48K dark output

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1024MAK
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Re: 48K dark output

Post by 1024MAK »

No, the socket is added to the modulator case by the manufacturer of the modulator.

Modulators have been obsolete for many, many years.

It may be possible to repair it. Which bit is iffy?

Mark
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roganjosh
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Re: 48K dark output

Post by roganjosh »

mtullock wrote: Wed Nov 08, 2023 10:21 pm Replaced both transistors. Did help a bit, but not massively. Also the socket for the RF now component cable is a bit "shoogly" and the cable connection is not reliable. I can't see a replacement part on retroleum as there is for power and audio. Anyone know of a suitable source?
I recently did s-video conversions on my Spectrums, which do away with the modulators, so I have some spare (used) modulators in my drawer. PM me if you want to send me a stamped self-addressed envelope and I can pop one in the post. Alternatively you could do an s-video conversion yourself, I used these: https://www.ebay.co.uk/itm/225523085460
Of course you need either a monitor capable of s-video or (e.g.) an s-video to HDMI converter. Options for the latter include Tendak & retrotink-2x Pro. If you want SCART you can look at an OSSC add-on unit (which can operate stand-alone). Check that you do order an s-video model as there are several types out there. I have all three and, frankly, the cheapest option (Tendak) provides a perfectly acceptable display to my eyes. Such a setup has the advantage of there being no dot crawl. All AFAIR provide an s-video lead.

Before doing that, though, it may be best to wait to see whether Mark thinks you need to get a brighter display with your existing setup first.

Alan
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1024MAK
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Re: 48K dark output

Post by 1024MAK »

Those S-Video boards look interesting. And on the GitHub page I get a credit :D

Mark
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redgatemodels
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Re: 48K dark output

Post by redgatemodels »

S Video is not as useful these days, now a simple hdmi mod that drops in the modulator space would be great
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1024MAK
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Re: 48K dark output

Post by 1024MAK »

HDMI is not simple. In fact, it’s very complex. That’s the problem.

Mark
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redgatemodels
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Re: 48K dark output

Post by redgatemodels »

1024MAK wrote: Sat Nov 11, 2023 5:38 pm HDMI is not simple. In fact, it’s very complex. That’s the problem.

Mark
I’ve got one of these, works very nicely.

https://www.ebay.co.uk/itm/125582260181

Maybe I should crack it open to see if the pcb will fit inside a Speccy
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1024MAK
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Re: 48K dark output

Post by 1024MAK »

Not wishing to dishearten you, but don't forget, the Speccy doesn't do a fully standard composite video signal. Rather than producing an interlaced video signal with all the correct timings, it actually just outputs one video field (with approximate timing) instead of even and odd video fields. Plus some converters/upscalers don't like the Speccy colour oscillator not being locked to the pixel clock (this design limitation is what causes colour bleed).

Be my guest to try it. If it does work for you, that's fine. I just want to put you in the picture that composite to HDMI converters/upscalers have been tried before...

Mark
ZX81 Variations
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ZX81 Video Transistor Buffer Amp

:!: Standby alert :!:
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Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb :!:
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