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.
P2 start button always on
- philbee
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- Location: midlands(ish) Ireland
P2 start button always on
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- RMRM
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- Location: Portugal
Re: P2 start button always on
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.
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.
- philbee
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Re: P2 start button always on
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.
Thanks for the advice it's much appreciated.
- RMRM
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- Joined: April 20th, 2013, 4:45 pm
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Re: P2 start button always on
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.
- philbee
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Re: P2 start button always on
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?
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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- Location: Portugal
Re: P2 start button always on
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
Let me check
- philbee
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Re: P2 start button always on
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.