In a recent live stream, the subject turned to flux on circuit boards and whether you should try and clean the flux off after you've soldered and I've never really done that and it inspired me to dig out some old circuit boards, including the sucker boards for this game which dates back to 1995.. hold on, let me just grab a circuit board here. Um, this is the Proto type 1995 so it's now 2023. That's quite some time, isn't it? That's about 28 Euros that this uh circuit board was made and looking at the back of it, there's no sign of any corrosion.

Normally with when copper crew, you'd expect CS of Green crustiness from the oxidation. Um, if the other will, if the lead had corroded, you'd expect to see a white residue, but there's nothing on either of these circuit boards so that kind of makes me think you know I Don't think it's really an issue with the hard flux. the wet Plumbing type flux, you wouldn't really want to do that, you'd want to clean it off. but in the case the hard rosin flux, it's not such an issue.

So this was a game. uh for a Fairground and it was basically A Wheel of Fortune type game and it was quite interesting because uh, it's based on a microcontroller. This is the emergency backup module. This isn't the main unit that was used in the commercial versions.

the menu used the commercial versions was much bigger and a big huge illuminated fruit machine style buttons, slot machine style buttons, and uh, it also had speech so that as well as playing sound effects are just randomly slipping things like it's the number one game sensation Casino Royale and just you know, random things. uh. In amongst the the advertising sequence, uh, done with information storage devices chips uh really strange chips they were. You controlled them from the microcontroller and triggered to trigger them and then they played back in what was basically analog memory so you could record into them and then they'd play that back with sort of pretty much CD Quality: Not bad.

Um to control the displays. The microcontroller on this one. it's a Pix16f No, it's a Pix16 C54 How old is that? Uh, but that controlled the displays by using zero data under its uh, synchronous Network it uses its clock and data and uh, it. this is a mimic display.

The main displays had tungsten lamps on them and to control that number of lamps uh, the before lamps in series: six volt lamps across 240 to control that number of lamps. it used Tracks under this small transformer wouldn't normally be enough to drive the track because they take quite a lot of current and I used various cheating techniques to actually allow um, it to run use a small transform to drive quite High current to these tracks. and the way I did it was with this circuitry. Here you can see the resistors here going to an AC up twice later and that uh, this is our standard sea Road parallel LED display driver and it's got a resistor that sets the current and the output which was set for the triac triggering and uh, there's a up to isolator I'm trying to remember how it did it the opto isolators in the series with that I think is it and it uh, basically gated the output current so that as the mains past the zero crossing point, it just pulsed the output current to the tracks.

So this small transformer can do that because uh, just basically 100 times a second would just provide that trigger pulse at the start of the sine wave. I can actually see looking at the prototype here. Here's the Prototype which has a resistors to emulate the tracks and it has the floating leads for the test resistors and also the remote in it with a capacitor to cause a slight phase shift. um I Probably scope this with an isolated scope to work out the point that was triggering in the sine wave and it just by adding the capacitor it would cause a slight phase shift which would result in the a longer pulse at the start of the sine wave instead of at the end of it.

Um, so that was more or less it in hindsight these days, knowing what I know now I'd Use our Rs-485 driver for this. It's an up to isolated input, dual up twiceolated isolator with a couple of LEDs to show it the actual data is present. but uh, the Rs-485 is better driving networks. This was a very simple circuitry using this, but it worked and that's the main thing.

Uh, anything else worth saying about these? Not really. No, it worked. It was a successful enough game. The only awkward bit was, uh, me recording all the voice samples.

It just felt a bit odd. this uh, censored slightly. uh, this is our tin plated circuit board where I've basically dipped in the tinning solution and after etching it and this, this again shows no signs of the corrosion. So I'll give you a demonstration of this, but a warning advance that it's about to get very, very loud because I've I've Jerry rigged up a audio interface because that's a microphone level output.

I've used a potentiometer and a spare radio microphone to couple that onto the receiver. which means that you'll be able to hear the game playing at full noise if you see it pauses there during the sequence. That's because it's playing a sound effect or triggering the sound sample the speech sample. Um, which isn't this I mean unit.

There are three buttons to operate. There's the reset button. there's the Uh, which just basically resets the whole game from scratch start which puts it into the Um, the initial pre-play mode and then that lights and the main unit that lights a big huge round eliminated button that could be passed out to one of the players so they could press it to start the game just to show that it was completely random. And it was completely random.

although there was a cheap mode if needed to make sure that uh, it biased in the operator's favor. in hindsight, if I was rewriting the software, if I was doing it again, I would uh integrate other features I would add: if maybe it was quiet there weren't enough players to actually play the full game, then I would incorporate a feature that one person would play and basically speaking, it would do that. sort of like the standard family entertainment center type game where it rotates and you have to try and stop. and the one that's uh, the sort of central one or something like that.

and again, if they're just to avoid um, paying out too many prizes, I'd do exactly what they do in the family entertainment centers. There's sort of arcades these days and I'd basically just bias either side. so when they paid out in percentage, but you know there's a one, everything's in software, so it's completely versatile. But anyway, I shall give you a demonstration of this now.

warning you in advance: it's about to get very loud because it's got lots of uh Square wave sound effects generated in assembly code in the processor, so it's going to sound a bit, um, arcadish right now. let's play a game. Headphone alert Things are about to get loud. When the operator wants to start the game, they press start it initially skitters about randomly and then I heard of the operator can start the spin or remember the public can hit a big red button to start the spin and then it does this.

During the main spin, it reduces the volume and then steps back up again. thank you and then it goes back into the advertising sequence and the game can start again. and there we have it. So that's kind of answered the question about the flux corroding.

It's certainly there may be some fluxes that do it. Let me know what you your experiences are in the description down below because I've just never really had an issue with flux corrosion of stuff except in the early days of the lead free era when they were using really aggressive fluxes to try and get this order to stick to stuff. I've noticed that on some situations the flux that they've used maybe they've maybe used a paste flux and I would recommend washing paste flux off afterwards, but um, in some of those instances I've seen significant corrosion. Um, what else can I really say here? um I would recommend in surface mount washing off the residual paste flux, but you also have to consider that if I was cleaning the flux off this, then it could potentially get into things like the sockets and stuff like that because if you're using isopropanol, it would dissolve the rosin and then it would start creeping into places.

And that could cause more problems, particularly things like potentiometers, but that is it. A little Showcase of uh Fairground games, as well as a discussion about the flux.