Sinclair mtv1

[timmy]

Got this Sinclair mtv1 and I have perfect sound but no picture all I have is a bright screen and white diagonal lines left to right what may stop the pics from showing as far as maybe a vertical problem or horizontal or maybe something else. I have seen tube tvs do this but don’t know what the problem was. Is it possible bad agc can lose the picture but have good sound.

[jhalphen]

Hi to all,
Hi Timmy,

on the following thread on the UK-VRR forum (post #10) you will find 3 pdf files (photo) pertaining to the repair of the Sinclair MTV Series micro-TVs.
Files are too large for this forum.

https://www.vintage-radio.net/forum/...d.php?t=206856

The third one is the most complete (39 pages), recent & interesting, updated data Dec 2021.

Your TV's failure:
do you have a full screen raster or just one bright H line across screen?
If only one super-bright line, reduce brightness to avoid damaging the phosphor.

If you have a raster, the bright slanted lines are the H retrace, visible because brightness pot is set too high.

Can you get a picture?
i suppose you're feeding the set from a ATSC to analogue converter + a RF modulator.

Hope this helps,

Best Regards
jhalphen
Paris/France

[timmy]

Originally Posted by jhalphen

Hi to all,
Hi Timmy,

on the following thread on the UK-VRR forum (post #10) you will find 3 pdf files (photo) pertaining to the repair of the Sinclair MTV Series micro-TVs.
Files are too large for this forum.

https://www.vintage-radio.net/forum/...d.php?t=206856

The third one is the most complete (39 pages), recent & interesting, updated data Dec 2021.

Your TV's failure:
do you have a full screen raster or just one bright H line across screen?
If only one super-bright line, reduce brightness to avoid damaging the phosphor.

If you have a raster, the bright slanted lines are the H retrace, visible because brightness pot is set too high.

Can you get a picture?
i suppose you're feeding the set from a ATSC to analogue converter + a RF modulator.

Hope this helps,

Best Regards
jhalphen
Paris/France

Ok I got it working it turns out there were 2 caps that were bad a 1uf 50v was open and a 4.7uf 50v that tested at 30nf so I changed 3 1uf caps and the 4.7uf and it’s working fine so far now got to put new nicads in and make sure they are charging. These little sets are not easy to work on very tight inside but after seeing it work it’s all worth it. I forgot to mention that all these caps were on the power board and from what I have read the 1uf caps are prone to open in these sets.

[timmy]

Does anyone know how many ma to charge a 4.8v 900 ah nicad battery pack.

[Yamamaya42]

https://www.mat.uc.pt/~pedro/aeromod...s/techbat.html

[Pio1980]

NiCads are notorious for puking corrosive effluent into their containment, nickel metal hydride cells seem to do better.