[vcf-midatlantic] ZX81/TS1000 with a modern TV

Dave McGuire mcguire at neurotica.com
Mon May 23 23:23:56 UTC 2022

   Yes, but this is NTSC-modulated VHF RF.  Can current TVs receive 
that?  I was under the impression that they don't.  (I don't have one, 
no free time to waste)


On 5/23/22 19:06, Dean Notarnicola via vcf-midatlantic wrote:
> I’ve yet to find a TV that can’t do ATSC and NTSC.
> On Mon, May 23, 2022 at 6:26 PM Glenn Roberts via vcf-midatlantic <
> vcf-midatlantic at lists.vcfed.org> wrote:
>> I have no experience with Sinclair but didn’t they have a built-in RF
>> modulator? That would put out an old style UHF or VHF signal that a modern
>> digital TV can’t decode. I believe you’d need an older TV to test these…
>> Sent from my iPad
>>> On May 23, 2022, at 5:54 PM, Dean Notarnicola via vcf-midatlantic <
>> vcf-midatlantic at lists.vcfed.org> wrote:
>>> I’ve read that the ULA on some older TS and ZX units do not put out a
>> 100%
>>> proper NTSC signal, something do with the contrast. It may be that modern
>>> TVs have issues, but CRT tuners can deal with it. Considering they are
>> all
>>> demonstrating the same behavior, these units may be fine.
>>>> On Mon, May 23, 2022 at 4:32 PM Jeff S via vcf-midatlantic <
>>>> vcf-midatlantic at lists.vcfed.org> wrote:
>>>> The K cursor is normal, and standard. The ZX81 does not have any kind of
>>>> intro or status boot screen. If you're seeing the K, then unless there's
>>>> something wrong with the keyboard, you should be able to see any numbers
>>>> you type.
>>>> On Mon, May 23, 2022, 4:21 PM Bob Shuster via vcf-midatlantic <
>>>> vcf-midatlantic at lists.vcfed.org> wrote:
>>>>> So I have two (2) Sinclair ZX81s (US version - one is still an unbuilt
>>>>> kit), and three (3) Timex-Sinclair 1000s.  I’ve connected them to a TV
>>>>> using an RCA-coax adapter and tuned to the correct channel, but I get a
>>>>> grey screen with the “K” cursor visible.  I’m unable to get past this.
>>>>> This is for all four units.  They seem to tune in white momentarily
>> then
>>>>> switch to fuzzy grey - with the “K” still visible.  This was both on a
>>>>> large 4K OLED set and a small HD LED TV, and I suspect they are just
>> too
>>>>> new to deal with the monochrome signal.  I don’t have a CRT TV to test
>>>>> with, just old monitors (which of course don’t have antenna
>> connections.)
>>>>> Any advice?  I’m selling these, so I’m not getting into modding them,
>>>> just
>>>>> want to confirm they’re working properly.
>>>>> Bob Shuster

Dave McGuire, AK4HZ
New Kensington, PA

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