White screen and no cursor at all
Re: White screen and no cursor at all
Here’s one on eBay: https://www.ebay.com/itm/Sinclair-ZX81- ... 672?_ul=DK
Re: White screen and no cursor at all
Thanks Martin, I have not seen this, but it is the american model I guess, probably from an Timex-Sinclar. I'm not sure if this ULA will be compatible with my Zeddy....mrtinb wrote: ↑Sun Jun 02, 2019 3:13 pm Here’s one on eBay: https://www.ebay.com/itm/Sinclair-ZX81- ... 672?_ul=DK
Re: White screen and no cursor at all
The only difference in a UK ZX81 and an US TS1000 is the modulator.
The ULA does not care. All is handled in software. The ULAs are equal. One connection on the PCB is open or shorted depending on whether it is sold in UK or US.
The ULA does not care. All is handled in software. The ULAs are equal. One connection on the PCB is open or shorted depending on whether it is sold in UK or US.
Re: White screen and no cursor at all
Thank you for the clarification, anyway I'll try to find an ULA here in Europe to reduce costs because shipping from the USA is almost double the price of the chip. Recently I bought a working ZX81 from Lardo Boffin and was only 37 pounds. Also maybe @Andy decides to issue a new batch of his ULAs, we will see.
As I'll take the ULA from the ZX81 that Lardo sent, my ZX81 will be ready to work and Lardo's one will be in standby until I cand found a solution but it will not be an urgent matter.
Re: White screen and no cursor at all
Well, finally I have located and ordered an ULA and while it arrives I made a "lifting" to ZX81 bought to @Lardo Boffin.
I found a small breakage on the flat cable that goes to the keyboard that has affected 8 keys but fortunatelly a cut with the scissors has been enough to go back to the normallity and now all the keys are working.
Later I recaped the board (very easy, only two capacitors), replaced the 7805 regulator by a more efficiente TracoPower and installed the Pokemon's video output PCB. Now it looks like this:
It took me a bit to adjust the video, I guess that the problem was the video - VGA converter so I connected the ZX81 to a DVD-VHS combo and although it rescaled the output signal to 1080p it has been much easier to adjust. When connected again to the PC monitor the signal was really good and stable to be a ZX81, I was surprised:
Although it only has 1K of RAM I have connected the 16K Memotech module that came with the first ZX81 and it worked like a charm. As the first ZX81 already have had the Wilco mod it has 32K inside then, the Memotech module will be used with this ZX81.
That's all concerning this ZX81, now once the ULA arrives I'll try to fix his brother.
.
I found a small breakage on the flat cable that goes to the keyboard that has affected 8 keys but fortunatelly a cut with the scissors has been enough to go back to the normallity and now all the keys are working.
Later I recaped the board (very easy, only two capacitors), replaced the 7805 regulator by a more efficiente TracoPower and installed the Pokemon's video output PCB. Now it looks like this:
It took me a bit to adjust the video, I guess that the problem was the video - VGA converter so I connected the ZX81 to a DVD-VHS combo and although it rescaled the output signal to 1080p it has been much easier to adjust. When connected again to the PC monitor the signal was really good and stable to be a ZX81, I was surprised:
Although it only has 1K of RAM I have connected the 16K Memotech module that came with the first ZX81 and it worked like a charm. As the first ZX81 already have had the Wilco mod it has 32K inside then, the Memotech module will be used with this ZX81.
That's all concerning this ZX81, now once the ULA arrives I'll try to fix his brother.
.
- RetroTechie
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Re: White screen and no cursor at all
Isn't that mini-pcb supposed to go into the modulator can? (after you rip its contents out). That would very much tidy up the wiring since all signals / power supply you need is right there.
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Re: White screen and no cursor at all
Once you adjust the ZX8-CCB you should get a really good picture.
For later ULAs I start with this position and then fine tune:-
Yellow lines added for clarity.
Before adjusting I always take a photo of the current position. Very useful when it gets worse.
For later ULAs I start with this position and then fine tune:-
Yellow lines added for clarity.
Before adjusting I always take a photo of the current position. Very useful when it gets worse.
ZX80
ZX81 iss 1 (bugged ROM, kludge fix, normal, rebuilt)
TS 1000 iss 3, ZXPand AY and +, ZX8-CCB, ZX-KDLX & ChromaSCART
Tatung 81 + Wespi
TS 1500 & 2000
Spectrum 16k (iss 1 s/n 862)
Spectrum 48ks plus a DIVMMC future and SPECTRA
ZX81 iss 1 (bugged ROM, kludge fix, normal, rebuilt)
TS 1000 iss 3, ZXPand AY and +, ZX8-CCB, ZX-KDLX & ChromaSCART
Tatung 81 + Wespi
TS 1500 & 2000
Spectrum 16k (iss 1 s/n 862)
Spectrum 48ks plus a DIVMMC future and SPECTRA
-
- Posts: 2169
- Joined: Sat Nov 26, 2016 2:42 am
Re: White screen and no cursor at all
RetroTechie wrote: ↑Sat Jun 08, 2019 8:38 pm Isn't that mini-pcb supposed to go into the modulator can? (after you rip its contents out). That would very much tidy up the wiring since all signals / power supply you need is right there.
I always do it like this:-
The brown wire goes into the RF modulator in a Spectrum style composite mod.
ZX80
ZX81 iss 1 (bugged ROM, kludge fix, normal, rebuilt)
TS 1000 iss 3, ZXPand AY and +, ZX8-CCB, ZX-KDLX & ChromaSCART
Tatung 81 + Wespi
TS 1500 & 2000
Spectrum 16k (iss 1 s/n 862)
Spectrum 48ks plus a DIVMMC future and SPECTRA
ZX81 iss 1 (bugged ROM, kludge fix, normal, rebuilt)
TS 1000 iss 3, ZXPand AY and +, ZX8-CCB, ZX-KDLX & ChromaSCART
Tatung 81 + Wespi
TS 1500 & 2000
Spectrum 16k (iss 1 s/n 862)
Spectrum 48ks plus a DIVMMC future and SPECTRA
Re: White screen and no cursor at all
Yeah that's right but if someday you want to go back and to get the RF signal it's easy and if do you rip the modulator circuit is impossible.RetroTechie wrote: ↑Sat Jun 08, 2019 8:38 pm Isn't that mini-pcb supposed to go into the modulator can? (after you rip its contents out). That would very much tidy up the wiring since all signals / power supply you need is right there.
That's why I installed the circuit in this way...
Re: White screen and no cursor at all
R1 is totally turned to the right then?Lardo Boffin wrote: ↑Sat Jun 08, 2019 8:58 pm Once you adjust the ZX8-CCB you should get a really good picture.
For later ULAs I start with this position and then fine tune:-
35DC1118-6135-4F8E-B637-8CCB59040850.jpeg
Yellow lines added for clarity.
Before adjusting I always take a photo of the current position. Very useful when it gets worse.
This is the recommended position when do you start the adjust but later it seems that should be turned to the left. Anyway, if do you have a good video signal it doesn't matter..