1942 Capcom help needed please

blackben123

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Installed a 1942 board in a Midway CT and something isn't right. Player 1 - everything works as it should. Player 2 - the plane moves from its center to far left and stays there. I have no L/R control on the stick and can only move Up. Then when I center the control my plane drops to the bottom of the screen.

Also...the gun is constantly firing. In diagnostics - I/O shows me 3 closed switches for Player 2. I've buzzed out the entire edge connector and it's good.

Spent many hours verifying the wiring isn't shorted and confirmed no closed switches. I'm starting to think I have a board problem but where do I start?

Anyone encounter something like this before? Someone have a schematic?

Thanks for any pointers I may have missed.
Ben
 
did you try switching player 1 and player 2 wires in the edge connector to see if it stays a player 2 problem?

I considered doing that but was hoping I wouldn't need to. Heres what I did....

Checked continuity on all the + wires from the connector to each P2 switch, got a similar resistance on all of them.

Then between P2 Gd to each switch(at the connector) and activated the switch. All switches closed and stayed opened as they should.

I further checked by ohming every combination of relative P2 wires. Nothing is shorting.

Could be dead wrong here - but I'm still thinking the wiring is good. I used the pin-out chart in the 1942 manual and assume it's correct, the only wiring I added (originally a Universal Mr. Do) were "Roll" buttons which I ran with their own Grds. BTW this works on P2.

Okay...the player swap would be a lot of soldering/desoldering and I'd have to do it twice
whether I find the prob or not. How about this plan...."insulate" all the P2 edge connectors with scotch tape to all relevant switches then slip the connector on.
If the P2 problem continues that should 100% eliminate the wiring and I've got a real headache then.
Am I pissing in the wind with this plan ?

And thank you guys for the input.
Ben
 
Does your CT have microswitches of leaf switches? Are they shorted? Have you disconnected the joystick wiring for p2 and check the test screen?
 
1942 ???

I thought 1942 was one player (alternating)? Did you mean you have a 1943 game?? If so, I may have a schematic sitting around.....
 
Player 2 chip (1943)

If it is 1943 bd, check chip 8B(245 chip) on the main board pins 11,12,13,14 or the RC5 part.....
 
Well, I did the scotch tape deal on all 6 of the P2 pads at the PCB and guess what....the problem continues. I'm 100% convinced at this point its the board. Wishing someone would confirm if this approach is conclusive enough....

Rampart
Thanks for your response. I think you're going in the right direction here but is 1943 the same architecture as the 1942 board? I'm not sure what RC5 is and as for checking the 245 chip-what logic states should I see - all lows? Or am I just checking for continuity or ???

Thank you to all for your tips and ideas - I think we're going to hunt the offender down if you just bear with me and keep the info flowin

Ben
 
Blackben,

OK, I just got back online.... My original question is this... In the 1942 game one player plays at a time. In the 1943 game two player play side by side(thus needing a 'player 2'). I did not know the original 1942 had 'two players' (although I am not an expert on this).

Second, on the 1943 board, the RC5 is a type of res/cap circuit(I think) near the '245' chip. It should be labled on the board. I will do some checking on my board tonight and give you more info, but logically speaking your 'switch' takes the signal from the board to ground, so I would think it should be 'high'. If your chip is bad, it may be shorting to ground and tricking the CPU to think that a button or switch has been has been pushed.

I hope this helps...... More later tonight or tomorrow morning (depending how good the Playoff game is tonight :)).
 
Whenever you have an input problem on the board, follow these steps:

Check for shorted wiring.

Check for stuck switches.

Check for +5v at the board edge connector on the offending control line. The lines are tied high through a resistor pack (or resistor/cap/transistor pack on some boards such as Capcom). If that pack is bad then the board won't read a high to low logic transition when the switch is pressed or control stick is moved.

Check for ground at the board edge connector on the offending control line WHEN THE BUTTON IS PUSHED OR STICK MOVED. If it never goes from +5 to ground then you probably have a bad switch or open wire in the harness.

If you have a ground at the edge connector on the offending control line when the button isn't pushed and you've verified wiring and the switch is good then replace the chip that the control line leads to. It probably has a short on the input.

Don't forget the obvious: look for corroded traces where the trace meets the edge connector, check for broken components, and the obvious gouged or scratched traces.

RJ
 
Good input!

