(Topic ID: 271026)

JackBot Left ramp help needed...

By indierocklocks

3 years ago



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#1 3 years ago

Hey guys,

I purchased a JackBot recently with some left ramp issues needing to be addressed. The little drop ramp magnetic coil was disconnected when I bought it & the power driver board had some burnt crispy components, which I was hoping I could just replace and have the issue solved. That's not the case and I'm kind of stuck now. Any help would be greatly appreciated....here is a list of what was cooked, what I've replaced, and the issues. I think the drop ramp coil (which teasted fine) is the main issue. That's located on the BRN-BLU wire on J127, pin 7.

-q48 was completely burnt. I replaced it.
-r81 was completely burnt. I replaced it.
-r80 was compeltely burnt. I replaced it.
-d19 was very close to the burnt q48. I replaced it.
-q47 was very close to the burnt q48. I replaced it.

The microswitch for "Ramp open" was detached. I got some screws and secured it. It does what its supposed to in switch edge test mode. The action for the ramp up & down is pretty smooth when I do it by hand. So I don't think it's a mechanical issue. I looked at the board for burnt traces, nothing looks bad. I reflowed the solder on the pins for J127.

Upon replacing the parts, I fired up the game and went into test mode. Ramp raise works just fine. But when I activate Drop Ramp, it works BUT the coil stays on and starts getting hot FAST....usually blowing a fuse.

I thought it might be U4, so I replaced that as well. No luck.

I double checked that I didn't get any bad parts but they seem to test fine with my DMM. The only two components I didn't touch were R78 & R79 in that circuit.

Here are the two manuals I've been using:
http://arcarc.xmission.com/Pinball/PDF%20Pinball%20Misc/Williams%20WPC%20Schematic%20manual.pdf (Page 5 has been mainly where I'm at)
https://www.ipdb.org/files/3619/Williams_1995_Jack_Bot_English_Manual.pdf

If you need any photos or have any questions please let me know.

#2 3 years ago

You can unplug the coil from the driver board and activate it in test mode then use a logic probe to walk backward from the driver board connector to see where the problem starts. I also have a WPC bench test rig, if you want some hands-on support shoot me a DM.

#3 3 years ago
Quoted from adalogue:

You can unplug the coil from the driver board and activate it in test mode then use a logic probe to walk backward from the driver board connector to see where the problem starts. I also have a WPC bench test rig, if you want some hands-on support shoot me a DM.

Sounds good! Appreciate the next step....Got my hands on a logic probe and I’ll be taking a look this weekend. Don’t tell my wife I’m downstairs probing Pinbot & Bride of Pinbot. Lmao.

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