9999 Damage
Grand Master
Putting this in general since the nature of the problem is probably not Sega-specific.
tl;dr: I have a short. I can't find a solder bridge and I want to know if anyone knows of other common sources of short circuits.
My Astro PSU's +5V line was topping out at ~4.5V. I've heard a couple times that 400-5198s are overdue for a recap, so I figured it's time. Unsurprisingly, several caps were leaking. I removed the old caps, washed off grime with distilled water and IPA, then (once dry) replaced the caps and tested for continuity. RUH-ROH. There's a short circuit between +5V and G on the 9-pin output. Every solder joint in the red area below has continuity, with resistance around 46 Ohm between circuits.
Okay, so... I'm not looking for anyone else to squint and find the bridge that I didn't. I've been over this board for two nights, solder-side and component-side, and I don't see it. I removed the new caps, I checked the fuse (no obvious scorches), I IPA'd off the no-clean, I cleaned off every little fiber I could find, and I reflowed old solder joints that looked suspiciously close to another circuit. I'm still mapping resistance differences to try to localize the short. For my trouble so far, one of these circuits (the big island of green amid the red) is no longer part of the short circuit. The PSU was (mostly) working before I pulled it, so I don't think the trapped grime is the cause unless maybe the wash concentrated it.
What I am asking is:
tl;dr: I have a short. I can't find a solder bridge and I want to know if anyone knows of other common sources of short circuits.
My Astro PSU's +5V line was topping out at ~4.5V. I've heard a couple times that 400-5198s are overdue for a recap, so I figured it's time. Unsurprisingly, several caps were leaking. I removed the old caps, washed off grime with distilled water and IPA, then (once dry) replaced the caps and tested for continuity. RUH-ROH. There's a short circuit between +5V and G on the 9-pin output. Every solder joint in the red area below has continuity, with resistance around 46 Ohm between circuits.
Okay, so... I'm not looking for anyone else to squint and find the bridge that I didn't. I've been over this board for two nights, solder-side and component-side, and I don't see it. I removed the new caps, I checked the fuse (no obvious scorches), I IPA'd off the no-clean, I cleaned off every little fiber I could find, and I reflowed old solder joints that looked suspiciously close to another circuit. I'm still mapping resistance differences to try to localize the short. For my trouble so far, one of these circuits (the big island of green amid the red) is no longer part of the short circuit. The PSU was (mostly) working before I pulled it, so I don't think the trapped grime is the cause unless maybe the wash concentrated it.
What I am asking is:
- Are there other sources of short circuits I should look for? Degraded components? The many scuffs in the solder-side solder mask?
- What is the big yellow component labeled 210100, and which of its pins are supposed to be on G or +5V? Wondering if I have detritus bridging the pins on the component side.
" pointing toward the pot, or maybe an ugly 13t or 13+.