Problem powering my WG 25k7193

[darthphunk]

Hello!

I picked up a Dynamo cabinet with a Wells-Gardner 25k7193.

It's been gutted, so I need to provide AC power to the monitor.

After poking around on the net, I found Bob Roberts instructions on how to accomplish this here:

http://www.therealbobroberts.net/buildit.html

My set up is ALMOST identical. The only thing I am doing differently, is I do not have an AC power switch, nor am I using a switching power supply. so my setup goes AC POWER CORD to 3AMP FUSEBLOCK/AC FILTER to DISTRIBUTION BLOCK to MARQUEE LIGHTS/ISO TRANSFORMER

This isn't mine, but this is exactly how mine is set up.  Same cabinet and monitor also...

http://codechunks.com/mame/  

My problem is, that whenever I start this up... I pop the fuse.  At first I thought it was because I was using regular fuses, so I got some slow blows and those pop immediately as well.

I first took the marquee light wiring off, still popped a fuse.  I then removed the wires from the AC filter... and the fuse was just fine. I then disconnected the monitor power from the ISO so the trail stopped there...  Power, to fuse, to ISO and that's it.  The fuse popped.

Could my isolation transformer be bad?  I'll try powering my cab lights first without being connected to the ISO to rule out a bad AC filter.

Any advice would be great.

EDIT:  I bypassed the ISO and hooked the marquee lamp up to the AC filter, and it works just fine.  The fuse only pops when I hook up the ISO.

[SirPeale]

Post a picture of the iso and the wiring to it.

[darthphunk]

Post a picture of the iso and the wiring to it.

I'll try to post a pic around lunchtime.

If not, it will be after work.

[darthphunk]

Here is a pic of my setup.

Right now, the marquee lights are disconnected.  The wires go off the screen, but the hot and neutral wires from the filter go to the distribution block, and in to the ISO. The blue and red wires go to the monitor (blue to nuetral, red to hot)

I blow the fuse though whether or not the blue and red wires are connected.

The fuse does not blow if the ISO is disconnected and the lights ARE connected.  They work fine.  As soon as the ISO is on the loop... pop goes the fuse.

Oh... and the green ground coming off the screw on the AC filter is connected to the screw on the right side of the ISO

[SirPeale]

Is the monitor connected yet in this setup?

[Kevin Mullins]

Is the monitor connected yet in this setup?

Blue and Red wires coming off the top of the ISO.

[darthphunk]

Is the monitor connected yet in this setup?

Blue and Red wires coming off the top of the ISO.

Yep.

And, the fuse pops whether or not the monitor is connected. The fuse does not pop if I an NOT connected to the ISO.  The lights power on just fine if I take the ISO out of the loop.

I know people say the ISO rarely goes bad... but I'm thinking I should pick up a new one.

[Kevin Mullins]

Is your ISO clearly marked with PRIMARY and SECONDARY ?
Primary is AC in, Secondary is monitor.
(typically it's like you have yours wired, Primary on bottom - Secondary on top, but I have seen some odd-balls around)

Take an Ohm reading between the two Primary tabs on the ISO, should see something like 4-5 Ohms, but NOT a direct short. (not zero)
Unplug your AC lines first, and no power of course.

Also take a reading between the primary and secondary tabs, should have NO reading between any combination of primary and secondary tabs.

[darthphunk]

Is your ISO clearly marked with PRIMARY and SECONDARY ?
Primary is AC in, Secondary is monitor.
(typically it's like you have yours wired, Primary on bottom - Secondary on top, but I have seen some odd-balls around)

Take an Ohm reading between the two Primary tabs on the ISO, should see something like 4-5 Ohms, but NOT a direct short. (not zero)
Unplug your AC lines first, and no power of course.

Also take a reading between the primary and secondary tabs, should have NO reading between any combination of primary and secondary tabs.

This is extremely helpful.

I will test this evening.

Thanks!

[SirPeale]

Is the monitor connected yet in this setup?

Blue and Red wires coming off the top of the ISO.

That didn't mean they were connected to the monitor above, which I can not see.  But now that that's been established...

Do follow Kevin's advice.   Like I said, it's unlikely that it's bad - but "unlikely" also carries with it the possibility that it is.  I'll be curious to see the outcome.

[darthphunk]

Is the monitor connected yet in this setup?

Blue and Red wires coming off the top of the ISO.

That didn't mean they were connected to the monitor above, which I can not see.  But now that that's been established...

