Predicta Holiday restoration

[Reece]

Bob: look at Lowe's or = and get a push on / push off canopy switch, used in a lot of light fixtures. You should be able to rig that behind the control pretty easily.

[bandersen]

I found this push on/off switch at Menards. The throw is just about the same as the old one. I also sorta got the original switch working and got a tip about some NOS replacement switches. I try them all and go with whatever works best.

[wa2ise]

(picture of the back side of a module, with circuit board style traces with values printed on, seen in post #100)
One could get some of the larger surface mount resistors and mount them between those traces. And if the voltage requirements and tolerances are reasonable and compatible with surface mount capacitors, those too.

[bandersen]

Yes, I bet surface mount parts would work fine.

After replacing the bad tube sockets and re-installing the painted replica K-networks, I did a bit of rust removal and re-assembled the set. I'm happy to say, it's still working Next up, I'm going to tinker with using a capacitor in place of the series filament dropping resistor.

[wa2ise]

Originally Posted by bandersen

Next up, I'm going to tinker with using a capacitor in place of the series filament dropping resistor.

At my web page http://pw2.netcom.com/~wa2ise/radios/compaa3.html#hcap I have a DOS program http://pw2.netcom.com/~wa2ise/hv.exe and an Excel spreadsheet http://pw2.netcom.com/~wa2ise/heater.xls for calculating the capacitor.

[bandersen]

Thanks. I plugged in 125VAC @ 60Hz with a heater of 97 VAC @ 600mA and came up with about 20uF. Note that's with a replacement 6.3 VAC picture tube rather than the original 2.35 VAC one.

Success! I installed the Ametherm thermistor and a 20uF motor run cap. The power up surge current was about 870mA which quickly settled down to slightly under 600mA. That should help extend the life of the tubes and eliminated about 13 watts of waste heat. More importantly the set is still working fine.

I'll pop the plastic screen cover off and see if I can clean it up a bit.

[StellarTV]

This is definitely the most extensive electronic restoration on a Predicta I've ever seen. Great work!!

[bandersen]

Thanks! I figure if I explore all possibilities on this set, other Predictas will be a piece of cake.

The NOS power switch I ordered arrived today. Looks like a perfect match other than the color.


What's this 1.5M resistor doing on the contrast pot ? The schematic shows a 1M pot with no resistor.
I lifted one end and measured about 2.3M on the pot. Ah, that was put in parallel to drop it down closer to 1M. The pot has a Philco part # and looks original. Could they have fudged it in the factory


I carefully bent back the metal tabs and swapped in the switch. It's working fine

[ChrisW6ATV]

Nice work, and pictures.

[Kevin Kuehn]

Those rusty primer modules turned out great

I took ownership of a pedestal Predicta last weekend, with I believe the same chassis as the set you're working on. Never thought I'd own one of these weird looking TV's, but apparently nobody else around here likes blonde things.

[Phil Nelson]

That switch looks like a perfect fit. Where did you get it?

Phil Nelson

[Kevin Kuehn]

There's even a current production of that switch available, but it looks like the mounting tabs have been changed. May still work if you swap out the complete pot cover? But you need to buy the complete pot to get the switch.

http://www.newsensor.com/ProductHigh...aspx?ProId=826

[bandersen]

Originally Posted by Kevin Kuehn

Those rusty primer modules turned out great

I took ownership of a pedestal Predicta last weekend, with I believe the same chassis as the set you're working on. Never thought I'd own one of these weird looking TV's, but apparently nobody else around here likes blonde things.

Thanks. Nice score and, yes, I believe it is the same chassis. Phil restored one of those a while back.

Originally Posted by Phil Nelson

That switch looks like a perfect fit. Where did you get it?

Phil Nelson

ETF classifieds

Originally Posted by Kevin Kuehn

There's even a current production of that switch available, but it looks like the mounting tabs have been changed. May still work if you swap out the complete pot cover? But you need to buy the complete pot to get the switch.

http://www.newsensor.com/ProductHigh...aspx?ProId=826

I found a closeup on another site. They do look promising.



With the power resistors out of the way, I found a good spot to mount the filament cap and wired it in along with the 120 VAC LED pilot light.

I better stick a note inside the set to explain my changes or some poor future tech will be mighty confused

That wraps up the electrical restoration so I'll move on to cosmetic issues.

[Kevin Kuehn]

I have a few of those newer ones for guitar amp work, so I opened one up. Actuator look the same? They're stamped CTS Made in ROC.

[bandersen]

Hmm. No, not really. The Predicta shaft is hollow and fits over a piece of metal protruding from the switch. These still might work though.