm tomorrow when I go to my storage unit, this is a Euro cabinet.  I say this because of the sticker on the isolation transformer, rated for 250 V ?

I know the monitor is 120 V...

In my previous post, i did state that i tried by passing the step up / step down transformer with success.  Very odd stuff.  I’m still leaning towards the isolation transformer being bad.

Anything suggested diagnosis for tomorrow ?

[MonMotha]

That larger one looks identical to the transformer I found in my MK2 cabinet (removed since I did not need it at all).  It can be jumpered for various input voltages.  Instructions were in the manual.  I do believe that both AC outputs were isolated (from each other as well as the input side), which would render that other transformer unnecessary.  Perhaps it was added for legal reasons as stated above: many electrical legal directives have little consideration for actual electrical situations since they try to come up with a rule that can be universally applied.

If the first transformer (the small one with the standard AC plug output) is giving you 50-80V out, then it's either busted or a step-down.  Either way, you shouldn't need it.  Just remove it and don't use it.  Verify that the other transformer does in fact isolate its monitor output, though.  Also verify that the Midway transformer is set appropriately for your local line voltage.

[Arm123]

One of the first things i did was to try an by pass that 'step up/step down' transformer, by plugging the other transformer right into the wall...  This still only gives me 80v / 50v AC out of the main transformer (not the 'step up/step down' transformer).

Not sure what to make of it, other than making me think that the isolation transformer wants me to feed it 230v - 250v AC or its broken / malfunctioning... ?

[RayB]

Ditch that extra iso and use the plug that is currently plugged into it.

[Arm123]

Thanks guys...  However, you can see from my other post that i already tried bypassing that black / stepping ISO transformer and plugged the main ISO transformer into the wall. Still the same result.   

Is it possible that the main ISO transformer wants 230v - 250v ?

[MonMotha]

Is it possible that the main ISO transformer wants 230v - 250v ?

Absolutely yes.  Check the wiring diagram in the manual for whatever that cabinet started life as.  I have that exact transformer and it can be wired for a whole bunch of different input voltages, including things in the 220-260 range.

[CheffoJeffo]

Is it possible that the main ISO transformer wants 230v - 250v ?

Yes, it is possible, BUT don't be confused by the warning about fuse ratings -- 3A, 250V ... every glass fuse I have seen in a pin or vid is rated for 250V.

* CheffoJeffo picks up the fuse he just replaced in his F2K to double-check in case he is losing his mind

Yep ... fuse rated at 250V.

Your PS expects 120. Your monitor expects 120.

Where did you get this (e.g. can you ask the previous owner ?) ? If this thing is running an Ontario Hydro ISO, I can't see it being wired for 250V, but let's rule that out before proceeding. Alternatively, maybe someone messed with the lugs/connectors trying to get it to work (again, where did you get this ?).

Before we got much further that that (e.g. turning the first ISO into a boat anchor) perhaps we should establish that the monitor is isolated -- is the power to your monitor running directly from the monitor to the transformer in the center of the cabinet base ?  You said that the power supply is fed in parallel to the monitor, both from the ISO ?

Also, where is your storage unit ? i'm pretty much tied up with family (6 members arriving today) for the next week, but I might be able to arrange to get there and look at things more hands-on.

Oh yeah, have you checked the fuse ?

'Coz, you know, it's probably just a fuse. Easy fix. It worked fine until I moved it. Really.

 

EDIT: MonMotha is too damned fast.

[Arm123]

Hey there guys...  thanks for the help and offers (Jeffo).  I made a bit of progress today.

I started by removing / rechecking the 2 transformers for jumper blocks for power output ranges.  There was none found on ether one of them.  So I guess this cant be changed.

I rechecked my readings on both ISO transformers to make sure I wasn’t high / stupid the other day.  Same B.S. results of 50v AC with the game PCB boards plugged in and 80v AC with the boards unplugged. The PSU gave no output ether.

I then decided to unplug the AC line from the florescent lamp and scored another 7v from the output of the main ISO transformer (87v).  I thought this was odd...

I decided to take the AC wires coming from the AC line filter (coming from the wall) and connect them directly to the input on the main ISO transformer.  Thus by-passing / eliminating the wiring that goes to 4 prong toggle switch, then threw the 3 cherry kill switches.  This made the transformer make a sound that I had not heard before...  It sounded like it was powering up !

I took some voltages on the out put / isolated side and saw that it was giving 170v AC.  That’s better but still not good....   So I then decided to put the black ISO transformer back in and plugged it into the wall (remember it gives 80v AC).  I though maybe it would help step down the 170v, by giving the main ISO transformer 80v instead of 120v.  Plugged the main ISO transformer into the black ISO transformer and presto !..  I got 110v - 115v AC.

So i guess i can conclude that the wiring, going from the AC line filter to the toggle switch, cherry kill switches and marquee light are causing excess load / fault ?  Cuz that’s the only change from the original wiring I this thing came with.  By passing that line of connectors made the main ISO transformer power up / give correct power.

I still need to do some more tests on the power supply before i plug the boards and monitor in.  Any thoughts on this whole situation ?

BTW: I bought this thing from Starburst auction for $25.

[MonMotha]

I started by removing / rechecking the 2 transformers for jumper blocks for power output ranges.  There was none found on ether one of them.  So I guess this cant be changed.

