Jeremy Popp Posted October 10, 2014 Share Posted October 10, 2014 I'm looking for help repairing a bad/failed Buck Rogers TI-99/4a Cartridge. I can solder and have a multi-meter, but still an amateur when it comes to this stuff. Cart will not load, shows blank screen and typically loud beeeeeeep noise that goes on forever. It was free to me courtesy of Cschneider (thanks again!) when buying another cart. It has been tested on multiple functioning TI units. I followed continuity from the tip of the cart all over the place with no breaks, it's also been cleaned a lot. Is there a diagram that tells me what everything on the board is? I know the bottom right thing is a resistor, but no clue on the rest. Is there a typical failing part for bad cartridges? Thanks for any help! Jeremy Quote Link to comment Share on other sites More sharing options...
+Ksarul Posted October 10, 2014 Share Posted October 10, 2014 I'd make sure none of the diodes is shorted--and that the big cap in the middle is still good. The two smaller chips are GROM chips specific to the cart (part of the program is in them), and the big chip is the ROM. If there is a problem with either of the two small chips, you cannot get a replacement for them. You could burn a new chip of the ROM though. I'd put the most likely failure as one of the diodes or the capacitor though, as either of them will give the symptom you describe. Quote Link to comment Share on other sites More sharing options...
Jeremy Popp Posted October 10, 2014 Author Share Posted October 10, 2014 Thanks, so the Diodes are the small things with gold end caps? I'll check the capacitor also, I've never seen one that looks like that, hopefully I can find an easy replacement. Thanks a lot for the info. Quote Link to comment Share on other sites More sharing options...
+Ksarul Posted October 10, 2014 Share Posted October 10, 2014 The diodes are probably a variety of the 1N914. You can get them at Radio Shack--but they won't be the glass type (which is OK). Quote Link to comment Share on other sites More sharing options...
Imperious Posted October 11, 2014 Share Posted October 11, 2014 You can still use a normal electrolytic capacitor, You just have to bend one of the legs all the way back over to the hole on the other side. Use heat shrink if You want for extra protection. Quote Link to comment Share on other sites More sharing options...
Jeremy Popp Posted October 11, 2014 Author Share Posted October 11, 2014 Thanks for more replies and ideas. This morning I verified the diods get 0.530 one direction and 0 the other. The resister is verified within spec 100 +/- 5%, and I replaced the capacitor with a 22uf 35v (original is 22uf 25v) with no change. So it's probably the ROM or GROM chips and I don't have the ability to recreate/repair these (that i know of). Unless someone has other ideas, I'm going to offer it free to someone, just pay shipping - includes the shell/case which is white, and nice condition. $2.50 paypal should cover it, PM for details. Thanks. Quote Link to comment Share on other sites More sharing options...
+Ksarul Posted October 11, 2014 Share Posted October 11, 2014 Are you going to Chicago this year? There are lots of reuse opportunites for empty cartridge cases (for that matter, you can buy one of the 512K cartridge boards and an EPROM and fill it with one of the new multicart images). There are lots of use cases for an empty cart case these days--and we even make nice labels for them. . . Quote Link to comment Share on other sites More sharing options...
Jeremy Popp Posted October 11, 2014 Author Share Posted October 11, 2014 I don't think I'll be in Chicago (is there a TI convention?). I mostly play retro console games, but dabble a bit in TI stuff. Thanks for heads up on other uses, I'll look into it. Quote Link to comment Share on other sites More sharing options...
+Ksarul Posted October 11, 2014 Share Posted October 11, 2014 There is a TI convention every year at the beginning of November in Evanston (right outside of Chicago). This year it is on 1 Nov. and they are always a lot of fun. Quote Link to comment Share on other sites More sharing options...
+Lee Stewart Posted October 12, 2014 Share Posted October 12, 2014 I don't think I'll be in Chicago (is there a TI convention?). I mostly play retro console games, but dabble a bit in TI stuff. Thanks for heads up on other uses, I'll look into it. Hey, I'll be driving 700 miles to get there. You're just 300. Like Jim said, it's a lot of fun. ...lee Quote Link to comment Share on other sites More sharing options...
Gazoo Posted October 12, 2014 Share Posted October 12, 2014 Hey, I'll be driving 700 miles to get there. You're just 300. Like Jim said, it's a lot of fun. ...lee 737 miles for me. Gazoo Quote Link to comment Share on other sites More sharing options...
+Lee Stewart Posted October 12, 2014 Share Posted October 12, 2014 737 miles for me. Gazoo I rounded up. I'm 15 miles south of G'burg—so 673. See ya there! ...lee Quote Link to comment Share on other sites More sharing options...
RXB Posted October 12, 2014 Share Posted October 12, 2014 From the West Coast to Chicago would be a hell of a drive for me. Quote Link to comment Share on other sites More sharing options...
+OLD CS1 Posted October 12, 2014 Share Posted October 12, 2014 Which is why I am flying 977 miles. Quote Link to comment Share on other sites More sharing options...
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