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 Post subject: MK119 Roulette kit
PostPosted: Thu May 18, 2017 2:14 pm 
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MK119 Roulette.
I have a problem with one of these kits. Numbers 5, 24, 16, and 33 do not light up. 5 of these kits were built by Yr8 students and all others work ok apart from this one. I have checked polarity of LEDs, swapped the I/C with one of the working ones- still no luck, checked tracks and for shorts. I have also noticed that as the sequence goes round on pressing the button it runs 1, 20, 14 then 1 and 20 light again! Any ideas please before I loose what little hair I have left!!


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 Post subject: Re: MK119 Roulette kit
PostPosted: Thu May 18, 2017 2:46 pm 
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You should post clear pictures of the front and back of the kit.
Also did you check holder for IC1 pin 8 to make sure is not bent and not going through the hole?
Have you checked for continuity from IC1 pin 8 to R11 and from R11 to LD5 ,24, 16 and 33?
If you look at the schematic you can tell which side of the LED to check it at.


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 Post subject: Re: MK119 Roulette kit
PostPosted: Fri May 19, 2017 1:06 pm 
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Many thanks for that info. I will have to bring my meter in next week and do some checks as you suggest. I have also found that if it stops on 20 or 31 both light up and the same with when it stops on 19 or 32 the same thing happens. Whether this put any more light on the problem or it is all connected I don't know. I will certainly check what you suggest next week. Thanks again, Brian.


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 Post subject: Re: MK119 Roulette kit
PostPosted: Fri May 19, 2017 2:52 pm 
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This sounds like a short nut I can not say without looking at the board.


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 Post subject: Re: MK119 Roulette kit
PostPosted: Mon May 22, 2017 8:36 am 
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I have checked continuity as you suggested but surely R11 is on pin 7 of IC1, It's R10 to pin 8. will try to get some good photos and post when I can.


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