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Old 23rd Jun 2022, 11:25 am   #7
ben's Avatar
Join Date: Aug 2006
Location: Madrid, Spain / Wirral, UK
Posts: 6,843
Default Re: TELEFUNKEN 3309 (914 chassis) TV

Brief update.
I removed and cleaned the contacts on all the sub PCBs in the signal/RGB stages and touched up a few suspect joints. No effect. I have to say the standard of soldering in this set is first class. Especially when you consider it is very cramped in there, with a few components that run hot by nature, and will have been used in a hot environment for decades.

I discovered the chroma board had a small daughterboard rather crudely mounted to it, obviously modified at some later stage. Maybe for PAL? Since I picked up the set here in Madrid from a French ex-pat, that would make sense. There is one loose wire from it, which I have no idea where it was connected.

I tried adjusting the R,G and B drives and the blue had absolutely no effect, the red could be varied slightly. Disconnecting the green output still gave the green screen, this time with a few retrace lines. So it may be a HK short after all

Next I will try the old trick of isolating the heater winding (been a few years since I last did that!)
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