Q*Bert always boots to test mode

ChaosJohn

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So I have a Q*Bert that was working for several years and stopped working recently. After trying several simple things (checking fuses, etc), I decided to buy an Arcadeshop switcher kit for Q*bert to replace/rule out the power PCB.

I wired it up and the game booted right up and was playable. (woo hoo).

Then I completed the install by mounting the switcher inside the cabinet and tapping the AC off of the monitor power wires. I turned it on to hear the happy "<knocker> I'm turned on."

The problem is, now it boots directly to test mode and won't go out of it. The select button and "game/test" switch don't seem to have any effect. I unplugged and re-plugged the connector that goes to the test panel, thinking maybe it had come loose and wasn't communicating with the PCB, but no dice.

If I understand what's happening correctly, if the PCB gets NO input from the test switch, it assumes it's in test mode - the circuit has to be closed to put it in game mode. So somewhere between the service panel and the main PCB, the signal is getting lost. Does that sound right?

Could this be a filter board issue? Any idea which of the filter board connectors run to the service panel? (the schematics don't even show an "A8"). Any tips on what else could be causing the disconnect and how to fix it?

thanks a bunch.
 
First and foremost is to check your ground connections. I'd start by leaving everything plugged in and while the game is on check that the test switch is actually working and connected all the way to the pcb. If you change the position of the test switch but you don't see this at the pcb you have id"d the issue and can debug from there. Other way to test this is to bypass the test switch and see if grounding or not grounding the test input has any effect.


Bill
 
The switch has no effect whatsoever.

I did check for continuity in the ground connection to the service panel, and that's fine.
 
Take a jumper wire and jump across the two terminals on the test mode switch. If it goes into game mode then you have a bad switch. On qbert the test switch is normally closed and open for test mode. It may be a cracked solder joint on the filter board causing the issue too.
Im willing to bet you have a bad switch or cracked solder joint on the filter board. Both are common on qberts.
 
Okay, so I put test leads on the switch and tested it both open and closed. It works fine.

So I set the scope on continuity check, fixed one end to one pin of the closed switch, and went fishing in the inputs of the filter board, and found that it goes to the white/yellow wire going into pin 3 on connector A8 J10.

Next I checked the output of the filter board (straight below the input) and that was fine.

Finally, I checked the pin on the connector that connects to the edge of the main PCB. Works great.

So there is no disconnect between the switch and the main PCB (or at least the connector to the PCB.

That leaves 3 possibilities:

1. The ground line that goes OUT from the power (A3-J4 pin 1) is not getting through (though I did check continuity between ground and the switch, and it did seem to be there, so I'm pretty sure it's not this, but I'll double check)

2. the connection between the connector and the edge of the board isn't connecting. Definitely possible. The pin doesn't look corroded or anything, but I'll clean both the pin and the board edge and see if that helps.

3. An actual problem with the PCB.

Now. The first two are testible. If it's a PCB issue, anyone have a clue what on the PCB would force it to always want to go into test mode?
 
" The first two are testible. If it's a PCB issue, anyone have a clue what on the PCB would force it to always want to go into test mode?"

A quick look at the schematics will show you where to look.
Inspect the edge connector and make sure thats good. You could also find out which pin on the pcb edge is for test and pull it low. If the game goes out of test mode than you know its not the pcb.
 
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