Re: HMV 901 restoration.
The no vision fault turned out to be a badly seated MSP4 valve in the second RF amplifier stage. The attached picture shows two side by side test card images.
The line timebase is running too slow and will not lock into the 10,125c/s sync pulses. The timebase is running at 5,062.5 c/s.
it is possible that the resistor which is in series with the line hold control R22 (50,000ohms) has gone high value.
The frame sync is poor and it is well known that that these EMI sets have excellent frame sync lock. I'll check for the presence of sync pulses at the anode of V1, the frame sync separator.
Another fault to sort out is no sound, just a hiss. It is possible that the local oscillator is not working.
DFWB.
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