1959 Philco Predicta holiday

[bandersen]

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.

[oldtvsandtoy]

Originally Posted by bandersen

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.

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

[bandersen]

Originally Posted by Telecruiser

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?

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.

Originally Posted by oldtvsandtoy

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

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.

[Radiotronman]

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.