Yesterday I picked up a Philco F4626M Miss America. My wife is out of town for a couple of days and we'll miss Valentine's Day together. To smooth the path for this new acquisition, I told her that this TV is a gift. Since it's hers, not mine, she's welcome to sell it if she thinks we don't have room, although it would look great alongside her Mid-Century Modern things. All I want is a chance to restore it and take photos for an article before she gets rid of it. I also found a Philco ad with the 1958 Miss America next to the TV in her gown and tiara.

Phil Nelson

http://antiqueradio.org/art/temp/PhilcoMissAmerica.jpg

very nice looking :yes:

Hopefully when she sees it, she will think it's too nice to get rid of. That one is on my short list of sets I'd like to have.

Nice set! Also a very nice shameless trick! :D
Hmmmm, thinking my wife might like a TNP Sharp for Valentines Day .
jr

1. Butter her up a little, tell her that when you heard it was a Miss America you immediately thought of her.

2. Point out that that big screen will be much easier on her beautiful eyes that look like a deep blue? lake on a moonlit night. (do NOT tell her it'll help reduce her crows feet!!)

3. Tell her you were going to get her a Vacuum Cleaner but thought this was better.

4. Post the set for sale in the Classifieds section. :lmao:

If all else fails hide a piece of jewelry inside the set and tell her the guy would only sell it as a package deal with the tv.

Or you can do your Jackie Gleason impression and tell her "I'm king of the castle and youre nothing....what I say goes!:D ...come to think of it,that usually didn't work too well for Ralph...

Nice, somewhat fancy for a set of that era.

Is it the CRT that is shattered, or just the cover glass? Sure hope you can fix it, since the rest of the set looks pristine.

Reflection of tripod?
jr

It's a tripod. It thought I was being clever by throwing a big black dropcloth on the floor to reduce glare. You can see part of the cloth below the TV. If I had slid it back about six feet, it would have worked better. Oh well, it wasn't a serious photo shoot, just a quick snapshot to email to my wife. She's happy with the deal, by the way.

Today I replaced the electrolytics in the cans and powered it up. Plenty of light on the screen and the audio's fine. Horizontal deflection's OK, but vertical only fills half the screen. Vertical tubes are good. I see about half a dozen bumblebees on the sweep board. Those will be the next to go!

Phil Nelson

Very interesting. I think possibly it's wearing an evening dress. :scratch2:

Your Black Panther has been getting quite the workout lately. ;)

Kevin

Actually, Phil, I'm guessing that you've been married as long as I have, and that your wife will find your "shameless trick" to be endearing. I'm in a similar situation--tomorrow I pick up 3 radios. One is a "gift," the second goes in my study and I pretend that it's been there for years, and the third stays hidden in the garage until the next time my wife goes to visit her sister.

3. Tell her you were going to get her a Vacuum Cleaner but thought this was better.


Reminds me of an old Mad Magizine article that had various cartoons describing situations "You know you've been married a long time when".. "Both of you think that a replacement hose for the vacuum cleaner is a great anniversary gift" and the cartoon shows the couple in a happy embrace with the hose by their side...

As for myself, I've yet to step into the beartrap of love...

"Honey, shouldn't we go out and get a flatscreen that would fit in that cabinet if you removed the CRT and the tuner section?" :scratch2: :D

We'll want to see pix of that TV in it's natural environment, alongside her Mid-Century Modern things, when you have it all fixed up. :thmbsp:

Or, "Honey, we're giving each other snow tires for Christmas."

That TV is the epitome of mid-century modern...she HAS to love it!!

Just remember, the more often you buy things while she's away the less likely she is to go and leave you alone. :yes:

A few caps later . . . .

http://antiqueradio.org/art/temp/PhilcoMissAmericaFirstImage.jpg

Even with a brightener, this CRT's about as weak as you can get and still make any sort of picture. The rest of the project should be straightforward. This chassis is a snap to work on compared to the behemoth DuMont I've been rassling around recently. And unlike a Predicta, the boards are easily accessible from underneath!

Can't spend any more time on it this morning. Gotta pick up my wife at the airport this afternoon. It will be fun to show it as a sorta-working set, not a pretty (but lifeless) decoration.

Phil Nelson

P.S. Ignore all the glare. If I want to take nice screen photos, I'll have to hang a big black dropcloth behind the camera, as well as cover the floor.

Love it!!

So....how did the reception go? Did she like it?

She likes it a lot. I've finished recapping except for one .15mfd/1KV cap (who has that sort of thing lying around?).

