This is a custom PCB that eliminates the high score reset and corruption issues that Q*bert arcade games are known for. If your Qbert high score table resets randomly or becomes corrupted like the image below or the game won’t boot on occasion, this PCB may help you. Also works with any Gottlieb game (Mad Planets, Krull, Three Stooges, etc) that uses PCB part number C-22248-3, C-22248-2 or C-22248-1. (See below for more info on compatibility.)
You can find this reset PCB on ebay here: https://www.ebay.com/itm/113244364384
OR on etsy here: https://www.etsy.com/listing/1190679938/qbert-gottlieb-arcade-high-score-reset
What is it?
This PCB is a very small daughter board that replaces the original Q*bert reset circuit with a much more robust design. It simply “plugs” into the existing holes in the Q*bert PCB.
How do you install it?
Easy! First desolder and remove C25 and R43 from the Q*bert PCB. Make sure the holes circled in the image below are clear of solder. These holes are where the pins of the reset PCB will be inserted. Align the pins of the reset PCB to the holes highlighted and insert carefully. Solder the pins to the Q*bert PCB. That’s it.
Why is the original reset circuit insufficient?
The original Q*bert reset circuit is simply a capacitor attached directly to a logic gate. It is as simple as reset circuit can get. And it works (most of the time). But this basic reset design only delays the reset signal by a fixed amount of time. This delay is designed to give the power supply enough time to stabilize before the reset is disabled. This type of reset circuit does not handle “brown outs” (temporary dips in voltage) or inrush current sags caused by powering on multiple games at once. In addition, inputs to logic gates like the one used in the original Q*bert reset circuit do not like to be driven by a slowly rising voltage. Digital logic gates use voltages of 2.7 to 5v as “logic 1” and 0 to 0.8v as “logic 0”. If the input to a logic gate spends too much time in the “undefined” range of 0.8 to 2.7v the output of the gate can oscillate rapidly (very bad for a reset circuit). This is why the common solution of replacing C25 with a very large cap doesn’t always work. Making C25 larger increases the time the input to the reset logic is “undefined”.
Why is this reset PCB better?
Devices that use a microprocessor generally will have much more complex reset circuits that monitor the input voltage among other things. This PCB follows these common reset practices. Upon power-up the circuit waits until the voltage rises above 4.5v then waits an additional 1 second before it disables the reset. If at any point the board voltage drops to 4.5v or less (like during shutdown or brownout) the reset is immediately enabled preventing corruption of the save data.
Is it compatible with my game?
This reset PCB is compatible with any Gottlieb game that uses video PCB part number C-22248-3, C-22248-2 or C-22248-1. This includes Q*bert, Mad Planets, Krull, Three Stooges, Curveball?, etc. (It is likely compatible with additional video board part numbers. If you have a game with a different part number comment below with a picture of the R43 / C25 area of the board and we can determine if it will work.) The part number of the Gottlieb PCB is found in the lower right corner.
What doesn’t this reset PCB do?
It doesn’t save high scores. You need a working high score backup battery or Dallas RAM. It won’t fix a dead board. (It may help if your board doesn’t boot every time.) It won’t fix power supply issues. (Make sure your Q*bert PCB is getting clean 5v power.)
(PCB color may vary)
Do you want one?
You can find this reset PCB on etsy here: https://www.etsy.com/listing/1190679938/qbert-gottlieb-arcade-high-score-reset
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