P2 start button always on

Arcade cabinet hardware and accessories
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philbee
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Joined: August 18th, 2008, 11:51 pm
Location: midlands(ish) Ireland

P2 start button always on

Post by philbee »

Hello everyone,
Looking for some advice with this. I have a naomi universal and the p2 start button is permanently on. I've checked the wiring and the switch is perfect and everything is fine back to the board. In the test menu it just shows as on the whole time.
Any advice or help is appreciated. Picture of the board attached.
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RMRM
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Location: Portugal

Re: P2 start button always on

Post by RMRM »

Those 8 smal chips on the picture (16 legs, i can't remember the reference now) are responsible for the inputs.

I've repaired 3 of these boards in the past with the same problem. Get the schematic, see which pin (on the connector) is the "P2 start" and follow the trace to the correspondent chip. Replace it as they are very cheap.

Edit - If you have a logic probe, you can also check it like this:
The pin must be "low" when not pressed and "high" when pressed. If it is always "high", i'm almost sure it's one of those chips that are faulty. I think they work like optocoupler, but i have no background in electronics, i'm just a curious guy trying to help.
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philbee
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Re: P2 start button always on

Post by philbee »

That's great info, I will check it out. I've donated the machine to a museum about 40 miles away from me so I won't be able to get near it until Friday or next week but I will look at my net city and see if I can get a reference number for the chips.
Thanks for the advice it's much appreciated.
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RMRM
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Re: P2 start button always on

Post by RMRM »

If it's easier for you, i can also check the chip reference when i'm at home later tonight, i think i still have a couple spares left.
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philbee
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Re: P2 start button always on

Post by philbee »

I've attached a close up picture of the opto coupler.
Ali express has them but if you could spare one of your spares for me it would be great?
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RMRM
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Re: P2 start button always on

Post by RMRM »

I can search them (i think i know where i put them...) but i'm afraid the shipping cost from Portugal might cost more than ordering a couple from Ali or Ebay with free shipping.

Let me check
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philbee
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Re: P2 start button always on

Post by philbee »

Sorry for not getting back about this sooner. I got the opto couplers from Ali express and used a multi meter + the otaku wiki to trace the one that needed replacing. I removed the old coupler and fitted the replacement and all is working well now. Thanks RMRM for the advice.
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