I found three of these black guys on the video board. Yet another flavor of molded paper cap with plastic skin, I guess. The video really perked up after I replaced 'em, anyhow.

http://antiqueradio.org/art/temp/MoldedPaperPCBoardCap.jpg

Phil Nelson

Miss America's almost ready to be seen in public, except for a faint vertical drive line in the place where those usually appear. (Look just to the right of Mickey Rourke's forehead).

http://antiqueradio.org/art/PhilcoF4626MDriveLine.jpg

From older sets, I'm used to having a drive adjuster (or something) you can tweak, but this TV has few adjusters.

Ideas? Horizontal stability is great, so there is no other reason to mess with horizontal circuits.

The schematic is at:

http://antiqueradio.org/art/temp/PhilcoF4626MSchematic.jpg

Regards,

Phil Nelson

In my marriage, I'm afraid my wife would see right through it, and be VERY upset. But it's a cool idea!

Charles

My wife's a bigger collector than I am, and crazy about 1950s stuff. This is a welcome change from stodgy old DuMonts. I don't think I could use the trick more than once, though. And I have already identified a less interesting TV to sell to make room for this one.

Phil Nelson

From older sets, I'm used to having a drive adjuster (or something) you can tweak, but this TV has few adjusters. Ideas?


I added a drive control to my CTC-9, using hints from the CTC-7 schematic. It worked fine, maybe you coul add the components from the 7's schematic? It's on the ETF site, page 13 of the manual.

Phil, happy she likes it! Handsome TV with a great picture. Need to get my wife in that kind of mode :yes:
Kevin

I added a drive control to my CTC-9
That's an idea. After working on it a little more, I'm not sure that's really a drive line. It floats back and forth as you turn the horizontal hold, and basically disappears if you set contrast & brightness so that the upper and lower bars are true black when you're watching a letterboxed movie.

I think I'll touch up the cabinet and just play it for a few hours. Sometimes you look so hard that you see problems that aren't really problems.

Phil Nelson

Phil,

Very nice. I am so glad that there are the few of us that see the value in restoring these pieces of our American Heritage...

Phil,
That's a beautiful Philco!
Glad to know your wife loved it...who couldn't?
You sure got it working quick too! Do you think it will be hard to find a good picture tube for this model?

Me likey VEDDY, VEDDY much !

After working on it a little more, I'm not sure that's really a drive line. It floats back and forth as you turn the horizontal hold, and basically disappears if you set contrast & brightness so that the upper and lower bars are true black when you're watching a letterboxed movie.

I suspect the line is due to either a sync overshoot or the color burst which is not being blanked on horizontal retrace. You can prove this by adjusting the Horizontal Hold while still in sync, so as the picture moves slightly to the right you will see the bar shift to the left. You may also be able to minimize it by adjusting the fine tuning so that the high video frequencies (picture detail) diminishes and the line will disappear.

Are you receiving the TV signal via cable or a DTV set top box? Do you see it on all channels?

Yes, if I move the horizontal hold left while retaining sync, the picture moves left very slightly, and so does the line. The line is also minimized when I adjust the fine tuning for less sharp detail.

When that photo was taken, I was receiving a broadcast from my in-house transmitter (Blonder-Tongue agile modulator) on rabbit ears. Haven't looked for the phantom line using another source yet, but I'll do so tomorrow.

Meanwhile, I'm glad I decided to pull the safety glass and do some cleaning. The inside of the glass was almost as grubby as the CRT face. I have never seen a screen & glass quite this dirty.

Phil Nelson

http://antiqueradio.org/art/PhilcoF4626MDirtyCRT.jpg

I've seen much worse, try cleaning a smoker's set. bleck.

Dang. After playing for a while, I heard arcing and the picture went nuts. I quickly powered down, then tried again in a few minutes with room dark and the HV cage open. After the set warmed up fully, I saw a two-inch spark shoot from the side of the flyback to the cage body.

There is freshly melted wax below the flyback.

Is it worth trying to recoat it with RTV, or should I assume it's shorted and look for a replacement?

Phil Nelson

Maybe there's a little too much current thru the flyback? That could melt some wax. And make for excessive HV? IIRC backing off on the drive may help, but the service notes should say what the current should be set to. I think you don't have a short in the flyback, or else the set wouldn't work as well as we see in the pictures, unless it got bad after the arcing. Some RTV should help, overcoating the existing wax "tire" on the high voltage secondary. But I'd check for carbon traces that may have formed in the wax.

