My first Tv set!

I have been working on tube radios for about 2 years now. I ran into a deal on a philco tv about a month ago, that I could not pass up. It is a philco model 6604-50. The only problem is that I can not find any info on this tv at all, let alone a schematic. Is there anyone who can help me out here? If needed I can provide a picture of the tv. It has a 24ADP4 picture tube in it. Riht now I have no brightness at all, and a very high pitch sound. If I unconnect the speaker, the sound goes away, and I have a mild hum. Any help is greatly needed. Thanks very much in advance. BEN

[Sandy G]

Welcome to AK, Ben ! A couple of pics of yr new-found baby would be GREAT...

[Tubejunke]

The "hum" is a classic indication of a failed capacitor. I do not know what you know about electronics so I will not go into all of the details about capacitors beyond the fact that most any very old tv's need them replaced. Not ALL will be BAD but it seems to be common belief that if they are not bad then they soon will be. It is debatable in my opinion. To me its relative to how much the tv will actually be used.

Your Philco probably has several common problems. I am a Philco fan and have a 56 21" table model myself. Very dependable and simple chassis.

I am still learning about electronics. I greatly thank you for the help. How do I go about checking the capacitors? I hope these are easyer to find then some parts. I searched 2 days for an ion trap magnet, and still have not had luck. Where is the best place to get them? Thanks again for the help. One more question that I forgot to post in the first one is: The socket on my picture tube is broken, I know how to replace it, But where can I find the replacement? Thanks everyone.

[Phil Nelson]

Originally Posted by runnerben

How do I go about checking the capacitors? I hope these are easyer to find then some parts.

This article has basic information about identifying and replacing capacitors:

http://antiqueradio.org/recap.htm

It primarily talks about radios, but the principles are the same for TVs.

This page has links to various TV restoration case studies, which may also be helpful:

http://antiqueradio.org/restoration.htm

Replace the electrolytic capacitors first. They are critical to the power supply, and it's pointless to try diagnosing other problems until you know the power supply is healthy.

NOTE: Tube TVs have much higher voltage than old radios. Use extreme care whenever the bare chassis is powered up. A h-v shock can knock you across the workshop or kill you.

I would also replace all of the paper (and plastic-coated paper) capacitors. To check one, you need to unsolder one end of the capacitor and use a tester that applies the correct working voltage. (Checking with an ohmmeter is fairly useless, and you can't tell anything by simply looking at the cap.) It's less work to simply replace the cap without testing.

The majority of them will be bad, anyway. You can save yourself time and aggravation by replacing them now, while the chassis is on your workbench. Do not replace ceramic or mica capacitors unless you have a specific reason to believe that one is bad.

I usually check all resistors 1 megohm and higher in value, and replace any that are more than about 20% off tolerance. Smaller resistors are left alone unless, again, there's a specific reason to think that one is bad.

Be patient. TVs are more complex than old radios. There are more things to check and replace. In some circuits, it's critical to use exactly the same values for replacements.

Not to be a wet blanket, but I would not attempt this project until you get your hands on the schematic. You can doublecheck the values of components against the schematic & parts list, and check off each component as you replace it. That could help you find your way back to Kansas if you make a wiring mistake somewhere along the line.

Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html

[Tubejunke]

There is a company that rebuilds crts called Hawkeye. I would give them a call as if nothing else they may have some old scrap jobs sitting around that people have abandoned or the tube was unrepairable. It is VERY common in most any "repair" business for people to leave their junk for you to warehouse or haul off. Also why pay the bill if you didn't get a working "repaired" set back? You get that a lot.

I am not in the business of Radio &Television repair but I am in the electric motor repair business. Its all the same..

Back to Hawkeye, if they don't have a few old traps laying around, or even stock them, then ask them if they would know a good resource. Really AudioKarma is a good resource. Somebody (if not me) will have an extra to give you for a song or free.

We need to find out what you have. Got a digital camera? We'd like to see your set. If not will you post the crt number/letter code. I will be able to tell you what type trap you need or any other specs on the tube if I get the ID.

[bgadow]

Phil suggested getting the schematic and while it isn't always a neccesity I think it is a good idea here. Many of the caps in these sets are color coded instead of marked with their ratings. They can be hard to decipher oftentimes.

Take your time-it can be hard to be patient since you are going to be anxious to see this going again-but there are lots of oppurtunities for mistakes. I can tell you from my experience that some of my toughest problems to diagnose were not due to failed components but due to my own negligence. Globs of solder that shorted something out, parts wired to the wrong place, etc.

An idea. If the base on the crt is broken, you might buy a picture tube booster on ebay and use the base from it. I haven't tried one, but it may work. It will have a plug and a socket on it. You need a plug for the base of the tube, not a socket. (Of course you knew this.)
Donald