Another National 505!

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A non-working one of these came up for under £20 (delivered) on eBay and I figured it would be good craic seeing if I could fix it and add a composite video input.

It's a slightly different model (on the right) with a toggle power switch instead of rotary, but apart from that looks identical.

I found a brilliant video on YouTube detailing how to add a composite video input to a 1977 Panasonic television which turned out to have a very similar circuit.

UPDATE (13/02/22) -

All that was needed to get this going again was to replace a fuse on the main board. The problem was that someone had soldered a replacement fuse into the holder at some point and it wasn't rated highly enough. I sorted out the holder and put a 1.6A fuse in and off it went. 

I removed the UHF module and battery wiring and started adding a composite video input to this one. Above is an initial test using a signal from my trusty (repaired!) DVD recorder, but some tweaking is still needed. 

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