Oh, I'm sure you cleaned inside there, so cobwebs and such should be gone.

It wasn't really dirty inside the cage, but I cleaned in there anyway. This set has no drive adjuster and the Sams manual says nothing about drive. I posted a link to the schematic earlier in this thread.

Phil Nelson

Here's the victim.

http://antiqueradio.org/art/PhilcoF4626MFlybackMelt.jpg

http://antiqueradio.org/art/PhilcoF4626MFlybackWax.jpg

Some of the layers under the doughnut had melted and sagged down so that you could just flick them off with a fingernail.

Should I try to melt off the old wax before recoating with RTV? Seems like I should at least reflow it with a heat gun so that it doesn't have big cracks.

The arc came out the side of the doughnut as seen in the second photo, going to the side of the cage. A very healthy spark! I'm not sure whether it came from the big crack seen in the first photo, or possibly from the nib where the rectifier lead enters the coil, since I only saw it for an instant.

If the cause of overheating is excessive HV, I'm not sure how to change that other than by modifying component values, as the set lacks a drive adjuster. After I noticed the vertical (drive?) line on the screen, I replaced the two 5% resistors (R83, R84) connected to the HOT input grid; both had drifted more than 20%.

My initial HV reading was a little low, about 14KV rather than the 16KV-18KV given in the schematic. That was before I recapped the sweep board and replaced a few resistors to address a vertical linearity problem. I hadn't tested the HV after that.

Unless someone has a better idea, I guess I'll recoat it, fire up the set again, and see what happens . . . .

Phil Nelson

Phil,
When it arced, was an RF arc (ie., hissy and sizzly sounding)? Or was it a loud, sharp "SNAP!"? If the latter, it is most likely rectified HV arcing through a pinhole in the 1B3 filament loop insulation.
Re. the drive line, did it change at all with the contrast setting?
Bill(oc)

Here's the victim.

http://antiqueradio.org/art/PhilcoF4626MFlybackMelt.jpg



Ouch! If that RTV doesn't do the trick, let us know the part numbers from SAMS. I just came across a box of 30 NOS Halldorson horizontal outputs and yokes, 1968 stock. There's a small chance.

Great job on getting the set going.

Kevin

The sound seemed more like a constant sizzling and the spark was a bright blue constant stream. I just cleaned the 1B3 filament loop and didn't see any gaping holes, although I suppose a tiny needle hole would be hard to spot.

The line definitely was minimized when I changed contrast & brightness to make the background truly black, although I'm not sure if that was due to the contrast setting alone.

Phil Nelson

The sound seemed more like a constant sizzling and the spark was a bright blue constant stream.
Yeah, that would definitely be coming from the 'tire' itself, not from the 1B3 filament loop which would register as a loud SNAP or a staccato series of snaps.

that thing is toast, sorry bro.

Phil, have you ohmed the flyback from HO plate cap the HV plate cap to see if it is still continuous? What is the Philco and cross part numbers for the flyback from Sams?

No continuity between the 1B3 rectifier cap and 6DQ6 HOT cap. Bad sign, I guess.

The Philco part number from Sams & the transformer frame is 32-8799-1. No equivalent numbers are listed in the other columns for Holldorson, etc.

Phil Nelson

Crosses to Thordarson Fly 265.

Kevin

Hmm. Looking more closely, I see that the wire from the coil to the HOT cap is actually two very thin wires, and one of them is broken where it comes out of the coil. From that broken end back to the 1B3 rectifier cap I measure 541 ohms. The schematic seems to indicate 530 ohms between those points.

I wonder if it's worth trying to fix that break. I'm not good at soldering hair-thin wires, but if I had to replace the flyback, there would be some of that, anyhow.

Phil Nelson

I wonder if it's worth trying to fix that break. I'm not good at soldering hair-thin wires, but if I had to replace the flyback, there would be some of that, anyhow.



Was that 541 ohms between the break and the 1B3, or you mean 541 ohms from the break to the HOT? 541 is close enough to 530.

Worth a try. Oh, and be sure that the new glob of solder has no pointy ends, but is rounded. Pointy ends may produce corona.

IIRC, solder iron heat and molten solder should burn off the enamel coating on the wire, if so, no need to scrape it.

Also crosses to Merit HVO-217. If I were you, Phil, I would look for a NOS replacement or a pull from some other predicta.

That looks bad, like a lot of Philco's from that era.

I'd try Moyers for one.

