1959 Philco Predicta holiday
 

I've been holding off restoring my blonde Philco holiday because I thought the 2.63v CRT was dead(21EAP4). I saw online from another restorer that 21DP4 crts were used in some models(6.3v). I figured I had nothing to lose as testing it at 2.63v tested bad and the filament seemed dim. So I tested it at 6.3v and it came up into the low, but good range after cooking awhile. I can't find any info on the CRT except the sticker attached below. If it were at 2.63v tube, wouldn't the filament have burned out quickly? Let me know your thoughts as if love to get this going. I've located a flyback I need, but I'm holding off purchasing it until I get the very info sorted out.

It is a 9L37 chassis.

Looks like someone wrote "21FD" on it. Was that you or was that already on it? 21FDP4 is the 6.3V replacement for the 21EAP4.

That was already on it. Good eye, I couldn't make out the first part of what was written in there!

The gold colored hardware has pitting throughout. Should I just get a brass/gold spray paint or leave it be and just clean it a little?

What modifications were made to accommodate the higher filament voltage in the replacement CRT?

They shorted out a section of the big filament dropper resistor. I suggest unjumpering since we typically have higher than 117 line voltages now that make up for the four volt difference. You don't want to shorten the life of the tubes by running them hot.

You need to short out the 8 ohm section of WR-3. Pins 5 and 7. That will give you the 6.3v

Shorting out that section reduces the overall resistance of the series filament string. The voltage drop across the CRT filament also depends on the AC line voltage. Again, I recommend you do NOT short out that section.

Back about 1963-65, I worked for a Philco dealer. We saw lots of Predictas come in for service. Maybe I'm imagining it, but I think there was an adapter that looked like a picture tube brightener that allowed you to install a 6.3 volt filament tube in place of the OEM 2.6 volt tube. Anybody seen one?

Have you taken a voltage reading on the picture tube filament if left at 2.63v?

No reason to in a series string model like the Holiday or Tandem since both CRTs run on 600mA. You might possibly use an adapter in one of the power transfomer models like the Princess or Siesta but it's also very easy to move the CRT filament lead from the 2.68 to the 6.3 tap on the power transformer.


Yes, I've done three Tandems, three Holidays and a Pedestal. All were around 6.3 VAC. These sets use a 600mA series filament string designed for 117 VAC. If you replace a filament rated for 2.35 V @ 600mA with one rated for 6.3 V @ 600mA, the difference is only 4 volts. If you power the set with around 121 VAC, you'll have around 600mA running through the filaments.

Also keep in mind that four volt difference is distributed across all the tube filaments. There's nothing magical about the CRT filament - it's just another resistive element in the string.

Checked all of the resistors and replaced the ones out of tolerance. Still have to order a 2.2meg replacement for one of them at 1 watt, I'm out. I cleaned the dirty pcb board and replaced as many of the caps as I had on hand. There's a couple newer replacements, but they were tacked on so I'll replace them with new ones and solder them correctly on the board. My flyback is in the mail to replaced the old one that is bad.

I'm surprised it's bad. I've worked on around 60 vintage TVs and have yet to find a bad flyback.

Yep, me too. I turned the set up slowly on a variac and it arcs and burns the phelonic board on the flyback. I hooked it to my flyback tester and it come up bad there two. The windings ohm out pretty close, but there must be a shirt somewhere? I've heard sometimes those phelonic boards become conductive? Long store short it burned cleaned through the board by the resistor mounted on it.