{"id":2134,"date":"2013-04-01T15:30:33","date_gmt":"2013-04-01T13:30:33","guid":{"rendered":"http:\/\/www.retro.co.za\/blog\/?p=2134"},"modified":"2013-04-02T10:52:04","modified_gmt":"2013-04-02T08:52:04","slug":"haunted-house","status":"publish","type":"post","link":"http:\/\/www.retro.co.za\/blog\/?p=2134","title":{"rendered":"Haunted House"},"content":{"rendered":"

No, not the one we live in, but my pinball machine<\/a>.<\/p>\n

The upchucker<\/a> and the 5-bank reset were not working, and the replacements have been sitting around for a while, waiting for a rainy day. Well, today was that day.<\/p>\n

Replaced the upchucker coil with an A-4895 as per Clay’s notes*<\/a> (the manual calls for an A-5194) and the fuse with a 2.5A slow-blow (again, Clay’s recommendation) and it worked about three times before the relay arc’ed and the fuse popped. I might need the pop bumper driver board modification<\/a>, but I’ve been thinking about it and I don’t think it’s necessary.<\/p>\n

\"\"<\/a><\/p>\n

SW31 tells the CPU that there’s a ball to be up-kicked, and the CPU then pulses the K relay once which kicks the ball… once. This is what the pop bumper driver board also does, except using a one-shot (74121 originally, 4538 in the Rottendog replacement) and not a CPU (well, except for the www.homepin.com solution<\/a>, which uses a PIC).<\/p>\n

My problem is that the K relay is failing, and replacing that with a modern transistor should do the job. This seems to be what’s happening here<\/a>, as far as I can tell that’s a PNP\/NPN pair driving the coil, the capacitor provides extra oomph locally, with the oomph held locally by the big-arse diode. It might be a hack, but I think it’s a good<\/em> hack.<\/p>\n

I also replaced the 5-bank reset solenoid, no joy. Clay (again) notes that the transistor is very likely to fail, so I replaced it with an MJ2955 I had kicking around and all is well.<\/p>\n

\"\"<\/a><\/p>\n

Under playfield transistor on right hand side of lower playfield — this transistor is driven by a lamp (low current) output and drives the 5-bank reset coil.<\/p>\n

* Which I downloaded way back before he went commercial. Seems one has to pay for them these days. I would. They’re really good.<\/p>\n

http:\/\/www.homepin.com\/gott.html<\/a><\/div>\n

No, not the one we live in, but my pinball machine. The upchucker and the 5-bank reset were not working, and the replacements have been sitting around for a while, waiting for a rainy day. Well, today was that day. Replaced the upchucker coil with an A-4895 as per Clay’s notes* (the manual calls for an A-5194) and the fuse with a 2.5A slow-blow (again, Clay’s recommendation) and it worked about three times before the relay arc’ed and the fuse popped. I might need the pop bumper driver board modification, but I’ve been thinking about it and I don’t think...<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[65],"tags":[],"class_list":["post-2134","post","type-post","status-publish","format-standard","hentry","category-pinball"],"_links":{"self":[{"href":"http:\/\/www.retro.co.za\/blog\/index.php?rest_route=\/wp\/v2\/posts\/2134","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/www.retro.co.za\/blog\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/www.retro.co.za\/blog\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/www.retro.co.za\/blog\/index.php?rest_route=\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"http:\/\/www.retro.co.za\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=2134"}],"version-history":[{"count":7,"href":"http:\/\/www.retro.co.za\/blog\/index.php?rest_route=\/wp\/v2\/posts\/2134\/revisions"}],"predecessor-version":[{"id":2143,"href":"http:\/\/www.retro.co.za\/blog\/index.php?rest_route=\/wp\/v2\/posts\/2134\/revisions\/2143"}],"wp:attachment":[{"href":"http:\/\/www.retro.co.za\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=2134"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/www.retro.co.za\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=2134"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/www.retro.co.za\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=2134"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}