It might not hurt to melt all the old wax off and see what it looks like underneath but I'm betting on some turn to turn shorts, this is probably what was causing the drive line in the first place.

I had just finished removing the old wax and recoating it when John asked whether I had measured for continuity. It looked normal under the wax, without any obvious burned-looking holes on that side of the coil, but I suppose HV only needs the tiniest opening to escape.

I'll start with Moyers.

Thanks,

Phil Nelson

Out of curiosity, does anyone have a sense of what usually causes flybacks to fail?

I suppose overheating is never a good thing and it can readily lead to failure. But what's the typical scenario? A problem in some other circuit makes the flyback overheat and then croak? Or is there some internal factor (similar to old capacitors being imperfectly sealed against air/moisture) that means many of them are doomed to fail eventually, even if the rest of the TV works perfectly?

Just wondering . . . .

Phil Nelson

Besides too much current, likely age and insulation breakdown played a good role. That part of the circuit is a harsh environment for electrical components.

Keep an eye out for these Pomona Cathode Current Test Adaptors. They come with common cathode pins interrupted. Use an analog VOM to monitor current. I didn't have a clue what they were intended for until I started working on my first TV. :)

Kevin

Looks like a handy gadget. I'm often too lazy to unwire something to monitor current there unless I suspect there's a problem. I've also heard of using an HP millammeter (428B) with a clip-on probe that goes over a tube's cap lead, which sounds even easier. Of course, that would be yet another 50-lb instrument to find room for :)

Phil Nelson

Of course, that would be yet another 50-lb instrument to find room for :)


No doubt. :D

Now that you mention it, I wonder how one of those small clamp on amp meters would work that I see them at the home center. I think some of those can measure AC or DC amps. You wouldn't catch the screen current on the plate cap wire, but it would be a very close reference.

Kevin

Then there's this thingy that I picked up at a hamfest two weeks ago. It has a tube socket adapter to measure HOT cathode current in addition to its other functions
http://i1216.photobucket.com/albums/dd366/IsthmusTV/MoreEmerson637003.jpg

I haven't tried using it yet. I'd like to find some documentation on it first. I'm curious to know how it checks flybacks.

-Clark

Now that you mention it, I wonder how one of those small clamp on amp meters would work that I see them at the home center. I think some of those can measure AC or DC amps. You wouldn't catch the screen current on the plate cap wire, but it would be a very close reference.

Kevin

For sure the cheaper ones are just transformer coupled (the wire that it clamped over being 1 turn) so they would be AC only. The more expensive ones ($100-200) do have a "Hall effect" type of device and can measure DC. I have not seen one with better than 0.1 amp resolution...just not good enough.:no:

jr

jr, good point.

I think they are more aimed at electricians measuring up in the 10-100
amp range.

It would be pretty easy to make one of those Pomona dealies with a tube base and socket.

Kevin

For sure the cheaper ones are just transformer coupled (the wire that it clamped over being 1 turn) so they would be AC only. The more expensive ones ($100-200) do have a "Hall effect" type of device and can measure DC. I have not seen one with better than 0.1 amp resolution...just not good enough.:no:

jr

Well I could indeed be wrong about the lower limit... there seem to be some "small clamp" units that advertise AC and DC capability down to 1 mA!
http://www.amazon.com/AC-Amp-Clamp-Digital-Meter/dp/B0015PI7EA/ref=pd_sbs_auto_1
not affiliated,
jr

Add: While poking around on the 'zon, I came across an interesting device that might be useful for detecting potential flyback trouble spots:
http://www.amazon.com/Raytek-MT6-Non-contact-MiniTemp-Thermometer/dp/B000O80B5M/ref=sr_1_7?ie=UTF8&qid=1298418192&sr=8-7
Anybody here using something like that for TV work?
jr

Also crosses to Merit HVO-217. If I were you, Phil, I would look for a NOS replacement
Moyer had one in stock, so I ordered it.

Meanwhile, to satisfy my curiosity, I fixed the broken wire from the coil and gave the set a brief trial.

No sparks, and the picture had the same brightness as before. With a listening tube, however, I could hear faint ticking or sizzling noises seeming to come from the coil. Looking closely at the picture, I also saw very short, fleeting dashes (one scan line high) zipping horizontally across the screen. I suspect that the transformer does have internal shorts, as was suggested.

