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Sharp X1 Twin Pico PSU PCB replacement

ImportantBet

ImportantBet

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Ok, so my PSU board is pretty much dead. I already did a full recap and replaced some power transistors. I still got a bridge rectifier and a bad diode to replace before I fully give up on the original board. I was able to get my computer working with a temporary ATX power supply though.

Meanwhile, I'll be modifying @mattsoft's existing design from his X68k Pico PSU project to fit my needs for a new X1 Twin power supply PCB replacement. Since I need to make a minimum order of 5, is anyone else interested in purchasing/splitting manufacturing costs? I know @NFGx has one.

The PSU enclosure is a lower profile compared to the X68k's, so I recommend to get the shorter AC/DC converters listed on mattsoft's github:
  • MEAN WELL RPS-120S-12
  • MEAN WELL EPP-120S-12 (22 week lead time as of this post)

Alot of people don't have these machines so if you know someone who does, let them know about this thread! Thanks!
 

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I suppose I'd better replace mine before I fire it up and discover it's on fire, or worse. Do you have a cost estimate?
 
I will probably have to get back to you on that when I do quote comparisons between OSHpark and JLCPCB
 
I bought my X1 Twin completely dead a couple of years ago and faced with having to replace the PSU. I bought a standalone power supply that provided +12v and +5v as well as the other things required of the system (+5VSB and switch signal) to get it up and running. I ended up with the following pinout...

X1 Side - PSU Side (fed from ATX power supply)
Red = +5V (Red wire on the ATX Connector)
Black = Ground (Black)
White = +5VSB (Purple)
Purple = power on (Green)

I forgot which PSU I got but it fit into the space the old one left behind making it a very clean installation. In any case, it would be wonderful if someone here can verify the voltages on a working machine. I've had a gnawing feeling that I've got something wrong and confirmation of the above would put me at ease. Having said that, the system does work 100% but for a very strange graphical glitch that occurs ONLY when LOADING games on "SYNC A" set. I don't want to get into it too much here but if I load a game into memory in "SYNC A" mode, it will play back with corrupted graphics. If I load the game instead with "SYNC B" set, the graphics are perfect and remain so if I switch between modes....VERY weird.
 
It could be a issue with a component on the motherboard. As long as the rails output their respective values, I don't see why it shouldn't be a problem.

Anyways, the design is still in progress and should be finished in the following weeks. Been sidetracked with other projects lately.
 
As of November is there any progress on this project? I also own an X1 Twin, but mine works fine after restoring it.

I've done a few high-voltage designs with some being public. Did you need any help?
 
Slowly, but surely. Currently multi-tasking on a few other projects. I've recreated the pcb cutout 1:1 to fit in the original aluminum enclosure.
 

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What is the power rating of the computer? Should say something like 39W or something like that on the dataplate?
 
@Cyothevile Yeah the wattage is something like that. That Mean Well is a 5V single ch output. I actually plan to get my FDD up and running since I have some physical copies of X1 5.25" disks.

If you want to contribute, may I ask what connector they used in place of the usual expansion pins on the PCE board? I think @NFGx mentioned this before in his disassembly thread where it seemed to be similar to VHDCI.
 
As the X68000 these PSU are almost all fixable, the only times I wasn't able to do so were when the transformer was dead.
But it need some time, you have to replace most of the components (small resistors, transistor, diodes, optocoupler) and obviously chemical capacitors.
At least, you'll keep this computer in it's original state. I'm not favorable to replace the PSU on these old computers, let us keep them as original as possible.
 
aje_fr said:
As the X68000 these PSU are almost all fixable, the only times I wasn't able to do so were when the transformer was dead.
But it need some time, you have to replace most of the components (small resistors, transistor, diodes, optocoupler) and obviously chemical capacitors.
At least, you'll keep this computer in it's original state. I'm not favorable to replace the PSU on these old computers, let us keep them as original as possible.
Click to expand...
Not everybody has analog circuit knowledge to diagnose and repair these power supplies. What about instances where diodes fail and there are no markings on them? Most people don't know what to do outside of changing capacitors.

I bet 90% of this forum that "repairs" arcades or computer items will not know what to do outside of changing capacitors. Guarantee it. Hence the desire for projects like this. This is not meant to be a disparaging remark; it is just the reality of why "replace power supply" projects begin.
 
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