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Re: ‘Tatung 81’ (ZX81 in a case)
Posted: Fri May 28, 2021 4:15 pm
by BarryN
Lardo Boffin wrote: ↑Fri May 28, 2021 1:58 pm
Plugged in and switched on - no explosions! Also very little voltage at the 9V plug by the zeddy. About 0.08 so not much going to happen there!
Hey ho.
So then, with only 0.08V out from the 9V power supply, I'm guessing it doesn't work yet.
Re: ‘Tatung 81’ (ZX81 in a case)
Posted: Fri May 28, 2021 4:28 pm
by Lardo Boffin
BarryN wrote: ↑Fri May 28, 2021 4:15 pm
Lardo Boffin wrote: ↑Fri May 28, 2021 1:58 pm
Plugged in and switched on - no explosions! Also very little voltage at the 9V plug by the zeddy. About 0.08 so not much going to happen there!
Hey ho.
So then, with only 0.08V out from the 9V power supply, I'm guessing it doesn't work yet.
Sadly not. I will remove the zeddy from the case and try that. Hopefully that will be ok then it is just a matter of deciding what to do about the PSU.
Re: ‘Tatung 81’ (ZX81 in a case)
Posted: Fri May 28, 2021 4:33 pm
by Lardo Boffin
In amongst the box of stuff I also found this lot:
Re: ‘Tatung 81’ (ZX81 in a case)
Posted: Fri May 28, 2021 4:33 pm
by Lardo Boffin
Re: ‘Tatung 81’ (ZX81 in a case)
Posted: Fri May 28, 2021 6:27 pm
by 1024MAK
Lardo Boffin wrote: ↑Fri May 28, 2021 1:58 pm
Plugged in and switched on - no explosions! Also very little voltage at the 9V plug by the zeddy. About 0.08 so not much going to happen there!
Hey ho.
Aren’t you supposed to connect up to a nuclear power station first?
So have you checked those fuses? Obviously with the power off, use the continuity range or the resistance range.
Next up, just unplug the 9V power jack plug and use a normal Sinclair PSU...
OR, power up the existing power supply and test the voltage across the leads of both of the large electrolytic capacitors. But do be careful to keep clear of the mains wiring, fuses and connections.
Mark
Re: ‘Tatung 81’ (ZX81 in a case)
Posted: Fri May 28, 2021 8:24 pm
by Lardo Boffin
1024MAK wrote: ↑Fri May 28, 2021 6:27 pm
Lardo Boffin wrote: ↑Fri May 28, 2021 1:58 pm
Plugged in and switched on - no explosions! Also very little voltage at the 9V plug by the zeddy. About 0.08 so not much going to happen there!
Hey ho.
Aren’t you supposed to connect up to a nuclear power station first?
So have you checked those fuses? Obviously with the power off, use the continuity range or the resistance range.
Next up, just unplug the 9V power jack plug and use a normal Sinclair PSU...
OR, power up the existing power supply and test the voltage across the leads of both of the large electrolytic capacitors. But do be careful to keep clear of the mains wiring, fuses and connections.
Mark
I’m legal not allowed to go near power stations…
I checked the fuses with the continuity setting and both are fine. I will check the zeddy at some point.
When I’m feeling brave I will check the caps voltage. I managed to a fit a BuzzOff to my Vectrex without killing myself so hopefully will be ok!
Re: ‘Tatung 81’ (ZX81 in a case)
Posted: Fri May 28, 2021 11:35 pm
by Lardo Boffin
The zeddy and keyboard work fine! Picture is pretty good as well.
Re: ‘Tatung 81’ (ZX81 in a case)
Posted: Fri May 28, 2021 11:37 pm
by Lardo Boffin
Maybe this is the home my rebuilt zeddy has been looking for?….
Re: ‘Tatung 81’ (ZX81 in a case)
Posted: Sat May 29, 2021 11:25 pm
by Lardo Boffin
Found a spare ZX81 (minus case) in the box with the Tatung 81 - in a bag cunningly labelled ‘Replacement mainboard’ (check out the bent heatsink!). No K initially but after some chip swapping it is up and running. The Z80 had died - I’m pretty sure I have had more dead Z80’s than ULAs now.
The heatsink on the ULA is of course nothing to do with me! I guess in the context of the size of the case it made some sense.
Re: ‘Tatung 81’ (ZX81 in a case)
Posted: Sat May 29, 2021 11:26 pm
by Lardo Boffin