Man - way to shit on the guy's thread.

I think the board looks nice. Good upgrades.

Yeah, it probably would have been a better idea for the bottom section of the board to be through-hole components for reparability. Or, at least provide the through holes so a new chip could be installed--like on @barakandl's classic bally/stern driver board.

Sounds like a good idea. I don't think anyone else has done that yet on an aftermarket WPC MPU.

Huh, never realized how simple the schematic really was on the WPC-89 boards. Once you empty the real estate by moving to SMT, it starts to look downright elegant in comparison to the originals. Nice clean layout, well done! Does it still include a real-time-clock? Not sure what WPC-89 games had clock based features.

To answer the other questions that came up.....

As a hobby, we have to get used to surface mount components, thru-hole stuff is being discontinued left and right by every major supplier. We're hitting the point that duplicating old designs with thru-hole parts is simply not viable any longer. As a hobby we must adapt as there's no other option. I can't remember the last time at work that we brought in a new design for a customer that had a thru-hole IC other than opto isolators. NOBODY is designing new thru-hole product in any quantity. Too big, cost too much, costlier to manufacture, and harder to design boards with thru-hole IC's. Once you get used to it, even repair work is often easier and quicker with SMT parts than thru-hole. Just takes some practice.

Seriously, the semiconductor market right now is absolutely bonkers. We're getting notifications on a daily basis of huge lead times, parts being discontinued, last time buy notices, you name it. Atmega processors are a two year lead time right now and still extending. PIC's aren't far behind. Hell, I just got a 4 month lead time for molex crimps.

The power supply idea is well proven via existing daughter-board kits. This design integrates it into the CPU board as opposed to having it as a separate module. There's no concern at all. Good solution to drastically reducing reset issues.

Sound boards for many designs are impossible to make exact duplicates to the originals. The original DAC chips are long obsolete and not available in any reliable quantity, and audio amp chips are also disappearing in rapid succession. One customer at work is on their third major redesign because of audio amps being discontinued.

The boxed in ribbon cable is a great idea. I can't count the times I have seen ribbon cables put on wrong.

Or worse, they take your design and run with it.

I think this is a step in the right direction. SMD components are a challenge to repair, but when older part styles become obsolete, we have to adapt. You have implemented a good solution with the DC/DC converter. I did not like working on SMD boards at first, still don't but just have to. My 2 cents is all I am saying.

Ken

Mybe I'm missing the battery header, but how do you connect a battery to your CPU board for the ASICs real time clock (RTC) functionality in games with a Midnight Madness feature or a game like Twilight Zone that has a functioning Analog clock on the playfield?

I'm confused by why anyone would have to scour for "NOS parts" nearly every component in the original board is still available new for purchase.
No one needs to spend any time looking for any of them as they are all listed at the link below, this is a publicly shared document I created several years ago:
https://docs.google.com/spreadsheets/d/1C4znEqZd4K4eywhi__qDwI-3AsX6Y5qdw9Pzb0p178A/edit#gid=1430569459

I would definitely emphasize that in whatever advertising you end up doing - since your stated market is people that don't do board level work, they are probably also the same type of customer that would be upset not knowing this and wondering why their Twilight Zone clock doesn't work..... does the lack of the RTC working though cause the credit dot at startup for date/time not set? Could you easily add a header for batteries for this?

The RTC doesn't even keep good time anyway in the ASIC unless the game is on, even with good batteries. All my games are way off.

NOS parts (New Old Stock) means they are actually new parts made back in the day and are no longer available; but even this aside, you are actually misleading folks into thinking the original parts used in the manufacture of this board are no longer being produced and this is simply untrue.

Pin-Guy -- interesting list in that link.

As to definition of NOS. New Old Stock (to me) means new (unused) old stock but this has been debated many times. To me - parts that are pulled from equipment are not "NOS" but actually "USED". My favorite vendor description is "Refurbished" where all some of them do to refurbish them is pull them from the old board.

Parts that I consider obsolete and hard to find for that board (e.g. 'scour for NOS parts'):
Williams ASIC -- Might be still available from the last build that the guy in OZ made... I'm not sure.
EPROM -- Those are obsolete. Can replace with an OTP-PROM (which is still made, footprint compatible and cheaper anyways).
CPU -- That one truly is no longer made with no replacement, can become a bugger as they get scarcer.

To the OP - I think the choice to use a 'point of use' regulator on that board is an excellent idea. Computers have been using that method for decades.
But I think the use of SMT for the parts that often get cooked (e.g. comparators and transistor array) is not such a good idea. If you really want to use SMT parts there, I suggest you put land patterns on the board so that when (not if) they do get cooked then they can easily be replaced with thru-hole parts that are still commonly made.

And - color code the LEDs! Human Engineering specs say 'Green good, yellow warning, red bad'. No biggie - just a pet peeve of mine.

Sheesh, you certainly didn't take my constructive criticism well at all..... newbie buyer replaces board, no clock, you get support emails. Could have nipped it in the bud by pointing it out beforehand.

Nobody here is bashing your work. Rather, simply offering suggestions on making improvements for a better product.

Unfortunate, but when you use terms like this:

Then you have no option to make the RTC work, you kind of set yourself up for this.

Yes, I provided an entire thru-hole parts list with quick links for every part on the original WPC89 board from one of the largest electronic parts distributors in the country.

Granted the CPU, ASIC, and Game ROM were not included in this list, since your board uses chip sockets in this location I didnt feel they were worth mentioning since they are all low failure items and are far away from the corrosion areas.

I agree, original ceramic UV erasable EPROMS are hard to find, but folks that actually burn and erase EPROMS are equally as hard to find, most people are just going to but the final version of whatever EPROM they need and not worry about it being plastic or ceramic.

Like G-P-E mentioned, these parts are no where near as expensive as they once were are there are tons of new One Time Programmable "EPROMS" available that will work just fine for folks that would rather burn their own.(Yes I do know the "E" in EPROM stands for erasable)

https://www.mouser.com/ProductDetail/Microchip-Technology-Atmel/AT27C040-70PU?qs=lURXKZrvvXdfU1rfB2oRWw%3D%3D
https://www.mouser.com/datasheet/2/268/doc0189-1368911.pdf

I already had the list as this was the parts list from the first 3 MPUs I built from bare boards; I just transferred the information to a spreadsheet and made it available to everyone. This is also why I can confirm I had a 0.00% parts failure rate, there is the one Capacitor on that list that became obsoleted and while I still many of them I never tested the substitute part on the full parts list.
G-P-E If you want to copy that sheet and put your own part number and links in it and publish it, please feel free to do so.

https://en.wikipedia.org/wiki/New_old_stock

It can be debated, but the one constant is that the part was never used.

This is very well said. I believe if you used a socketed U20 and added a coin cell battery or a battery header for the RTC; I think most people would be very happy with that.

Not needed by me, I have every confidence that it will work fine.

I don't need one either but thanks for the offer.

I would gladly take one of the first run boards if you are offering to others... I have a T2 which doesn't have any useful RTC clock features so no issues for my usage.

If you want some test data in a 24/7 commercial route setting in exchange for a discount I can provide that. We have an Addams Family that gets a lot of play.

Thanks for your generous offer its much appreciated but I am solid on spare boards and parts. I'm certain you will be able to sell them as new working beta boards; I see folks on here all the time that need replacements because of acid damage or botched repairs.