Predica Princess Flyback Question - Printable Version
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Predica Princess Flyback Question - platinumbird55 - 09-20-2022
Hello,
I recently purchased a Predicta Princess from Craigslist. The set is in overall good condition but has some very questionable repairs from previous owner(s). I've removed the main board and replaced all the tube sockets, resistors, capacitors, and K networks. I also just replaced the vert linearity pot as I found it was destroyed internally. I've also tested the CRT and it still tests strong. Overall the restoration has taken some time but everything is looking good. This is my first tube tv restoration but I've restored several tube and solid state radios/receivers from the 40's - 70's
The only question I have is about the flyback transformer. From everything I've read the flyback is covered in thick wax-type material. The flyback in the Predicta I'm restoring just has a single wax ring around the external outmost portion. I'm not sure if the flyback looked like this originally or if the previous owner removed the wax-type material. (I attached a photo).
I'm contemplating just applying some corona dope to the exposed surface and attempting to power up the set. What are thoughts from the forum, should I attempt to do this fix, or cover the entire flyback in special “Sensor Safe” RTV silicone?
RE: Predica Princess Flyback Question - MrFixr55 - 09-20-2022
Hi PlatinumBird55,
Yes, a chunk of wax is missing. I would be very careful about RTV. The "vehicle" for many RTVs is acetic acid (hence the vinegar smell as it cures). Acetic acid is conductive. This Flyback likely develops about 16KV give or take. You must find a product that is HV rated and follow the instructions. HV rated Glyptol may not hurt but may not help. I don't think that the issue is arcing between windings as much as it is arcing from the outer ring (highest voltage) to nearby components. If you fire it up without doing anything to the flyback, do it on a dry day.
Definitely remove, inspect and clean the HV Rectifier cup.
The more antique radios and TVs I service, the more I should take before / after pics of parts after cleaning off the tar / nicotine from them, and use as a public service announcement against smoking.
RE: Predica Princess Flyback Question - GarySP - 09-20-2022
Hello PlatinumBird55, it appears that the wax was used as a fix agent to hold the flyback as wound. I've used corona dope on flybacks to help eliminate high frequency whine. It is used more for its' insulating qualities than rigidity. I don't think it will hurt anything and will insulate the winding. Take care and BE HEALTHY! Gary
RE: Predica Princess Flyback Question - platinumbird55 - 09-22-2022
Thank you @MrFixr55 and @GarySP for your responses! I'll give it some more thought and put together a game plan. Looking forward to having a working Predicta soon!
RE: Predica Princess Flyback Question - radiorich - 09-22-2022
Hello PlatinumBird55,
Good luck with your Flyback !
Sincerely Richard
RE: Predica Princess Flyback Question - Bob Andersen - 10-23-2022
That looks like a replacement flyback as the originals have a wider coil covered in black wax. Either way, corona dope is a great choice to seal, insulate and stabilize the coil. I just paint it on right over the existing wax and exposed windings.