Earlier, the coil had taken several minutes to get hot enough to really misbehave. I didn't let it go that far tonight. While I wait for the new part, I'll power up the set just long enough to measure the HV level and the output tube's cathode current. If those are out of whack, I'd rather find out before I've installed a new flyback.

Phil Nelson

...While I wait for the new part, I'll power up the set just long enough to measure the HV level and the output tube's cathode current. If those are out of whack, I'd rather find out before I've installed a new flyback.
It'll be interesting to see what the before and after readings are. Interesting too will be to see if the new fly is same as the Predicta's. That is, the replacement consisting of only the primary windings and 'tire'. You have to reuse the whole frame and core and the paper spacers between the 'C' halves since they determine resonance.

however, I could hear faint ticking or sizzling noises seeming to come from the coil. Looking closely at the picture, I also saw very short, fleeting dashes (one scan line high) zipping horizontally across the screen. I suspect that the transformer does have internal shorts, as was suggested.



As you have ordered a replacement, you could risk a few experimental fixes on the old one. I've used runny epoxy to fill in small cracks of the plastic surface of more modern flybacks. And there's a product called "Corona Dope" I think intended for the purpose of painting old flybacks. That the stuff, when dry, has a higher dielectric constant than air. And not allow arcs to happen. That it wicks itself into the flyback windings to fill air gaps. Presumably the original coatings and insulation has dried out and cracked, creating air gaps. This assumes that there are in fact no shorts.

Yes, I removed the old wax and recoated the coil with black "sensor safe" RTV, and then fixed the broken wire from the coil to the HOT cap. No sparks, no corona. It makes a great picture. Listening with a tube, I can hear faint ticking or sizzling from the coil.

Making some quick measurements, I got -45V on pin 5 of the HOT and 165V on pin 4. Neither of those seems alarming. Disconnected the cathode lead at pin 8, but my DMM wouldn't give a current reading there, for some reason.

I've used corona dope before, and it's good stuff. I didn't have enough left in the little bottle for this whole coil, though.

Time to set this aside until the new flyback arrives, I think.

Phil Nelson

http://antiqueradio.org/art/PhilcoF4626MHVSchematicPartial.jpg

Hmm, maybe that fix worked after all. It's been playing continuously for hours with nary a blip. I turned off the set to feel the flyback and it's not even warm.

http://antiqueradio.org/art/PhilcoF4626MRepairedFlyback.jpg

http://antiqueradio.org/art/PhilcoF4626MRepairedFlyback2.jpg

Vertical linearity still needs improvement, but that's about all I've got left to fret over.

Phil Nelson

Picture looks super sharp from here. :thmbsp:

Kevin

Looking Good! :yes:
Did the ticking / dashed lines quit?
jr

I recommend Aervoe Industries Insulating Epoxy Coating for coating Flybacks and HV coils, perhaps prior to coating them with Wax or Silicone.

It has a rating of 2100 volts per Mil of thickness, probably well in excess of the voltage difference between individual turns of a Flyback. Also it's watery thin so it can flow deep into the windings and seal them.
http://www.aervoe.com/paints_coatings/Insulating-Epoxy-Coating.html

Hello Phil ,
what great set
If I marry my sweatie I know she would like that tv

No dashed lines, no ticking or sizzling. I wheeled it into my office and played it for six or seven hours, sitting two feet away from me. I haven't stuck a listening tube back into the HV cage, but when you turn the volume down all the way, it's as silent as any other tube TV.

I had actually given up on this flyback and just tried the repair out of curiosity. Good practice for a time when I might want to repair something that's not readily available.

Since I've already ordered a new transformer, I may as well install that and keep this one as an emergency spare.

An interesting experiment, anyhow. And now I won't be so nervous about putting a new flyback in this TV. If this funky old thing didn't go up in flames, I don't know why a new one would (knock on wood).

If I ever do another one, I'll check out that Aervoe stuff.

Phil Nelson

I guess I don't understand how the broken wire would have cooked the core? :scratch2: Was it the HV zapping outward from that brooken connection that melted all that insulation? Looking at the meltdown picture, I'd of guessed it heated from the inside out.

If it were mine, I'd leave the repaired old part in there and keep torturing it. :D

Kevin

Wow. Thought I had seen just about everything service-wise, but this is the very first 'Lazarus flyback'. :D
Regarding that DMM not reading cathode current, you probly need an analog meter there. Digital meters tend to balk or go nuts on anything with complex or high level waveforms.

if its working fine why not leave it be and keep the new as a spare?, dont kick over a rock just to see what crawls out..