It's not a jumper block.  On the transformer from my MK2, Midway brought all the input taps out to the AC input connector.  Looks like the same situation here from the picture. The other side (cabinet side) is then jumpered to wire things up as desired for local line voltage.  However, it sounds like something on the output of the transformer may be shorted from your description below.

I decided to take the AC wires coming from the AC line filter (coming from the wall) and connect them directly to the input on the main ISO transformer.  Thus by-passing / eliminating the wiring that goes to 4 prong toggle switch, then threw the 3 cherry kill switches.  This made the transformer make a sound that I had not heard before...  It sounded like it was powering up !

Transformers in general should not make noise other than a very light 60Hz (or 50Hz in Europe) hum.  If it sounds like a bunch of rocks in a tumbler, then either something is broken (and this can sometimes be fixed) or the secondary has a short somewhere (either in the winding itself or one of the loads).

I took some voltages on the out put / isolated side and saw that it was giving 170v AC.  That’s better but still not good....   So I then decided to put the black ISO transformer back in and plugged it into the wall (remember it gives 80v AC).  I though maybe it would help step down the 170v, by giving the main ISO transformer 80v instead of 120v.  Plugged the main ISO transformer into the black ISO transformer and presto !..  I got 110v - 115v AC.

Sounds like the mystery transformer (the extra one) is a step-down (or is overloaded), and the big one is wired in a step-up configuration.  My MK2 transformer had an option for 90V in, IIRC.

Check the wiring for that big Williams transformer.  Trace everything out by hand if you have to.  A connection table for various input voltages should be in the manual for whatever game it was originally made for.  If you set it appropriately for your local line voltage and no outputs are overloaded, everything should work just fine.  When you moved that wiring around, you may have adjusted the set input voltage.

It is possible that some other strange issue is at fault here and is causing the outputs to run low, and somebody chucked that extra transformer in as a quick fix to "make it work now".  It would be far better to resolve the actual issue if you can find it.  I see that the big Williams transformer has lots of extra outputs.  If any of these are overloaded, it can cause problems on other outputs.  Check everything.  Note that with no load, transformer outputs do tend to run a little high.

I hate to have excess transformers in a power path.  People often install them without regard for spec.  I actually yanked one from a machine I bought which was converted from 230V to 120V US use that was maybe spec'd to run at best the monitor.  I'm surprised nothing had caught on fire.

If you do want to continue running it in the configuration you have with the multiple transformers, make absolutely sure that the extra transformer is rated for what you are using it for.  Note that VA != W due to an annoying little thing known as power factor.  If a transformer is overloaded, it can become rather hot and cause a fire.  That would be bad.  I've seen LOTS of transformers installed without regard for specs in arcade games, so don't make assumptions that it's OK.

[Arm123]

Transformers in general should not make noise other than a very light 60Hz (or 50Hz in Europe) hum.  If it sounds like a bunch of rocks in a tumbler, then either something is broken (and this can sometimes be fixed) or the secondary has a short somewhere (either in the winding itself or one of the loads).

The sound it makes on power up is kind of the same as a crt when it charges up on power up...  then it just humms lightly.  Hope its not broken.

It is possible that some other strange issue is at fault here and is causing the outputs to run low, and somebody chucked that extra transformer in as a quick fix to "make it work now".  It would be far better to resolve the actual issue if you can find it.  I see that the big Williams transformer has lots of extra outputs.  If any of these are overloaded, it can cause problems on other outputs.  Check everything.  Note that with no load, transformer outputs do tend to run a little high.

I hate to have excess transformers in a power path.  People often install them without regard for spec.  I actually yanked one from a machine I bought which was converted from 230V to 120V US use that was maybe spec'd to run at best the monitor.  I'm surprised nothing had caught on fire.

If you do want to continue running it in the configuration you have with the multiple transformers, make absolutely sure that the extra transformer is rated for what you are using it for.  Note that VA != W due to an annoying little thing known as power factor.  If a transformer is overloaded, it can become rather hot and cause a fire.  That would be bad.  I've seen LOTS of transformers installed without regard for specs in arcade games, so don't make assumptions that it's OK.

It would be nice to have some sort of wiring diagram for this thing, so i can configure it for my power range.  I pulled out the main ISO transformer and looked at the sticker. It had 115V to 250V max on it.

When I did the 'by pass' of the black / mystery ISO transformer, I noticed that the output was 170v AC.

On the 9 pin connection header there were a couple connections on that were 'looped' together.  I removed them for the hell of it and observed that the output was changed to 90v AC.  Is that what you mean by 'configuration' ?  If so, i guess i had better find the wiring diagram and fix it for my power requirements.

This double transformer setup makes me nervous and id rather fix it to work properly.

[MonMotha]

To be clear, I don't want to imply that multiple transformers is automatically a hazardous configuration, but you do have to ensure they are all properly sized.  Also, in this case, something else fishy sounds like it may be going on (or you may just be having issues with having the big transformer properly wired).

And yes, those looped connections are how the transformer input taps are set.  Refer to the manual.

[Arm123]

Cool !.. thanks MonMotha.  Thats what i wanted to hear.

I have a firend who took the manual when i acquired this cabinet (1 year ago).  I getting it back so i can have a look and see if there is a wiring diagram for the main ISO transformer.