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Point Blank gun issues

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Player Quote  Post ReplyReply Direct Link To This Post Posted: 03 Jul 2020 at 9:29pm
Ok so before i start to haul this lump out, can anyone confirm if it's compatible please? It's defo not like the monitor in PB and this has a beast of a PSU that powers it. 





Thanks in advance.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote SUPERSPRINT Quote  Post ReplyReply Direct Link To This Post Posted: 03 Jul 2020 at 9:42pm
What are your voltages at the gun position pcb?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote gunblade Quote  Post ReplyReply Direct Link To This Post Posted: 03 Jul 2020 at 10:09pm
not compatible, its a mtc9110
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Player Quote  Post ReplyReply Direct Link To This Post Posted: 04 Jul 2020 at 8:11am
Originally posted by SUPERSPRINT SUPERSPRINT wrote:

What are your voltages at the gun position pcb?


Erm not sure where that is. The plug that goes to the gun there is 5v. It was slightly under so I turned it up a notch. Are you talking about the pcb (I assume) in the gun?? From what I can see the gun wiring goes straight to board. Could this board you mention be in the tin box with the main board?



Cheers

John


Edited by Player - 04 Jul 2020 at 8:19am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Player Quote  Post ReplyReply Direct Link To This Post Posted: 06 Jul 2020 at 10:49pm
Bump :)

Looking at the manual the position PCB what the guns are connected to. Can anyone tell me how the sensor works as in what should be going to the gun? I put a logic probe on TRG1 and 2 and it just said high. I thought maybe there would be a pulse, I really have no idea as guessing.

If I can't sort i'll have to sell it for scrap and that will cause me great sadness :(


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Post Options Post Options   Thanks (1) Thanks(1)   Quote Velyks Quote  Post ReplyReply Direct Link To This Post Posted: 06 Jul 2020 at 11:43pm
Namco guns work by cathode ray timing, so the guns are wired up to a Position PCB inside the cage which does all the fancy bits with working out where you shot.

When you pull the trigger the screen flashes white and the gun sensor sends a signal to the position PCB when the phosphor its looking at lights up. The position pcb times how long this takes from the start of a frame using the composite sync signal, it can then work out where on the screen you're pointing since it knows how far the scanning electron beam would have travelled in that time.

If your guns not tracking it's either a problem with:
- The gun sensor not being able to clearly see the phosphor (low brightness, something obstructing the view, dirty sensor).
- The position pcb not being able to read the gun sensor.
- The position pcb not getting a good csync signal
- The position pcb not being able to talk to the game pcb.

A dodgy csync seems fairly likely to me if changing the brightness doesn't help. Get the scope out and check that the csync input pin on the position pcb is getting a good signal. You can see where that is on the diagram in this manual. https://www.gamesdatabase.org/Media/SYSTEM/Arcade//Manual/formated/Point_Blank_-_1994_-_Namco.pdf
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