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Showing results for tags 'royal diamonds'.
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Hi all, I've been lurking here for a couple of days and read up on much of what is available here on the Barcrest MPU3. Thank you so much Midibob for all the info you so freely shared! I have owned a Barcrest Royal Diamonds for years, acquired it in '97. It was missing a 7 segment display (easily built) and the battery was bad (easily replaced). No real damage to the board nor the transistors. One 74LSxxx was bad. When I couldn't figure it out I (get this) called Barcrest, got connected to their Technical Department and ended up talking to a guy who helped design this particular game! His tips quickly led to a faulty 74LS12 (if I remember correctly) and it has been playing ever since. Well, that is; it was stored in the back of the garage for the last couple of years and then, on trying it a couple of months ago, it wouldn't budge of course. I have some experience in repairing electronics, am a HAM, and have restored a couple of Solid State pinball CPU boards (most of 'm damaged by battery leakage). So, after reading up here on the MPU3 stories I tackled the RD last weekend. It was ever so simple... the battery was flat but when connected to a separate Power Supply it charged neatly and holds its voltage for at least a couple of days. Checking the Test Points with a multimeter and a service scope gave a funny reading on the RESET line: it stayed low. Well, the board should not be resetting continuously and a quick look at the schematic suggested bad transistors or a bad Tantalium cap. I do not have any of the transistors in my junk box, but a reasonably fresh 10uF Tantalium cap was. Replaced it and Presto! If life would only be so simple more often 😉 Tested the game this morning and after resetting all the readings seem to indicate everything is working. The only things left now: I have a wiring diagram for the Royal Casino which is probably very like the Royal Diamonds but I'd love one for the RD. Also, the green diamond lamps all light up just as bright as all the others but still they are poorly visible. I wonder if the glas is dirty on the inside? Hope this will do as an introduction. Now everything is running I'll probably won't be visiting daily, but I thought it only polite to let you know how the forum, the info and you people are appreciated! BartW. PS: Oh yeah, one thing that has been bugging me: what the heck is the 'Aerial' used for that is tied into the Harness??
