View Full Version : Just picked up a Predicta Debutante


Aperna1985
03-30-2018, 06:52 AM
I picked up a Predicta debutante the other day off eBay about 5 miles from my house. It think it was a UG-3408C model, the first part of the sticker is missing all I see is 8C. It has a 17 inch screen, and looks to have been black before the surface rust got to it. I took the CRT cover off to test the Picture tube, and in big letters someone wrote 6.3v and the tube has a sticker on it that says its a direct replacement for Philco picture tubes, requires no rewiring, then it gives multiple models and one of them is the original 17" Predicta 2.3v tube, and I can see in the black plastic on the back it actually says Philco. I didnt test it because I wasnt sure what plug to use. I have a B & K 465 and both plugs A and B fit. IN the setup guide most 17 inch tubes use plug B but the predicta 17 tube is plug A. Also I dont know what to set my G1 and 2 voltages to. Has anyone seen this type of tube before? I dont want to take the whole CRT Case apart if I dont have to, but from what I see I cant find any model numbers at all.

The other problem is the wire that goes from the flyback to the top of the vacuum tube next to it broke off. Is the flyback now ruined?

Aperna1985
03-30-2018, 06:55 AM
Here is some more pictures of the tube and also the warranty sticker but I can't make out the model #

bandersen
03-30-2018, 12:03 PM
If it says it requires no rewiring, use the tester settings for the original CRT 17DAP4 type but use a 6.3 volt filament voltage rather than 2.68.

2.3 volts was for the 21" CRTs.


If you are worried about using too high a filament voltage, start at 2.68 volts and if it barley glows, turn it up to 6.3.

No, the flyback isn't ruing. You just need to reattach the plate cap lead. Remove the remains of the old lead from the cap. Very carefully strip and tin the end of the wire and solder onto the cap.

The big concern is to not break the wire off from the flyback.

Aperna1985
03-30-2018, 02:42 PM
I guess the set saw some moisture because the part of the wire that was soldered to the cap was green... is it possible to replace that wire completely? Or if I have to cut it back a little to get good wire, what would be a good replacement so I can extend it? And can I use liquid electrical tape with rubber tape over it to seal my splice or is there a better choice?

StellarTV
03-30-2018, 03:12 PM
Some Predictas did use a 17DRP4 which had the 2.3 volt heater. It was advised that in order to use a 6.3v tube on an 10L43 or 11L43 chassis that a 5w resistor be bypassed -long off white box affair located on a terminal strip between the main circuit board and the IF strip.

Most often that green comes from offgassing of the plastic caused by decomposition and this interacts with the copper in the form of that green corrosion at the ends where exposed to the air. Heat quickens this process. A lot of old electronics which employ wiring with the same vinyl composition sheathing have this- as the wire is usually slimy or sticky feeling, if not mottled white and brittle, and I believe the Philco tends to suffer from the latter.

That plate cap connection is easily available. The wire attaches to a terminal strip inside the HV cage and is easily replaceable, wire and all.

bandersen
03-30-2018, 05:02 PM
17DRP4 is 2.68 volts. https://frank.pocnet.net/sheets/201/1/17DRP4.pdf

The 17" sets I've worked on had transformer taps for 2.68 volts as shown in the service literature. You could relocate the CRT filament wire from the 2.68 volt tap to the 6.3 volt tap easily.

StellarTV
03-30-2018, 06:16 PM
A trifling difference, but it is amazing what a difference the ~.3v makes on these heaters.

Aperna1985
03-31-2018, 07:41 AM
I tested it last night and the tube is very strong! So I definitely have a set worth building. Now, I have to try and fix that wire, and I'll swap in the 1G3GT from my Tandem and see if it powers up.

Aperna1985
04-02-2018, 07:01 AM
Yesterday before easter dinner I tried to solder the cap back on, but the wire is a little too short.
What gauge wire do I need, and if it's some kind of specialty wire, who is a good vendor?

Electronic M
04-02-2018, 12:05 PM
Anything with about the same insulation and conductor thickness will work. It is not critical.