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Fujitsu MB14241 IC Replacement


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I have a couple of Taito 3-Layer PCB's that need a Fujitsu MB14241 IC.

Supply of these have been running out and I can only find one supplier in Japan that still has some.

I did a bit of research and found a schematic that was drawn up to mimic the operation of the the chip which can be used as a replacement.







I've redrawn it using EasyEDA..







I'm at the point where I'm ready to do the PCB layout.




This is the first time I've used this software and was hoping someone could take a look at the project and make sure all is good before I spent the time doing the layout only to find it needs to be redone.

Any tips are most welcome as well.


I'd like the smallest footprint as possible, the 24 pin dip socket will be substituted for header pins to connect to the SI Sound PCB.




I'm happy to share the project files with anyone who has experience with EasyEDA that want to take a closer look for me.




Edit: I hit Autoroute to see how it would go and only have a few tracks left to route.




An hour later and job's done... Is there anything I'm missing?

5v and Gnd track width okay?







On a side note I found this when doing a bit more research and the MB14241...



Edited by Kaizen
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Seams to be a lot of work for just one chip

Hmmmm.... stock of obsolete chips :o

Q:- did you put out a "Wanted to Buy" thread ?

i have been buying up old stock for many years


Like with a lot of rare/obsolete chips, people buy up and hoard the remaining chips then the prices go through the roof if they are even willing to part with them.

What I'm trying to do here is provide a long term solution for the community which is open source that will keep these boards that require this chip up and running.

The boards will cost about $5 (when purchased in a lot of 10 plus postage) and the chips work out to be $10-20 depending on where you source them from and how many.

From my point of view it's not a lot of effort, I need to learn how to design PCB's and the project will provide plenty of experience.

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may have some PCB's for you to design..

i have had a go at it but can only do them in Auto CAD & not been able to convert to any type/program that could be used..

MB14241 .. if i remember these only cost me $11.50 each

i have been hording "yes" but to help maintain my games & to have a few chips to help others when i got extras..

Edited by Pac-Invader
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Board layout is now done with some help from @Frank_fjs.

I learnt plenty from the process and will order the boards next week.

There's no difference in price whether I order 5 or 10 so I'll order 10 and hope that it works correctly and I haven't made any mistakes drawing up the schematic.

All parts are available from Jaycar.



Edited by Kaizen
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No need for a cap across the power pins on each IC?.


Gotta love these hacks to overcome custom chips. These hacks were common on pirate boards and where called daughter boards where the hacker assembled many chips on it to substitute the one custom chip they were unable to get. The daughter board did the same function as the custom but was made of ICs that were common and as a result, well tested. This goes a long way to explaining why a lot of pirate boards are the only ones running today while the originals using custom chips are long dead.


Because we were always putting in the very latest games, it become apparent many of these latest games with a host of custom one off chips were prone to failing before the warranty of the board had expired. Boards were replaced free of charge and the thought was always this board will fail again just like the last. Most of the time the board then lasted until the game was no longer making money and it was removed and replaced with another latest game.

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I was wondering about power requirements myself.


I think we should at least increase the width of the power traces. We can go up to 12mil without any drastic work. 15mil is possible with a bit of effort shifting the traces around.


The LS chips seem to draw low power, 16mA each maybe, but there are 12 of them.


I'm guessing the main source of power will be the MB14241 socket of the game board, which I assume at least has a 0.1uF across the power rails.


I'm wondering if we can add a single larger value capacitor to cover the 12 IC's?


Paging @David_AVD

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Wow like your work :)

Jaycar 74LS151 = $1.95 each :o

if you buy in bulk can get these down to $0.36 cents each


P.S.. i found an old Midway Service Bulletin dated 14 April 1980 ( in my stash of manuals )

stating a supply shortage of MB14241 chips , they supplied an auxiliary PCB using 4 x 25S10 & 4 x 74175

so i do not think you new PCB will be a problem with power draw..

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Cool.. great to see progress..

but even at $0.36 cent each for 12 chips + PCB & headers it still more than original MB14241 chip

Sorry i'm only new here & was not here back when others had asked for them in the wanted section

i have no shortage of this chip :)

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  • 2 months later...

Did They Work?


I have been interested in a MB14241 replacement for a long time now. I saw the first schematic a while ago and have been trying to get Spaeth's CPLD replacement for a while too.


I am very interested in knowing how these turned out and if the plan is to sell the boards (bare or populated?) or have people get their own boards fabbed, or...?






-=- James

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  • 2 months later...
The PCBs arrived today, three days from putting the order through to delivery.




I ordered 10 boards and received 11, I also ordered five Taito TC0070RGB custom boards.





Nice Work Kaizen,


I am gratefull for the work you do and information you share about arcade repair, time and time again as I learn it seems to be your posts I end up at!


I currently have a 3 layer with one of these MB14241 chips. It was socketed and on removal two of the legs came straight off, the others are pretty corroded.


I am going to attempt a repair of the chip I have removed but if this is not possible, are you able to supply me with a board to the UK?



Failing that would you mind sharing the project file and I could order and populate myself?


Thanks Duncan

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  • 2 months later...
I purchased a few MB14241some time ago and sold a few to members here, Found the same problem only could get them from one place in Japan. Could do so again if the need was there but your plan looks better with providing a long term replacement option, as the MB chip will run out of stock one day if not already.
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  • 2 months later...

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