Star Trek
Bally, 1979You're currently viewing posts by Pinsider barakandl.
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E11 to E25 would be setting the board to trigger U2 Pin 20 off of /A14. Is that for 2532 and similar type of masked PROM?? I have seen that jumper done many times, but not really sure why they use it as I would normally always convert right over to the typical 2732 jumper setup we use.
The standard jumpers for 2732 have u2 of triggering with /(vua+q2+a12)+A11.
Quoted from JethroP:I'm not sure what you are suggesting. Remove the jumper? Or it will work?
It depends if your ROMs are proper. Considering ive seen countless MPUs with that jumper setup, it will work in some situation.
If you are locked up and unsure / know about your roms/jumpers are mixed up/good. Then you rejumper the board for two 2732s and get new known good 2732 ROMs.
Quoted from JethroP:Ive made some progress. I missed this the first time around. There was slight corrosion damage that I cleaned up but missed repairing a broken trace and disconnected capacitor near the 555 chip. Now it resets and all is working EXCEPT I keep blowing the fuse under the playfield. When I start a game one of the pop bumpers chatters for a few seconds then the fuse blows. I've checked the resistance across the coil and it's like the others, about 10 ohms. I've checked the switch and it's about 1/16" like the others. Now what??
When the 555 timer had an issue you where probably hammering the CPU with display interrupts and the software would crash.
Find the pop bumper under the PF and clip off the capacitor wired across the switch. If that fixes it the cap was bad. The cap helps the switch be more sensitive, but I have found a properly adjusted pop bumper can be nice and snappy without that cap. If it seems to be missing closures and you don't like the performance add the cap back. 0.047uF (or 47nF)
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Gilbert, AZ