Amiga 2500 Mouse PotY, PotX problem

[JimS]

The fuse was added at Rev 6 motherboards. That looks like a 4.5. So, it could be a blown trace, if there's no 5v at the joystick port.

[JimS]

save2600 wrote:
And a blown trace could have happened because of battery acid leakage you're thinking JimS?  Or sloppy techs dropping their screwdrivers on the mobo too I guess. lol  

Possible... but I was thinking more like the trace acted as a fuse and vaporized. I've seen it happen on some machines that came in for repair. That's why they added the fuse, both to the joystick ports and the external video port as well.

[JimS]

In the little gems department, I once saw a 2000 where the mouse failed every time I tightened down the screw next to mouseport. Never did figure that one out... finally just put a plastic washer under the screwhead.

[JimS]

amigaksi wrote:
I think I vaporized something on my A500 long time ago by pluggin in a Mimetics genlock into the computer while Amiga was on.  The genlock died instantly but Amiga 500 still works great but it no longer works with A520.  The monochrome video out still works.  Any picture of where that fuse is on video port on A500?

I don't see any fuses on the 500 schematics. But it does sound like you've fried a trace. Check pins 21 (-12v), 22 (12v), and 23 (5v). If you can't see the open trace, you can use 30ga wire to tap the proper voltage from somewhere else on the board. I'd consider soldering in one of those fuses just in case.

[JimS]

save2600 wrote:
ROTFLMAO! Maybe you had an Amiga 2000 'especial' where someone from South America douched down the mobo with WD-40   ;-)    LOL!

Well... I don't know about that... at least it wasn't duct tape. ;-)
But I have seen a few strange failures. Like a bad CIA missing one bit to the printer port. So every time a character with that bit on printed, it came out wrong... but other characters printed fine. Or my own 1000 that had a stuck RTC in it's CIA chip. The system time would run for about 10 seconds then jump back groundhog day style and restart. Kinda useful for hack lite that was seeded off the RTC. There were only a few starting positions, and once you memorized them.... ;-)
I once had a similar problem on the mainframe I used to repair. It's backup RTC counter was broken and was basically running at about 4 times real time. We had to switch to the backup for other problems and nobody noticed the glitch until the system's clock thought it was the next day. They decided to stop all work until the world caught up with the computer. ;-)