|Posted by: AceBHound on Mar 20th, 2011 10:49 AM|
|I've been working on a number of things the last few weeks, nothing of substantial interest but some research & purchases that will lead up to some neater future projects and that's always a good thing =]
I fixed one of the non-working SB-100 sound boards after replacing the LM324N voltage follower & also the LM380 power amplifiers. I'd imagine this was the board in the Hot Hand when a harness on the rectifier board was accidentally plugged in backwards and caused 43v to go down the 12v circuit. The LM380s run off of 12v.
I have another Stern MPU board that's acting very flaky and has been giving me a good run for the money. Battery corrosion was cleaned up on the board late last year and it looks really nice, but when you score 100 points it'll display as 1100. If you score 500 points it'll display as 5500. So, definitely something not right there and I have isolated it to the MPU board itself since a different MPU board works fine in the machine.
I have to fix some of the displays on these old Stern/Bally games too. Many of them flicker, or have a bright digit, missing digit or segment -- some of them behave for a while and then flake out. I've been wanting to make my own display out of LED segments so I could use it on the bench when testing, rather than having to wonder if a missing segment or digit is the display itself or a connection issue. Maybe it'll lead to a sort of "test fixture" so I can have an easier time fixing some of the board issues. We'll see..
Anyway, that's it for now, more projects very close on the horizon =]