Entries in this series:
- 1) TS1000 upgrade « you are here
- 2) More Power!
- 3) On The Big Screen!
- 4) Oh the memories we’ll make with 16k!
2022, 12 , 14
#retrocomputing has been taking up more of my attention recently. Specifically, I found this series about refurbishing and upgrading a Sinclair ZX81. Since the Timex Sinclair 1000 is essentially a ZX81 that jumped the pond (and doubled it’s native RAM in the process), I’ve got one. And it’s been sitting in a box for 20ish years, used heavily previous to that.
Time to rectify (ha!) that situation.
After removing it from the case, and admiring how clean it is after all this time — the capacitors look great!! — I’ve determined that there are four things that need work, maybe five. Ok, maybe six. Also some sources for inspiration / reference:
- Convert video output to Composite – so I can see what the heck is going on. Found this source somewhat locally – well, it’s within Canada and only a few provinces over, so that’s local.
- Upgrade the power converter – so it runs cooler and doesn’t need that big honkin’ sheet of aluminum to dissipate waste heat.
- Expand the onboard memory – a very simple upgrade that will eliminate the true ‘vintage’ experience of having your ongoing work lost due to a minor wobble while entering code.
- Upgrade the CPU to a lower power version – lower power use keeps things running cooler, and modern production methods may mean it’ll last another 40 years? Since the current CPU is socketed, this is a simple chip swap. Or maybe not! I’m liking the bling thing so will replace the current socket with a gold one 😀
- Potentially (heh, I slay me) replace the ULA chip if it’s bad. They’re notorious for running hot so this is likely in the cards anyway.
- Replace the two capacitors with new ones.
But before getting started, I’ll need to figure out if this thing is even working. And since I don’t have a vintage TV or monitor able to display the RF signal, I’ll have to break out my tiny new oscilloscope and probe around.
After a conversation with the provider of the Composite mod PCB, and reviewing one of the videos that started this whole thing, I’ve opened up the little dude and started probing.
And things look good! This is the output video signal before it gets to the RF converter, so yeah, it’s alive and trying to show me stuff. Which means that the ULA is ok and upgrading it is not a high priority.
Further poking around the ULA and the CPU also gave off signs of life. Looks like we’re good.
And that’s pretty much where I’ll end this first log entry. Depending on how things go with mail delivery, etc, the next step will be either upgrading the power converter, or installing the Composite PCB.
- Always ensure power is getting to the part you’re probing. There was a bad lamp-switch installed inline on the power supply cord which gave intermittent power to the system. Frustrating to have your power be there one moment, gone the next. Fix was to replace the switch. Eventually I’ll 3D print a proper box for it.
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