Spectrum + 128K with no toroid

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Lardo Boffin
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Joined: Sat Nov 26, 2016 2:42 am

Spectrum + 128K with no toroid

Post by Lardo Boffin »

Hi all

I recently bought a toastrack spectrum and after opening it was surprised to see no toroid. I have only seen the insides of 4 or 5 of these so not sure if this is a common thing?


It does not obviously look like it has been removed. Although there was a repair / warranty sticker on it (not details though).

It works fine apart from a slightly jumpy video on RGB SCART on one of my TVs (most are fine). Research suggests it may be a similar issue to the ghosting on the +3 (https://spectrumforeveryone.com/technic ... compliant/)

I have seen a few photos of them minus toroid on Spanish websites.
ZX81 iss 1 (bugged ROM, kludge fix, normal, rebuilt)
Iss 3 ZXVid
TS 1000 iss 3, ZXPand AY, ZX8-CCB, ZX-KDLX & ChromaSCART
TS 1500 & 2000
Spectrum 16k (iss 1 s/n 862)
Spectrum 48ks plus a DIVMMC future and SPECTRA
Spectrum +2a

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Re: Spectrum + 128K with no toroid

Post by 1024MAK »

The toroid is actually part of a filter circuit to suppress noise escaping on the power supply input. The toroid would have had two windings on it. Only fitted where deemed to be needed...

The 128k, +2, +2A, +2B, +3 etc were never designed to control the SCART signalling pins...

They work fine if your telly can be manually controlled by a remote control or menu option (like one of mine 8-) ).

Otherwise you need to provide a proper +12V and a higher current 1.5V to 3V (to feed 75Ω input impedance). Either from an external supply or by making changes to the computer and the DIN to SCART lead or both.


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