Is the varistor you are talking about the one on the power supply board that handles the coils? the schematics are very bare. I dont have a system 6 so I can't go peak whats in it but I can at least answer your other question. Soldering wasn't the problem. The varistor had to have been bad to start with, its kind of a common thing for them to catch on fire.

No it's on top of the AC circuit, below the playfield, mounted to the left side of the cabinet. Pictured here:  http://pinball.flippers.info/system6acpower.jpg
That's good to know it wasn't the soldering.

Getting crickets over at KLOV and Pinside on this question. Wondering if there's anybody out there with a Williams System 6 pin that can look at the varistor on the AC circuit and tell me what type it is?

Also just some technical questions: I picked up a Williams Firepower that was powered with what looked like a lamp cord, I replaced the cord, blew a fuse that was turned out to be the wrong fuse. Put the right fuse in, noticed the varistor on the AC circuit was broken and I probably made a dumb move by soldering the varistor back together. When I turned it on, the varistor blew and caught fire.

So first question is, I'm not sure what type of replacement I would need for the varistor as the one that blew is pretty much destroyed--does anyone have a Williams System 6 that knows what varistor is needed? Second question, is soldering that varistor what caused it to blow or is there a deeper issue at hand? Despite the fire the machine was lit up for the quick moment it was turned on.

Holy shit snacks! I tried this search string and immediately found a "pin ball what takes a " and 24 hours later I picked up this beaut for $150:

http://imgur.com/a/kkApD

First of all Steve Richie is my favorite pinball designer, and this is a Steve Richie design, and this is the first Steve Richie I am adding to my collection . Second,  according to pinside: this is the first pinball to use multiball, the first pinball to use a flipper as a way to change lane lights, and the second pin to use speech (Gorgar used 3 words of speech, Fire Power used 7). I am beyond stoked.

We plugged it in with a cord that looked like it came from an old lamp and it immediately caught on fire but this is an absolute steal.

I would like to thank John for teaching me how to exploit them cricket eating hill folk what beset me from all die-rections.  Yeow!!!!


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If you are getting around 5V measured at the PCB then you are fine. just make sure both PCBs are getting 5V as they don't share the same power supply.


It sounds like you did that though and your next step should be getting the board out of the cabinet and prepare for board repair.

Get the board out, inspect it, take photos and post them here. I see that pattern often when the z80 sound processor is dead or the 52XX custom chip is dead/damaged/missing


Check around the battery, make sure its GONE and there isnt any battery acid damage. That is a very common failure and it usually takes out the z80 as well as the reset circuit.

Iankellog-

Thanks for helping me troubleshoot this.  To clarify, I tested 5v wires before they touched the board. Should I be testing directly on the board when connected/plugged in? There is no corrosion of the battery that I can see, but if I remove the battery, do I need to bridge the gap it leaves with wire?

I inspected the boards and found a few suspect areas. I posted another album-- this is as high a res as I could get w/ my phone but I could potentially use a better camera.  Suspect areas are circled in red: http://imgur.com/a/pkwzV

The soldered wires might be jumpered wires for the voltage mods like I showed in my Pole Position bullet proof video.

Someone on KLOV directed me to your Bullet Proofing video. Once I watched it I understood that (as you say here), the soldered wires were bypassing the harness to the edge connector, which had been retinned on Pin A on the first board and Pin A & B on the second board. I desoldered them, cleaned them up and and jumped them to test points on the board.

I tried the bullet proofing as per the video-- was very meticulous about it, triple checked my work. Before I did the bullet proofing, the game would at least play, it just had a screen that was looking pretty crazy.

When I plugged it in after the bullet proof mod it went straight to a stuck garbled screen. I unplugged it immediately, double checked again, I feel like I did the right thing as described. In the video you had the wires going to all the appropriate test points on the board, which is how I did it-- but to make sure I hadn't made an error I removed all of the bullet proofing wiring and tried only tapping into one test point for the 5v and one for the ground for each board. This did not change anything, I still had a frozen garbled screen.

I used the ground wires going to the A pin on the edge connector each board and bypassed them to a ground test point, and the 5v wires going to the B pin and wired them to the 5v test point. On the pinout I did notice that there is a second 5V at pins R  on one board and Y on the other- should I be diverting those as well?

I pulled up and reseated all the chips as well.

Iankellog- I tested the 5V wires and am getting a solid 5V on each  are you suggesting I bypass the entire harness with all the wires to various test points on the board? I know how to test for voltage--  but most of these are ground wires-- how do you test a ground wire exactly? Forgive my ignorance.

Hi all-

Noob here. After watching some of John's tech videos I decided to buy a couple troubled games and try to fix them myself.  I have some experience fixing older pinball machines, mostly parts replacement and some light work on PCBs replacing parts and reflowing soldering.

When I bought Pole Position, everything seemed to be working fine except that cars and signs in the distance were appearing as blocks.  However, shortly after I brought it home it started having a garbled screen and the sound was going bonkers.

The test screen says that both RAM and ROM are okay. 

Here is a photo album of suspect things I've found in the cabinet with descriptions --- some cut hanging wires, wires soldered to the PCB, a disconnected fan, a bunch of unattached ground wires: http://imgur.com/a/lYd9V

I haven't pulled out the boards because some of the wires are soldered directly to the PCB and I didn't want to start messing with it until someone can suggest a solid plan of action for getting this machine working again. 

I'm comfortable with testing voltages and replacing parts on the PCB, but my knowledge about where to test voltages and what to change out is pretty much zilch.

Thanks in advance for any suggestions.