I have a fly in an old maggie that works fine and make yours look mint by comparison.

Yah, who knows what really happened with that flyback. I know that I saw a big blue arc and a bunch of new melted wax, and I know that the TV works well now. The rest is all guesswork.

I dug out my little old dime-store analog meter and it pegged the needle in the 250ma scale, so I guess the current is higher than the 100-140ma given in the schematic (assuming that this 25-year old Radio Shack special is accurate). Not sure where to go with that, since the grid voltages on the HOT look normal, as noted earlier.

http://antiqueradio.org/art/temp/PhilcoF4626MSchematic.jpg

I'm a little peeved with Philco for using cheap sockets on the HOT and damper. Their terminals are above the chassis.

http://antiqueradio.org/art/PhilcoF4626MCheapSockets.jpg

When I began unsoldering the cathode lead, the terminal instantly snapped off. Altoid tins are made of better material. The pin socket is like a bent strip of tinfoil with holes -- not very practical to repair. I have wonderful new sockets in the parts chest, but they're a normal style with terminals on the bottom. The original sockets are wedged into tabbed holes in the chassis, so replacing a socket with a standard type is not a plug-n-play job. Meanwhile, the TV plays fine with a cathode lead soldered directly to the HOT pin, so I'm tempted to pretend that I never saw those oddball sockets.

Leaving the old fly in place is sounding better. Instead of looking for more trouble, I'll play the set for another long spell today and see how it holds up.

Regards,

Phil Nelson

yikes 240ma :thumbsdn:

you may want to try that with something else, Thats more than I get on most of the color sets that operate at 25kv.

A couple things I frequently do is add a cathode fuse (although that may or may not protect depending on how quickly it blows) and I add a B+ fuse right at the output from the diodes (if SS that is). The idea being it may save something in case of a runaway B+. I know its overkill but since parts are hard to come by, why not. the HOT cathode fuse makes for an easy check of currrent. Did you bypass the meter leads with a .1uf cap when reading the current?


but all that aside, if its operating and not too warm, then I would just leave it alone.

There aren't many "something else" choices around here. I have a 50-year old Triplett multimeter, a flea market item that seemed to work when I briefly tried it with voltage and resistance. If I can scrounge a pair of probes that fit, maybe it's worth a try.

I didn't know you're supposed to bypass the meter leads with a .1 uf cap <blush>. Do you mean connect the cap between the cathode and ground, and then touch the meter leads to the cap leads?

Phil Nelson

I dug out my little old dime-store analog meter and it pegged the needle in the 250ma scale, so I guess the current is higher than the 100-140ma given in the schematic (assuming that this 25-year old Radio Shack special is accurate)...



When I began unsoldering the cathode lead, the terminal instantly snapped off. ... The pin socket is like a bent strip of tinfoil with holes -- not very practical to repair. .... Meanwhile, the TV plays fine with a cathode lead soldered directly to the HOT pin, so I'm tempted to pretend that I never saw those oddball sockets.

Leaving the old fly in place is sounding better. Instead of looking for more trouble, I'll play the set for another long spell today and see how it holds up.
----
Vertical linearity still needs improvement, but that's about all I've got left to fret over.



It's ugly and crude, but it worked. However, it would bother me too. If you can get to those sockets easily, I see what looks like the metal of the pin and terminal metal in the rectangular slot halfway between the actual pin socket hole and where the terminal sticks out. Using a smaller soldering iron tip, you might be able to melt some solder to one side of the metal I see exposed in that rectangular slot, and if you can, connect that cathode lead to that point. Slightly less ugly. :yes:

Or as you said, just pretend it's not ugly. :thmbsp: And I'd just tag and leave the new flyback on the shelf, so you can break it out if the old one does die. Not borrow trouble.

Oh, you could test your rat shack meter with a resistor and a source of DC (ohms law) to see what 120ma looks like on it. Though it's not DC on a cathode lead on a HOT. As mentioned above, use the 0.1uf bypass cap on that cathode, close to the tube.

Back in the 70's I was in college (Syracuse University class of 78) and in a EE lab we built and played with el cheapo kit Radio Shack meters. One of the exercises was to show how the AC measurements were done by the meter, and that its circuit assumed sine waves only. Give it a square wave and the indication would be wrong. Found it recently, but the plastic became all crumbly, on the plastic knob shaft. Useless except as a souvenir of college days. With a sticker from a box of Raisin Bran at the time with the Sun logo saying that it belongs to WA2ISE. :D

As for vertical linearity, you probably already replaced all the paper caps, so check the resistors. Dirt on the circuit board might cause some leakage.

