The reason Mica caps are used in the oscillator circuit is because they are extremely stable. Even under heated conditions, they just do not drift, and they are usually more accurate on their value. This affords a very stable, and consistent frequency. Ceramic caps are generally not used in those types of circuits, because they tend to drift, and are very touchy when it come to heat. They are mostly just used in bypass circuits where accuracy is not critical.

@jacklick

3 ай бұрын

Thanks for the comment and info. I mistakenly said mylar vs mica in vid. Went down 🐇 hole ... always learning new stuff in this hobby.

Great job on the PCB build! and programming that NVRAM is weird. I had no idea you could do that.

@jacklick

3 ай бұрын

Thanks. Yea, I wouldn't have thought of programming the nvram without clue. I was puzzled why mame had a dump of the nvram...probably so it doesn't error out either.

Excellent work. That's one finished and done!

@jacklick

2 ай бұрын

Thank you! Technically, I still need to replace the ceramic caps with mica in clock ckt, but I like calling it done too! :)

@luckylukev

2 ай бұрын

@@jacklick None of my 15 cabs are "Done", there is always a little thing I could change or clean better, and that the fun part of it.

Such a fuuuuuuuun game :)

@jacklick

3 ай бұрын

Yea hopefully I won't procrastinate too long getting full cab together.

Why would a switching power supply causing timing issues of the read/write times for the NVRAM? you mentioned it in the video at time 9:40

@jacklick

3 ай бұрын

I linked to the thread that discusses it. It reportedly has to do with how long it takes for 10v unregulated to drop below 8v of zener to trigger write vs how long 5v stays available so nvram is still operational to support the write. In an originall cabinet, there is like a 10k cap on those lines vs on bench it is not. I didn't see the behavior on my bench but also didn't change settings or hs.

@waynegram8907

3 ай бұрын

@@jacklick yes all arcade games used the big blue 10,000uf to 20,000uf cap, is this what you're talking about that is keeping the 5vdc stay longer on the NVRAM? When you turn ON a switching power supply it should output +5vdc, -12vdc and +12vdc, why would they drop in voltage or have different timing of voltages?

Most arcade games use Chicklet Style Size Capacitors. Why do they use Chicklet capacitors because the Chicklet must have to do with either the temperature or ESR.

@jacklick

3 ай бұрын

It must

@waynegram8907

3 ай бұрын

@@jacklick I think the chicklet capacitor housing is made out of the same material used for power resistors for stability and heat

Down the rabbit hole with nv ram... This kind of research can be troublesome

@jacklick

3 ай бұрын

Let me know if find anything additional out.