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Catzoo

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Hi,

I just did a full recap on my Blast City (Audio amp & PSU) because i was having issue to go to 5V with systems like CPS2.

The recap seem to be ok, as everything booted up as normal, no smoke or anything. I can now reach 5V with CPS2 (still needs to crank the 5V pot to the max, but at least i'm ok)

BUT, as soon as i touched the glass of the screen, it seem to put parasite on it. I tried again (being a bit scared to be honest), and i manage to make the screen shift for a small moment when touching. I don't know anything about high voltage, but this looks like a grounding issue ?

I can also do it this way : if i touch the bolt (going to the metal frame of the screen i guess ?), it still does it. I don't know how dangerous it is for me or the cab, but i want to understand what's causing it. I'm pretty sure i would have notice that before the recap, as obviously touched the screen or surrounding metal part before, and nothing like that happened.

A few things to note :

- The cab is not grounded. There's nothing on the ground screw at the back, and the cable i had with it has 3 probe on the cab end, but only two on the outlet that goes into my 110/220 transformer. Again, i have the exact the same setup on my Astro city and never noticed something like this, and even on this blast i'm pretty sure the issue wasn't here before.

- The monitor had been replaced with a Sanwa PFX, but everything looked shady about it. I had to redo the RGB plug (JST JH on the side) because the pins were poorly made, and the main voltage going to the screen had leads poorly made together, again i had to put electrical tape because the wires were nearly touching ...

Knowing all this, what should i do ? Can i use my multimeter to check on something ? Should i try to ground the cab first ? Should i ground the screen frame to the ground pins at the back of the cab ? (or should i do this but only after grounding the whole cab ?)

I'm really lost at this point, and i would like to keep my cab and myself alive, i don't even know if it's safe to use the cab ?

Thank you for your help !


 

nem

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Ground your cab. Blast is easy, you just need a 3-pin power lead.

You should ground your Astro too. If the two cabs are next to each other, take some wire, put fork terminals on both ends and connect them to the ground posts on both cabs.
 

Catzoo

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Thanks @nem for your answer. I had already ordered 3 pins main power cable, and i just got them in the mail today.

It seem to fix the issue with the glass, but i can still shift the screen by touching that black screw on the panel.

I tried to check the Blast city manual, but i don't really get how to read this.

I should also note that the screen OSD also seem to have parasites when shown on screen, so maybe the issue was there since i got the cab and me opening the PSU had nothing to do with it.

Anyway, here's what i found :

- The screw at the bottom center of the cabinet (field ground ?) that has all green wires have continuity to the earth pin of the main outlet plug.

- CRT metal frame have connectivity to PIN 14 of the jamma edge

- CRT Metal frame doesn't have continuity to the pin 1 of the jamma edge


I noticed that the coin door have two green ground wire, and one is long enough to reach the CRT frame. So maybe it was suppose to go there ? But if i do that, ALL ground are connected, even the 1 from jamma edge, which from what i understood is bad ?

Anyway i'm a bit lost here and way over my knowledge, so if someone knows better, i'll be happy to get some help :)

Thanks !
 

Catzoo

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EDIT : the issue seem to be fixed. I've tried simply grounding the metal frame to the field ground. Everything was connected to earth (central screw of the cab, metal parts, screen frame and video ground pin 14, and also pin 1 when a pcb is plugged in that link 1 and 14), and all of this connected to the earth probe of the plug.

I now can't make the screen shift by touching that bolt, so i guess i'm good !
(the OSD seem to be still shaking like before, but it's not a big issue, and is maybe an issue with the screen itself)
 
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