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Machined playfield today, now to make the ball release bar.

Wow! That's come up beautiful 😀 I used to love these old BWB games. There was another one like it called Windfall, with apple-cores on the reels instead of coins. And then you had Win Strike, Rat Race and so on. A great era of 2p fun 🙂

ok, so I only have mpu3 reel board circuit, but that also uses a 4049, so working from that the sensor supply is 5v through a 330k resistor, so the max current flow through the opto sensor works out (with ohms law, you can check it yourself) at 15uA max current flow, so if MPU2 uses the same these will work

Not written up an MPU4 for a while so .... This one came in doing all sorts of odd things before it died so I suggested sending the PSU as well just in case. The PSU was fine and all the caps had a good ESR so that rules that one out. Moving on to the board, most of the components around the battery area needed replacing and anything else with green legs. On switch on it did boot but with garbage on the alpha and then nothing. Luckily there was no track damage which was confirmed by tap'ing out the tracks to the alpha. In fact the only track damage was the negative battery pin which had become isolated. A rivet and some copper sorted that. So where do we go next? The first diag test is the triacs and all was good in that dept being as I'd alread swapped out all driver transistors, the 1nF caps and the zener diodes. This comes from IC8 which also has a drive to the alpha. The other drives to the alpha come from IC3 (68B21) so out she comes, in with a socket and a new one and bingo it now says MPU4 ALPHATEST OK. Are we done? Don't be silly, up comes the 7 seg display then it alarms with something like @@@@@ALARM 7xxxx (some other odd characters). Usually once the alpha is working it will tell you what the next error is but in this case it was garbage. The next thing the diags test is the RS232 and the meters (could be the other way round I can't remember) so I blindly changed the two IC's responsible as neither of them were producing the required outputs (IC7 + IC5 68B21). Next boot up and it's still the same.OK, I have seen a 6840 ALARM around this stage so a quick swap out and ....nope! Next thing switch on again and nothing??? The RESET circuit has failed. Should have swapped out these transistors originally, ho hum. So I'm running out of IC's to change so where next? After being on a few minutes with the alarm sound driving me mental I noticed IC6 was cold whereas all the other PIO's were warm. Hmmm, in with a new one and everything sprang to life. That was a relief.

Was a decent game, obviously would have preferred the adders and ladders it once was, but better than it being sat as fire wood. off to its new happy owner already. Another one rescued and saved 😇

The CD4049 ic Supply Voltage (V+ to V-). . . . . . . . . . . . . . . . . . . . . . . -0.5V to 20V DC Input Current, Any One Input. . . . . . . . . . . . . . . . . . . . . . ±10mA

They switch a 4049 chip and without looking up the datasheet I've got no idea what the input switching current is although it is likely to be very low of course. The main issue I've found during experimentation is modern devices seem to be much more sensitive and any stray light sets them off. The caveat with that is I didn't know what the angle was of some of those devices. The old adage I always use is 'suck it and see' bit like oral sex really!

this is the current it conducts with light to bring the voltage down for the input of the next stage which i presume is a chip, bob will know more as i have never dealt with circuits earlier than mpu3

Back up and running