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Spectrum + 128K with no toroid
Posted: Mon Dec 02, 2019 11:36 pm
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.
Re: Spectrum + 128K with no toroid
Posted: Tue Dec 03, 2019 1:34 am
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
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.