QBert JROK Board - Board Keeps Resetting in Play

SalParadise

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Been a bit, but I'm trying to figure this out. This is a problem that just started.

I have an all-original Qbert - fully working with all original boards and power supply. Filter board was upgraded to the Arcade Shop. Power supply rebuilt two years ago.

Switched to JROK board for more variety. Original PCB still in place.

JROK board starting to reset when knocker went off. Checked knocker diode and knocker, OK. Replaced it with a new one just in case. That's OK too.

Now, when the board changes to another board (you finish a board) it resets. Sometimes resets when knocker goes off but not all the time.

I'm baffled because I have had this board for two years in this setup and it's been fine. Now it's unplayable - and I'm bummed. Any ideas?
 
As somebody who spent 9 YEARS tracking down a similar problem with a Q*Bert (mine is stock, not JROK), I would strongly suggest that you start by checking your connections.

I had a very similar issue: random resets and associated with knocking.

Ultimately I did two things that seem to have fixed the issue:
(1) I tightened up the large edge connector at the main logic board. I found that if the game was running and I wiggled the edge connector (and narrowed it down to the striped grey cable that runs from the back side of the edge connector on the logic board (5th wire from the left) to A8P7 (pin 4) on the filer board) then the game would knock. If I remember right that's a ground cable. In any event, making sure the wire connected well to the harness and then gently bending in the harness connector to make good contact with the edge connector on the logic board resolved the loose connection issue. This helped improve the knocking situation but I was still having some issues with knocking and resets.

(2) The next thing I did was to replace the header and connectors at A8P1 on the filter board (lower right corner). This had been previously replaced but its obvious that this particular connector gets a lot of heat. I ended up installing one of those black headers that's designed for high heat and then used a Molex housing with Trifurcon pins for the connector instead of using the factory-style IDC connections. Clive at Coin-Op Cauldron advised me to do this with some similar connections on a Williams Pinball machine so I figured I'd try the same with Q-Bert since it uses the same style of IDC connectors that pinball machines use.

Your milage may vary, but there are so many connectors in Q*Bert and wiggling wires and connections is a really easy thing to do.


If the problem is with the JROK board then none of this may be helpful.
 
Probably power.
OG boards draw more power so power supply is tweaked high on the +5V (due to higher load current and voltage drops).
JROK draws almost no +5V power, so probably is seeing higher than recommended +5.0V on its pins/ICs.
 
Jrok boards are especially sensitive to power. The 5V has to be *spot on* 5.00V. I would start by measuring and adjusting if needed.

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