Do follow Kevin's advice.   Like I said, it's unlikely that it's bad - but "unlikely" also carries with it the possibility that it is.  I'll be curious to see the outcome.

Not  to beat a dead horse, but I actually did specifically say...

"The blue and red wires go to the monitor (blue to nuetral, red to hot)" 

I will test shortly and let everyone know of the outcome.

Thanks everyone for your advice!

[SirPeale]

"going to the monitor" and "connected to the monitor" - English is a funny language.

Eagerly awaiting your results.

[Kevin Mullins]

That didn't mean they were connected to the monitor above, which I can not see.  But now that that's been established...

Yeah, that crossed my mind well after I posted that, but recalled him saying it didn't matter if it was connected or not so figured it was an irrelevant sorta thing.

Ah well...... let's poke around that ISO a bit shall we ? 

[MonMotha]

FWIW, a shorted secondary can cause some "interesting" issues, as well, so check to see if the secondary is shorted while you're probing around that transformer.  Conditions should be similar to the primary (low but non-zero resistance measurement).

[darthphunk]

Hey all...

I'm getting a zero reading when testing the ISO.

So I'm thinking I need a new one.

Thanks for all your help!

[Kevin Mullins]

Just to clarify..... was that a zero OHM reading or a zero CONTINUITY reading ?
(don't want to confuse the two)

[darthphunk]

Just to clarify..... was that a zero OHM reading or a zero CONTINUITY reading ?
(don't want to confuse the two)

I think I measured the Ohms... I know it wasn't resistance.

Please tell me what setting to use and I will double check...

Here is my meter...

[MonMotha]

Resistance is measured in ohms.  The quantity you are measuring is "resistance", and the units are "ohms" usually abbreviated with the capital greek Omega.

You want the blue "200" setting right next to the blue "2k" setting.  A reading of 0 across the two terminals of a winding (primary or secondary, not from one to the other) indicates a shorted winding (fault).  A non-zero but low reading (~3-5 ohms) is normal.  A high or infinite reading indicates an open winding (fault).

[darthphunk]

Resistance is measured in ohms.  The quantity you are measuring is "resistance", and the units are "ohms" usually abbreviated with the capital greek Omega.

You want the blue "200" setting right next to the blue "2k" setting.  A reading of 0 across the two terminals of a winding (primary or secondary, not from one to the other) indicates a shorted winding (fault).  A non-zero but low reading (~3-5 ohms) is normal.  A high or infinite reading indicates an open winding (fault).

Ok... I was using the wrong settings. I had it on 2M

On the primary (bottom... it's labeled) I am getting 1.5

on the secondary, I am getting 6.0

[Kevin Mullins]

Primary (AC/Fuse side) seems way low..... 
Secondary looks fine.

Checking a brand new one I get @4.1 on the primary and @5.2 on the secondary.

[MonMotha]

Resistance of the primary will vary depending on construction and can be lower than you might expect for a given secondary resistance for a certain class of transformers known as "inherently limited transformers", but I agree, that seems low.  You probably have a shorted primary winding.  I'd recommend trying another iso xfmr.

[darthphunk]

Ok then...  The new ISO is in.

Now, it takes about 30 seconds for the fuses to blow 


So there may be something wrong with the monitor as well. I think I am going to go back to my Scramble restoration project for a while and come back to this with a fresh start.

I'll check the flyback... anywhere else to check?

[Kevin Mullins]

A bad monitor should NOT blow the fuse on that side of the ISO, it would blow the fuse on the monitor chassis itself.

What size fuse are you putting in there ?

Take a pic of the power connector at the monitor itself.

[darthphunk]

A bad monitor would NOT blow the fuse on that side of the ISO, it would blow the fuse on the monitor chassis itself.

Would a bad monitor fuse blow the fuse before the ISO?

[darthphunk]

A bad monitor should NOT blow the fuse on that side of the ISO, it would blow the fuse on the monitor chassis itself.

What size fuse are you putting in there ?

Take a pic of the power connector at the monitor itself.

The fuse before the line filter... when it blew after the ISO was a 3 amp slow blow.

I pulled the fuse from the monitor chassis and looked it over. It looks ok, but it's failing a continuity test on my meter.  It's a WG 25K7193.  Any idea what size fuse goes there?

My camera is crapping out so I'll draw a diagram:



Is it possible I have the blue and red wires backwards?  If I switch them... will it do any damage or will the fuse at the line filter pop again?

I'll try to post an actual pic tomorrow.