Blackben I want to apologize for not knowing about a 1942 game with two players (same time). I did some digging and found a pinout for an alternate 1942 game with a board pinouts of 12,13, P, and R being for player 2 plane direction (ooops). Sorry about the confusion (I learning too :)).

After more digging, I even located a 1942 top half in my own collection and metered out the main chip. Assuming it is the same board as mine, the possible bad chip is located at 5A on your top board. It is a line buffer, 74HC367. This is a CMOS device which can be easily damaged. Interesting thing is that my board even had three of them socketed already, so if you're lucky you may have an easy repair (if it is the chip and already socketed).

I can't find the actual schematics for the 1942, so I hope this helps. Let me know if you need more explaination on any terms that I have used.......

Good Luck!
 
Thank you all the helpful direction guys, I just got back and I'm ready to do another shift on the bastard.

Rampart you're right of course; 1942 is a 1P game but the board allows for alternate second player controls labeled P2 to run in a cocktail table (along with a screen flip option on the dipswitchs) Sorry for the confusion haha ! But you did motivate me to pull the board and start looking at chip numbers. I have two 245's but they seem more related to the dipswitchs than P2 inputs.....

Channelmanic, thats a very inclusive checklist and I give you a big thumbs-up for it. Man..you covered the whole gamut and then some, thanks for explaining it all.

OK..I'm a little confused on the part about the "resistor/condenser/" (these are labeled RA on this board-I'm assuming "resister array") and how to test it. If I've got +5 at each P2 switch input does it confirm this component is good and the problem is elsewhere? Having no schematics makes it kinda tough to chase the flow on this board but the P2 inputs seem to all go to M74LS367AP-the first chip that Channelmanic refers to.

Can I sub a HD74LS367AP - in a socket naturally - even if just for a quick test and then swap back if no fix?

Ben
 
Good input!

Blackben I want to apologize for not knowing about a 1942 game with two players (same time). I did some digging and found a pinout for an alternate 1942 game with a board pinouts of 12,13, P, and R being for player 2 plane direction (ooops). Sorry about the confusion (I learning too :)).

After more digging, I even located a 1942 top half in my own collection and metered out the main chip. Assuming it is the same board as mine, the possible bad chip is located at 5A on your top board. It is a line buffer, 74HC367. This is a CMOS device which can be easily damaged. Interesting thing is that my board even had three of them socketed already, so if you're lucky you may have an easy repair (if it is the chip and already socketed).

I can't find the actual schematics for the 1942, so I hope this helps. Let me know if you need more explaination on any terms that I have used.......

Good Luck!

Sorry I didn't see your new post as I was busy typing mine and yes that is the same chip location that I'm looking at - directly in line with the P2 inputs.

Not so lucky here - no socket, but it gets one tomorrow. Thanks lots for checking your board for me and the chip info.
Ben
 
The long answer:

The important part is "74LS367"... the MC, HD, M, and other numbers in front are ones that help identify the manufacturer. Ones after it help ID the package style (plastic dip, ceramic, surface mount, temperature range, etc) and other things specific to the manufacturer.

The short answer:

Yes. You can sub it.
 
The long answer:

The important part is "74LS367"... the MC, HD, M, and other numbers in front are ones that help identify the manufacturer. Ones after it help ID the package style (plastic dip, ceramic, surface mount, temperature range, etc) and other things specific to the manufacturer.

The short answer:

Yes. You can sub it.

I like the long answer, learned something there(the old "teach a man to fish" analogy) Thanks..

Just one more question. Rampart said he has a replaced CMOS version on his board, mines a TTL original. Any advantage with a CMOS version vs TTL in this case?

Ben
 
In general, do NOT use an HC to replace an LS part. They operate at different logic levels and the results could be unpredictable.

However, for this case, it should work fine since the two logic levels for this case are full 5v and ground. If you were driving it with other logic chips instead of a 5v tie through a resistor and a ground through a switch then you may have unpredictable results.

74HCT chips would work... the T is for TTL logic levels.
 
In general, do NOT use an HC to replace an LS part. They operate at different logic levels and the results could be unpredictable.

However, for this case, it should work fine since the two logic levels for this case are full 5v and ground. If you were driving it with other logic chips instead of a 5v tie through a resistor and a ground through a switch then you may have unpredictable results.

74HCT chips would work... the T is for TTL logic levels.

Thanks for the info. I'll post the outcome after I install a new chip...

Ben
 
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