Fixing the socket terminal was a good idea. I got a wire through the side of the socket, wrapped it around the little holed piece on the inside and the old stub on the outside, and soldered. Left a pigtail until I'm done messing around in that area. It won't survive caveman yanking, but the original terminal wasn't that sturdy, either :)

http://antiqueradio.org/art/PhilcoF4626MSocketRepaired.jpg

With a .1 uf cap in place, I measured 118ma cathode current with the Triplett meter. That's the middle of the 100ma-140ma range given in the schematic. I'm going to quit stressing over this, since the voltages on the HOT and general performance are also normal.

The vertical (drive?) line definitely becomes more visible if you turn the fine tuner CW to the point where focus becomes too sharp and you start to see ghosting contrast lines on the sides of objects. If you back off on the finer tuner, it basically goes away. I'm crossing that off the problem list, too.

Re the linearity, I previously replaced three resistors on the sweep board (R65, R69, R70) and that improved it somewhat. I just replaced three more (R66, R67, R68) and it's about the same. Please don't tell me it's the vertical integrator K1; I have built replacement integrators before, but they're kind of a pain.

Thanks,

Phil Nelson

Looks good. I'd probably just solder the other end of that pigtail to the terminal of the other tube socket (gently!), maybe creating a loop with the old wire to hold the pigtail to the terminal when you solder.

As far as vertical linearity goes, did you replace the vert out tube's cathode bypass cap? I had one go bad, and IIRC with it bad I couldn't get reasonable linearity.

So how's it holding up? :scratch2: Hoping its :thmbsp:

Maybe this model Philco is picky about Vertical tubes like our Barber Pole models and you have to go through a bunch of 'em to find some that perform well enough to correct that linearity issue.

It's holding up so well that I have gone on to the next project. Miss America plays all day long to entertain me in the shop until we decide where to put the set.

The linearity is just bad enough to be annoying. I have replaced practically every resistor in the vertical section, even the two on pins 9-10-11 of the yoke socket.

Swapping tubes is a good idea. I tried subbing the 12AU7 but don't have a 6CM6 (vertical out) on hand. I went on a treasure hunt and found many odd & wonderful tubes -- why do I have two dozen 6BH6s? -- but no 6CM6 or equivalent. May as well order one.

I was a little disappointed in the bass response and even thought of hotwiring a new tone control. Then I put the back cover on and, duh, the bass sounds fine.

Phil Nelson

I could swear I have a 6CM6 in the garage, I'll go look.

Yes, if I move the horizontal hold left while retaining sync, the picture moves left very slightly, and so does the line. The line is also minimized when I adjust the fine tuning for less sharp detail.

When that photo was taken, I was receiving a broadcast from my in-house transmitter (Blonder-Tongue agile modulator) on rabbit ears. Haven't looked for the phantom line using another source yet, but I'll do so tomorrow.

Meanwhile, I'm glad I decided to pull the safety glass and do some cleaning. The inside of the glass was almost as grubby as the CRT face. I have never seen a screen & glass quite this dirty.

Phil Nelson

http://antiqueradio.org/art/PhilcoF4626MDirtyCRT.jpg

I wish I had a picture of the Zenith 16C21 I trashpicked as a teenager 31 years ago - it had an almost opaque coating of sepia cigarette "tar" almost 1/8" thick - took a whole roll of paper towels to wipe it off. That and replacing the 1K3 and it was as good as new - best low-VHF TV DX set I ever had!

I could swear I have a 6CM6 in the garage, I'll go look.
Want to trade for a dozen 6BH6? :)

Seriously, if you find one, send me a PM.

Phil Nelson

Too bad it's not 6CL6, I have a bunch of those.... Only one letter off. :D

Nostalgia Air lists 6DT5 and 6CZ5 as substitutes

Maybe this model Philco is picky about Vertical tubes like our Barber Pole models and you have to go through a bunch of 'em to find some that perform well enough to correct that linearity issue.
I tried a couple of new 6CM6 tubes and now I can get closer.

http://antiqueradio.org/art/PhilcoF4626MLinearityImproved.jpg

Re-centering the vertical also helps (duh). Strange yoke gizmo, by the way.

Horizontal linearity ain't perfect, but with no linearity adjuster I think I will call this good enough. The next project is already underway.

Here's the usual gabby article:

http://antiqueradio.org/PhilcoF4626MTelevision.htm

Thanks for the advice.

