The Hi-Voltage Blues

[Raddion]

Hello everyone!

The cold weather is settling in here in Connecticut, so I've been finding time finally to tinker with my old '53 Philco... so far, I have removed and thoroughly cleaned both chassis and also replaced the tubes that either looked like toast or were missing caps, and I also replaced the slow blow fuse that looked like it let go sometime in the 1970's. I have not yet replaced any capacitors, although I know that will be necessary for a proper restore - I just would like to see some sign of life from the thing before laying out that cash and spending a week burning my fingers and inhaling solder smoke. The picture tube did test good using a multimeter...

I have not yet plugged it in to household current - I'm just not sure about the high voltage wire that clips into the little hole on the picture tube. Every other cathode ray television I ever saw had a suction cup type seal covering the connection to the picture tube, but this old Philco either is missing it or it never had one? When I clip the wire into the hole, there is a gap that looks like it would accomodate a seal, so I'd like to make sure before I plug it in and either ruin it or start shooting lightning all over my basement. Does anyone here know if the "Golden Grid" Philco is supposed to have a rubber seal at this connection to the CRT?

Thanks very much in advance, and if this has been asked before I'm sorry - I tried the search function last night but didn't come up with anything.

Raddion

[Zenith26kc20]

Not all sets had boots on the anode leads. If I remember, one of my Admirals has a clip only and it's lead is all original. Just be careful around the side of the CRT. They bite pretty good.

[N2IXK]

Many sets had just the bare metal clip. As long as there is no other wire or conductive metal within 3-4", it will work just fine. Keep the CRT bell area around the anode clean to prevent arcing/corona.

If you want to insulate it for improved safety, just salvage an HV lead and anode cap from a discarded BPC set or CRT computer monitor.

[jr_tech]

Neither of my '53 Philcos have a boot, and never did.

jr

[Raddion]

Thanks guys for helping me out, sounds like I'm ready to experiment. I will definitely be careful around the sides, thanks for the tip, I could have found that out the hard way.

jr tech, cool that you have a couple of '53's... Did you have to replace all your capacitors in your sets? I look into the back of this thing, and my mind whirls at the ingenuity and complexity involved in these "simple" designs. I can't wait to get a raster, hook up a VCR, and break out the old Lost In Space tapes!

If I power this thing up and then want to take the chassis back out for further reworking, do I have to discharge anything from the hi-voltage area before plucking that wire out of the CRT or is shutting the set down and unplugging good enough for safety?

I got popped once by a capacitor taking apart a TV when I was a teenager, I'll never forget the shock of it all.

[miniman82]

You must ground the anode wire to the chassis for several minutes before going near it, just discharging it once and digging in is asking for trouble. Ask me how I know, stray voltage will build up as it sits, then next thing you know you get whacked even though you thought you were being careful!

[Electronic M]

Some of those philcos used selenium rectifiers which will also need to be replaced for safety sake (they are sometimes still good, but when they fail they release stinky toxic selenium gas).

I had a 52' model which sort of worked on the original caps(I regard that a s a small miracle). It did produce a raster with video but the deflection circuits were so far off frequency and non-linear that it was unwatchable. At a bare minimum you will have to replace all the caps in the deflection circuits to get it semi safe for regular use. You will need to test all tubes with a proper tube tester, and I highly recommend testing the CRT on yours with a CRT tester before you bother restoring it; mine was barely usable. If you don't like the cost of the caps consider that you can recoup it by selling those bumblebee caps that look like over sized resistors....Guitar nuts pay big bucks for those caps whether or not they are good.

[jr_tech]

Originally Posted by Raddion

jr tech, cool that you have a couple of '53's... Did you have to replace all your capacitors in your sets?

No. I fall into the "troubleshoot and repair as necessary" school of thought, in regard to these sets, one of which has been in my wife's family since new.

http://www.videokarma.org/showpost.p...43&postcount=1

jr

[Raddion]

All this is great information, I am really learning on a fast curve here. Should I dare to plug this set in before finding and replacing the selenium rectifiers? Will my house smell like a giant fart for a month or something?

More research, I guess.

[N2IXK]

Failed selenium rectifiers not only smell like a really vicious fart, the fumes are pretty toxic, as well.

Seleniums are pretty much on my "replace as a matter of course" list. Modern silicon replacements cost a few pennies apiece.

[Electronic M]

I've always had the 'stones' to put any given set on a variac, and watch it for signs of trouble and life.

[Tubejunke]

Originally Posted by Raddion

The picture tube did test good using a multimeter...


Raddion

How did you test the C.R.T. with a V.O.M.? A wild guess would compel me to assume that you did a continuity test or resistance measurement at the heater pins. Anyway, someone else stated that you need a proper tube tester, and I think that at this stage that backing that statement up would be the best advice that I could give along with a grave need of a variable AC supply device be it a Variac or any other brand name as long as it does the job.

You do NOT want to introduce this or any other long dormant electronic device to full potential from the get go! If money or availability are issues, you can always wire a 100 Watt incandescent lamp in series with one side of the AC line in to the set and reduce the voltage to a much safer level.

And my opinion on capacitor replacement is that if you adhere to the last paragraph and the set had no major issues to begin with when it was in service, then you can often get enough performance to evaluate some key aspects and decide if you really want to take the leap of doing a "proper" restoration.

Good luck with the Philco, which by the way made my unrestored and working 56 that I have owned since the early 80s.

[Raddion]

Ok, I am going to try and resist plugging the old Philco in for now. I'm already on the hunt for a used variac, and if I can't get ahold of one sooner rather than later I'll give the light bulb method a try I guess. Is there a particular voltage that is recommended for initial power-up?
Yes that's correct, I only tested the heater circuit - but if I remember right that was supposed to be a pretty good sign for the CRT if it passed? I do have an old CRT Tester/Restorer that I scored at a flea market last year, but it probably needs to be restored itself.

Today is my birthday, and the best present I could get would be to see a snowy white raster on that picture tube!!!

[DavGoodlin]

I never saw a CRT tester like that but it is probably OK as it looks like a 70s model.

Those TVs normally draw 200 watts at 120 volts, so placing a 100-watt lamp in series will start out at less than 50 volts, likely showing very little action. This is a very useful technique on solid state TVs where there is need to know of a low-impedance fault (dead short) before moving on
If you were to place two 100 watt lamps in parallel, that would be more like 60+ volts and be more useful for taking some measurements to see if the rectifiers and filter capacitors are working.

Good Luck, you're on the right track being safe and cautious.

[Dangler]

Happy Birthday!