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Taito B System 180VCU blown pins

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GF77

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Hi there,

the other day my Ashura Blaster was running when suddenly something popped. I actually witnessed how a spark blew off that pin and trace directed to the cap and with it that trace right next to it as well. The third pin doesn't seem to be happy either. I have a non functioning Nastar as donor but before even attemting to exchange that chip and getting greeted with another spark, Is this a known problem? Why did this pin blow up? Maybe that cap is faulty? But can a ceramic cap go even wrong? Or maybe I had the voltage set to high?




20250630_162849.jpg
 
looking up schematics (Nastar Warrior Schematics are available and includes this chip).
unsurprisingly Pin 18 is Vcc and Pin 19 is GND.
Pin 20 is a data pin labeled "/FWE0" and I think it's maybe just collateral damage. I'd suspect that maybe before this blew up these pins were maybe bent and shorted together. if this were an internal short I'd suspect a hole burned in the chip itself not the pins burning up.

BUT you can check continuity across these pins to see if they are reporting a short.

if it all checks out ok I'd try just repairing the pins, worst case you're right back where you started.
 
Last edited:
Thank you very much! I just measured no short between pin 18 and 19, just 115 Ohms. No short between 18/19 and 20 either.

So in theory I could just solder everything correct in place again and then it should work. I'll give it a try these days:)
 
GF77 said:
So in theory I could just solder everything correct in place again and then it should work. I'll give it a try these days
Click to expand...
I'd give that a try, it looks like the Vcc trace is burned up so you'll probably want to jump that pin directly to the cap. after the repair all 3 pins, make sure both Vcc and GND have good continuity and low resistance back to the JAMMA edge pin, and of course no shorts to each other. Might also want to double check pins 17 and 21 just for good measure.
 
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