Phil Nelson

Didn't find that tube, BTW. Looks good to me!

.

Here's the usual gabby article:


Phil, your gabby articles are far and away the most entertaining, engaging and informative of any out there. I always settle into one of your resto sagas knowing it's gonna be enjoyable to the utmost.
Bill(oc)

indeed the gabbfest is good, as is the consistant style (tube layout etc..).

I have been using the cut off the can and leave the base intact approach lately as well on sets where I dont want to spend a lot of time on.

I use a bone saw style for the cutting, seem them on those late night infomercials, the receprocate and you can plunge cut direct into the can with very little access. A bit pricey though...but fast.

Would it hurt to add a 10 ohm resistor on the HOT cathode? It would make it easy to check cathode current using ohm's law, 100ma = 1v. FWIW I do this on each of the output tubes on all HI FI amp builds, makes bias checks easy.

Interesting idea. I have also heard of adding a 250ma fuse lamp there.

http://www.videokarma.org/archive/index.php/t-13637.html

The fuse adds protection and the lamp is a poor man's current meter -- adjust for lower brightness.

Phil Nelson

Interesting too will be to see if the new fly is same as the Predicta's. That is, the replacement consisting of only the primary windings and 'tire'. You have to reuse the whole frame and core and the paper spacers between the 'C' halves since they determine resonance.
I'm still debating whether to leave the repaired flyback alone (works fine, so far) or install the new one (hey, what else did I buy it for?).

This looks like a pretty complete replacement. It's physically smaller and it has different insulation. No wax -- yay!

http://antiqueradio.org/art/PhilcoF4626MNewFlyback.jpg

Phil Nelson

This looks like a pretty complete replacement. It's physically smaller and it has different insulation. No wax -- yay!
Hmm. Differnt supplier, evidently. Ours was the wax version and came sans the frame.
The ones for Predictas were the only replacement flybacks I ever saw supplied that way.
oc

I've heard the same thing from other sources about Predicta flybacks (you only got the windings for a replacement). I think Phil's set takes exception to what we have come to expect with the Predicta name (crappy construction) as it was a top of the line set for them at the time.

With a .1 uf cap in place, I measured 118ma cathode current with the Triplett meter. That's the middle of the 100ma-140ma range given in the schematic. I'm going to quit stressing over this, since the voltages on the HOT and general performance are also normal.
Speaking of current measurement, this week I got my hands on an HP 428B DC milliammeter, which gave the same reading as my old Triplett meter, so I guess the Triplett's good enough for government work.

Andy's method worked like a charm. Clip the 428B probe over the HOT lead and measure away. Easy as pie. On this set, the Width control affects the current directly, so I turned it down to around 100ma, which gives reasonable width & picture.

I got the 428B to use on my color roundies, but it has already earned back the few shekels I paid for it, and now I feel better about just letting this Philco play away. After warming up a couple of minutes, it looks fine without the CRT brightener, so I tossed that in a box. Who knows why they put on a brightener in the first place? Maybe that was a quicker solution than diagnosing some peskier issue.

Phil Nelson

Andy's method worked like a charm. Clip the 428B probe over the HOT lead and measure away. Easy as pie. On this set, the Width control affects the current directly, so I turned it down to around 100ma, which gives reasonable width & picture.


I missed something. What exactly was Andy's method?

Kevin

Sorry, the method is just what I said (only too briefly). The 428B is a DC milliammeter whose clip-on probe you can place around the HOT lead to measure the current. Andy C. has mentioned doing this before. I thought I had referenced that somewhere earlier in this thread, but maybe I just imagined that part.

Anyhow, it seems to work, and it's easier than lifting one end of the cathode lead to measure. Perfect for a lazy guy like me.

The manual (http://www.hparchive.com/Manuals/HP-428B-Manual.pdf) is at hparchive.com (http://www.hparchive.com/default.htm). Talk about your cosmic gizmo. Be the first kid on your block with a second harmonic flux-gate-type magnetometer probe!

Phil Nelson

http://antiqueradio.org/art/HP428BProbeOpen.jpg

...Be the first kid on your block with a second harmonic flux-gate-type magnetometer probe!
That sounds like sumpthin' out of 'Back to the Future'.


:D
oc

Ah... so it's a clamp on amp probe. For a minute there I thought you were just clipping the lead of a convention VOM over the HOT lead and measuring current. I thought maybe somehow with the HV it was jumping through the insulation. :D