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FERNSEH · 22nd Apr 2015, 5:50 pm

The measured volts on the focus control slider is 1000V, that's OK.
The voltage on the slider of the brightness control is 252V irrespective of the contol setting. Refer to the attached circuit diagram. The brightness control is VR1. It's most likely that resistor R34 is open circuit or there's possibilty that a wire has become disconnected somewhere.The circuit diagram shown here is from the later production receivers which do not have the "Baird" valve.

DFWB.

22nd Apr 2015, 5:50 pm	#2
FERNSEH Dekatron Join Date: Mar 2005 Location: Gateshead, Tyne and Wear, UK. Posts: 7,444	Re: HMV 901 restoration. The measured volts on the focus control slider is 1000V, that's OK. The voltage on the slider of the brightness control is 252V irrespective of the contol setting. Refer to the attached circuit diagram. The brightness control is VR1. It's most likely that resistor R34 is open circuit or there's possibilty that a wire has become disconnected somewhere.The circuit diagram shown here is from the later production receivers which do not have the "Baird" valve. DFWB. Attached Thumbnails