ZX81/TS1000/TS1500 Cleanup: Part 2

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The Clueless Engineer

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Published on July 18, 2023 11:23:34 AM ● Video Link: https://www.youtube.com/watch?v=cKFFo4kAyE4

Duration: 34:25

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21

Started work on updating one of the Timex Sinclair TS1000s, an Issue 3 board with a 2C184E ULA (missing "back porch"). In this video I [1] implement a simple composite mod (emitter follower), [2] replace the 7805 linear regulator and [3] replace the original ULA with a vLA81.

A good description of the missing back porch issue in the 2C158E & 2C184E versions:
https://retro.engineer/projects/2021-03-20_Sinclair_ZX81_video_board/

The stock power consumption was 360mA.
Replacing the 7805 dropped this to 230mA.
Replacing the original ULA dropped this to 160mA.

The resulting video image was a rock solid B&W picture.

In Part 3 I'll continue working on this machine:
[1] Upgrade the RAM from stock 2KB to 32KB,
[2] Replace some other components (to tidy up the board),
[3] Maybe replace the IC sockets, particularly for the vLA81,
[4] Replace the original keyboard membrane

Simple composite mod.:
https://www.bytedelight.com/?page_id=3560

vLA81 ... excellent replacement ULA:
https://www.vretrodesign.com

Other ZX81/TS1000/TS1500 videos:
https://www.youtube.com/playlist?list=PL5pwokf56wMLVboogvR4xuENeiSlZQJcW