Sinclair ZX80 / ZX81 / Z88 Forums

Here in Canada I've seen (and have examples of) three flavors. ZX81 with UHF modulator ZX81 with VHF modulator (later version) Timex-Sinclair 1000 with VHF modulator They were all intended for the market on this side of the pond, since the European folks use a different TV system. I don't think a un...

I'm in Canada and have a ZX81 (again not Timex) from early on. Unlike the Timex iterations, it has a UHF modulator.

Try reconnecting your antenna leads and looking for your signal on UHF. (Channel 38 rings a bell but I'm not certain of that.)

Thanks gozzo. This is so weird. I replaced both the 5V1 and 12V zener diodes--no difference. Then the voltages went south on me me. So I replaced the transistor. Voltages came back on line, but the behavior was unchanged. The -5V is pretty clean, but the +12V still had a fair amount of ripple, so I ...

This is kind of cool. Take a look at eBay item number 131154732817
More pictures in the listing. Someone has way too much time on their hands,...

The voltages are correct, and actually pretty close to the specified -5V, +5V, and +12V, which is amazing considering how they are obtained. (I do have 2 other packs with voltage problems that I have not been able to fix, despite my masochistic attempts to replace every associated part.) Here's some...

What kind of errors? details please ;) For example, Poke 0, Peek 4 (bit stuck on 1 at D2) Poke 255, Peek 127 (bit stuck on 0 at D7) Poke 255, Peek 254 (bit stuck on 0 at D0) etc. The edge connector is freshly tinned with a thin layer of solder and the pack has been reseated several times. I modifie...

My one surviving RAM pack has failed on me. So, thought I, this is an excellent opportunity to test Pokemon's ingeniously designed chip test circuit. It originally appeared in this thread: http://www.sinclairzxworld.com/viewtopic.php?f=7&t=923 but to save you time I will summarize and repost it here...

Actually it was the F type connector I was unsure of. I have a TV tuner PC card that has a different connector altogether for its antenna input, and I thought it might be a different European standard. (Turns out the card is PAL only as well. Anybody want it?) I haven't been to Europe since the 70's...

There also exists the opposite, an F-type female and RCA male adapter. See eBay item 270837508332 This has the advantage of letting you use a length of TV coax rather than an RCA cable, which I would imagine is far less lossy for the RF signal. I've been struggling get a good picture on modern TVs f...

I found with my unit that it would load ZX81 tapes with no issue, using the standard ROM. Programs SAVEd with the Lambda cannot be loaded back to the ZX81 however. It seems to output a tone instead of the initial silence, making the ZX81 unhappy.