Uploaded July 2026 | Updated September 2026, 2 weeks ago

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Jupiter Ace repair!? Well yes!

Also a huge thanks to my sponsor PCBWay and happy 12th Anniversary! pcbway.com/activity/anniversary12th.html

A non-working Jupiter Ace replica, designed by Cees Meijer, recently made its way to my bench after being handed to me by Pajaco Paul at RetroFest. The system was outputting a garbled screen and failing to boot. By stepping through the standard 8-bit diagnostic process, I checked the power rails, tested the 74LS logic chips, and eventually tracked the primary fault to a missing clock signal at the Z80 CPU.

The issue was isolated to a single faulty transistor in the clock generation circuit. After scoping the board, finding a suitable replacement, and restoring the proper clock pulse, the system booted successfully to the Forth prompt. I plan to tackle a custom 3D-printed enclosure for this board at a later date.

Thank you to Paul for passing this project along, and a huge thanks to those who support my bench work through Patreon and channel memberships.

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If you'd like to help keep the lights on (and the tools plugged in),
my Patreon is the best way to do it. Patrons get ad-free early access
to videos, behind-the-scenes updates, and entry to a super secret
Discord channel — plus my sincere gratitude, which is worth roughly
what you'd expect.

▸ Patreon: patreon.morefunretro.co.uk

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There's also the Retro Hardware Discord, where people who enjoy this
sort of thing gather to talk about it. It's better than it has any
right to be.

▸ Retro Hardware Discord: discord.gg/tsAbuAfqf9

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Second Channel: @morefunretro2 ​

#JupiterAce #RetroComputing #ElectronicsRepair