General Notes - Sinclair Microvision MTV1 Service Manual

GENERAL NOTES

This version of the Service Manual was compiled in December 2021, based squarely on the 2009
work of Peter Wisniewski, Steve Niechcial and Jon Evans, to whom I owe a huge debt of gratitude.
The Sinclair MTV1 (also written MTV-1) was designed and manufactured in the late 1970s. It was a
remarkable achievement, being the world's first 'pocketable' TV and also the world's first multi-
standard TV that would work just about anywhere. Unfortunately it proved to be a hard sell,
perhaps due to its cost. Production soon ceased, to be replaced by the MTV1B (MTV-1B), a cost-
reduced, single standard, UHF-only set that used a number of the same parts but retailed for half
the price of the MTV1.
The MTV1 had tuners for VHF (bands I and III) and UHF, sound demodulators for 4.5, 5.5 and
6MHz and would work with 50Hz or 60Hz TV systems. Power was supplied by a non-user-
replaceable integral 5V nickel-cadmium (Ni-Cd) rechargeable battery (comprising four AA cells
crammed into odd nooks and crannies).
At the time of writing, all Sinclair MTV1s are approaching 50 years of age. The fact that any of them
still work at all is remarkable. The internal Ni-Cd batteries have all long since ceased to function
and, in many cases, have leaked corrosive chemicals that have damaged the circuit board(s). In
some cases this can be sufficiently bad that the set is really a write-off, but in others the damage is
relatively minor. Either way, it is probably a good idea to remove the Ni-Cd batteries, handing them
with care and disposing of them according to local regulations, remembering that they contain toxic
cadmium. Although it is possible to replace the batteries with Ni-MH equivalents, this may not be a
wise action. The internal charging circuit is somewhat primitive – a string of resistors – and there is
no overcharge prevention mechanism. This was fine for Ni-Cd cells, which weren't particularly
troubled by prolonged overcharging, but Ni-MH cells are noticeably less forgiving in this respect.
Given that the MTV1 is a strictly analogue-only set, predating digital transmissions by decades,
there is very little chance of a refurbished set being taken out and used as originally intended, ie to
receive off-air signals while out and about.
The cramped construction necessitated by the small case meant that some of the clearances
between parts wasn't as good as one might prefer. Ordinary PVC insulating tape was used to
mitigate this and there is a surprising amount of it inside each set. Additionally, two areas received
plastic insulation sheet (notably beneath the EHT section) and this must be put back when
reassembling the set.
With the passage of time, the adhesive on the insulation tape has deteriorated. As the design
depends on its insulating properties it is sensible to renew it when refurbishing a set. You may want
®
to consider using Kapton or similar high performance tape instead of PVC.
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Sinclair MTV1 service manual V2.1