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Old 28th Aug 2019, 5:31 pm   #178
FERNSEH
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Join Date: Mar 2005
Location: Gateshead, Tyne and Wear, UK.
Posts: 6,339
Default Re: Baird T5 restoration project.

Hi John,
Although the cabinet the Baird T5 is not as well made as the contemporary EMI models the T5's electrical performance is as good or even better than the HMV models. The T5 cabinet is a bit flimsy compared with the solid and heavy EMI sets. And the Baird T5 has that big fifteen inch CRT.

Meanwhile my T23 is still giving problems. Glasnost: it turned out I'd connected the video lead to the wrong connector on the tube base. That's been put right and the video signal is now supplied to the CRT grid connector..
So there is now a picture on the screen, but the brightness control still doesn't work!
The oscilloscope proves that the tube grid voltage can be varied by the brightness control. However, it is not the sync tips that are setting the black level reference, the negative brightness control voltage is referencing to the peak whites of the video waveform. I'd say the DC restorer diode needs reversing so that it conducts on the sync tips.
I reckon the CRT will have to come out again so that the base connections can be checked again.

DFWB.

Last edited by FERNSEH; 28th Aug 2019 at 5:37 pm.
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