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Old 17th May 2021, 1:14 pm   #31
matspar
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Join Date: Aug 2009
Location: Portsmouth, Hampshire, UK.
Posts: 210
Default Re: Philips 663A combined radio/television 1948

Thanks Andy,

I have today replaced the last few capacitors in the line oscillator which I didn't previously have replacements for but no improvements were forthcoming and I'm still seeing the narrow raster.
I disconnected the scan coils temporarily to see if this would produce any more EHT, checked their continuity again and made sure their tag connections weren't dry jointed but again no change. Similarily replacing the pair of HVR2's and re-checking the newly restuffed visconols didn't throw up any faults.
Running the set with the EL38 removed will produce a perfect sawtooth (line drive) waveform but re-inserting it will then flatten the top.
DC resistances of the line transformer are very close to what is quoted in the Philips manual.
Occasionally when powering up from cold a full scan is visible for around 10-20 seconds which will then collapse.
So by the process of elimination it would seem that the flyback transformer is really the only thing left now, could it have intermittent shorted turn(s)?!

I will now explore if this can be rewound as I'm not going to give up on this beauty. The transformer is in a small square pitch filled box, so no idea how it is wound or what it looks like.
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Last edited by matspar; 17th May 2021 at 1:22 pm.
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