bavacade Update 11-24-2024

I once again have a 100% working arcade, huzzah! Most of the work these days is shoring up the rest of the cabinets to get rid of any structural issues and put them on wheels. There are only two cabinets left to put on wheels: Cheyenne and Pole Position.* So those are up next, until then here’s the current tale of the arcade tape.

Stargate getting some much needed surgery on the lower area that was showing rot

The Stargate cabinet got some much needed refurbishing to deal with rot in the wood at the bottom. Re-painted it, the red was not exactly perfect—but close enough after a few coats.

Stargate with first coat of paint after work

When putting Stargate back together there were issues with the game resetting. It looked to be a power issue, so swapped inline power supply with switching power supply but was getting garbage. The garbage seemed strange given the board loaded cleanly with inline power supply, it was simply having re-set issues.

Multi-Williams FPGA Board

To further trouble shoot, I swapped in the FPGA board and connected it to the switching power supply, and that worked fine. Strange, so the FPGA board works well and does not reset. Back to the drawing board, I tested the voltage on the switching power supply and the 12V was low, close to 10V and the +5V was also low at 4.8. I swapped in a new switching power supply and plugged the board in and it loaded fine, no garbage. Nice! So one issue was definitely the switching power supply, the voltages were definitely off and while it worked with the FPGA (which seems to require less from the 12V and 5V) there wasn’t enough juice to power the original game boards.

Example of a switching power supply (this one from Pac-man, not Stargate)

While Stargate is working with the switching power supply, it does suggest there’s an issue with either the inline power supply or the Williams power board. So that might be another bit of troubleshooting down the line. I must say, Stargate has been a long-running project. It was the one game keeping me from a perfect arcade last fall. That said, with the new switching power supply and the original game boards working (not to mention the FPGA) it’s in a solid place now.

K4600 outside the Challenger as I prepare to swap it into Phoenix

The other project was to take the monitor and chassis from Challenger and put it into Phoenix. Once I started messing with the K4600 chassis on Challenger it stopped working, which led me to do a cap kit on that K4600, but the main board still didn’t work.

K4600 Chassis

I got another K4600 chassis on Ebay and that didn’t work either, but I was able to swap in the power board from the original, non-working chassis and it worked. For good measure, I swapped in the video and interface boards and at the time everything worked. So I brought the monitor to the arcade to swap monitors with Phoenix, but because nothing can be easy, once the K4600 was hooked up to Phoenix, the vertical and horizontal sync from the game wouldn’t work—which means I would need to work out what I was doing wrong with the sync wires from the PCB.

K4600 XY Video Board (missing the Vertical Hold Pot which needs to be replaced)

To make matters worse, while I was playing with the chassis I seemed to lose the ability to adjust the screen pot and the black level pots, so the colors were bleeding red and the entire image was bleached out. In frustration I abandoned the monitor swap idea and brought the Challenger monitor back home to test it further.

K4600 Interface board (model 305?)

Once re-connected I was able to figure out the interface board from the old K4600 was the culprit (which is where the black level is controlled), so now to troubleshoot what’s up there. I also realized the horizontal/vertical video board from the chassis I bought off Ebay needed to be re-capped, which I promptly did. After finishing I realized the vertical hold pot was broken in half, so removed it and ordered a new one.

Vertical Hold pot needs to be replaced

I once again have a working K4600 chassis, given the spare video and interface boards that come with an extra chassis. Now I’d like to get that extra K4600 chassis working. I’ll start by doing the following:

• Re-cap power board of new chassis from Ebay  (re-capped and working)
• Tested two K4600  fly backs and both are tested and working
• Replace vertical hold pot on XY video board mentioned above to see if that fixes the spare video board  Update: replaced the vertical hold pot, and this board works again!
• Re-cap (and probably more) the interface board from original 4600 chassis, start with a 1000 µf 50V capacitor Update: replaced the 1000 µf 50V cap, but no dice
• Continue to troubleshoot the main board (which has been entirely re-capped) from the original K4600 which stopped working to begin with

If I can figure out what’s wrong with the interface and video board as listed above, then it’s back to figuring out the issue with the main chassis that already got a fresh cap kit. We’ll see, it’s always better to have a working chassis than one for parts, but the latter is pretty useful as well as I’ve learned during this K4600 saga.

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*There are three all original Sidam cabinets (Condor, Asterock, and Explorer) that will not be going on wheels for the moment given they will be staying in my basement for the foreseeable future.