{"id":355,"date":"2020-02-08T07:25:02","date_gmt":"2020-02-08T03:25:02","guid":{"rendered":"http:\/\/www.jrtwine.com\/blog\/?p=355"},"modified":"2020-03-02T21:54:44","modified_gmt":"2020-03-02T17:54:44","slug":"43-volt-error-on-a-alltek-systems-replacement-mpu-board","status":"publish","type":"post","link":"https:\/\/jrtwine.com\/blog\/43-volt-error-on-a-alltek-systems-replacement-mpu-board\/","title":{"rendered":"+43 Volt Error on a Alltek Systems Replacement MPU Board"},"content":{"rendered":"

\"\"<\/a>So I was helping another collector in the area try to get a Bally Star Trek<\/strong> Pinball running. It had a Alltek MPU replacement board it in that would start to boot but then stop with 5 diagnostic flashes which indicate a problem with the +43v supply. However, when metered at the test point, the +43v looked grossly normal.<\/p>\n

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

Got in touch with Alltek Systems support and the person suggested disconnecting the sound board and seeing what happened. The game came up with it disconnected, and the support person said there was something wrong with the +43v stuff on the sound board. Right where it comes in there is a diode (CR3) that the collector tested open one way, and about 94k ohms the other.<\/p>\n

So a good diagnostic step for this kind of hardware, perhaps even with the original boards in it, is to completely disconnect the sound board and see if the behavior of the game changes.<\/p>\n

Update<\/strong>: when I returned to that collector’s house, we lifted one end of the diode and tested it again.\u00a0 Tested open one way but with a lower-than-expected forward voltage drop of about .350v where we expected more for a standard 1N4004 diode.\u00a0 I called it bad and pulled the diode.\u00a0 Had the collector solder in a replacement and the Star Trek came right up!<\/p>\n","protected":false},"excerpt":{"rendered":"

So I was helping another collector in the area try to get a Bally Star Trek Pinball running. It had a Alltek MPU replacement board it in that would start to boot but then stop with 5 diagnostic flashes which indicate a problem with the +43v supply. However, when metered at the test point, the […]<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[3,10,7],"tags":[],"class_list":["post-355","post","type-post","status-publish","format-standard","hentry","category-repair-logs","category-ballymidway","category-repair-logs-2"],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t