Noob - MK (Midway) cabinet - WG 25k7197 power issue...

[edacra]

Just picked up a MK (Midway) cabinet (without pcb)...  the electrical and wiring was messed up...after much lurking and reading (this is a great forum) I was able to get the electrical working after changing the fuses in the iso trans and rewiring some components... I have power to the marquee, coin door and to the switching power supply but can't seem to get the monitor to fire up...apparently the monitor was working before the game board was pulled (unfortunately there was no way for me to test the machine given the condition of the wiring when I picked it up)...before I dove into messing with the monitor (i'm a little hesitant given all i've read about crt voltages) I just wanted to confirm that I'm not missing anything and that the monitor should turn on without having a game pcb in the cabinet? any input is greatly appreciated...

[SirPeale]

Yes, the monitor should fire up without a PCB.

Let's see some pics of the wiring.

[gokun]

this is probably a dumb question, but you do have the power line(s) from the iso transformer going into the monitor, right?
I sometimes forget stuff like that when I have been re-wiring a lot of stuff so thought i'd ask just in case.

[Kevin Mullins]

You should have a pair of purple wires coming off that ISO transformer going to the monitor.
(one solid, one striped if I recall)
These Midway cabs have caused some confusion in the past, so pics of your current wiring status would help.

If power has been applied to that K7000 without the iso..... expect it to be damaged.

And as Peale mentioned, the monitor should "fire up" without a pcb, but don't expect to see much unless you turn the screen voltage up or something. There will be neck glow on the backside of the monitor, but the screen should remain pretty much black unless turning the screen, brightness, etc way up.

[edacra]

Peale...thanks, i figured as much but thought i'd ask...

Kevin... you're absolutely right - the iso trans has four purple wires (2 solid 2 striped) coming out from one side, 2 of which go to the monitor and the other two go up to the marquee light / speakers (along with others)... the two purple wires that feed the monitor are "tapped into" before going to the monitor and this "tap" sends two other purples wires to the AC input on the switching power supply... none of the wires have any tears in them that I can see and the solder points on the iso trans seem intact... I don't know why the monitor would've been used without the iso trans and the fuses in the iso trans were blown when I picked up the machine...

I read a lot before putting the wiring back together so hopefully everything's put back together correctly... I also remember reading that the Midway cabs can have some quirks in their wiring... i'll recheck the wiring tonight and try to post a couple of pics...

[Ken Layton]

Some of these Midway cabinets did indeed have the isolation transformer wired incorrectly!

[edacra]

When I got home last night I rechecked the wiring and reseated all the molex connnectors...turned the machine on - nothing...I then checked the voltage going to the monitor (the solid purple wire) with a multimeter - 135 volts (I'm assuming all good)... I then checked the monitor fuse for continuity (all good)... I examined the monitor board with a flashlight and took a couple of pictures of the wiring... turned the machine off...went to go get a beer... came back,  powered up again and heard that wonderful crackling and buzzing of the monitor firing up... the neck starting glowing ...I have no idea what i did or how it happened but it appears to be working (hopefully it stays lit)... maybe it was the beer...thanks for all your feedback...

[Ken Layton]

Connector problems probably caused it to start working. Maybe one was fully seated?