Philco 49-1240 horizontal (?) problem
 

Here's a new one on me. Looks like a strong wind is blowin' at the top of the screen!

http://antiqueradio.org/art/temp/Phi...irdTearing.jpg

Haven't had time to investigate causes yet. Just finished recapping and I'm taking a break for the evening.

It's almost like the vertical linearity is blowing up in the top couple of lines -- and the horizontal is flaking out, too. Despite what you might think at first glance, the whole image is stable.

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

I've seen an effect like that on other sets. The culprit was the free running horizontal oscillator being so far off, it took that long for it to lock every frame. Is there a hor. oscillator frequency adjustment on this chassis ? If so, try giving it a tweak.

Looks like horizontal tearing, if the picture is stable though it's probably just horiz AFC doing it's job. Do the horiz alignment procedure, if you already haven't.

We hear and obey. I haven't done any of that good stuff yet. It just seemed funny to have a picture that's so wrong, yet so stable.

Later,

Phil Nelson

The stability may be unique to the crosshatch pattern; normal video may not stay locked in. It looks like a nice bright, sharp picture, though. Nice going!

Just for kicks, I had also tried it with rabbit ears and the in-home modulator signal, which is weaker than the pattern generator signal. The horizontal behavior was much the same.

I'll haul out the Sams manual tomorrow and find all of the adjusters. I've been avoiding the Sams because it's not accurate for this model, but the Philco docs (athough accurate) only amount to a schematic and change/version notes.

Phil Nelson

I think I have the Riders service info for it. Chassis 49-1240 code 123 & 124 are covered in Vol #4. I can take a look over the weekend if that would help.

Sure, that would be great. The more docs the better.

I just looked at the Sams horizontal adjustment procedure, which looks thorough and logical. Except that it uses three adjusters -- locking trimmer, etc. -- which this model does not have. (I peeked underneath to make sure they hadn't been moved to other locations. Simply not there.)

Tweaking the horizontal frequency coil did fix the windblown tearing, but the locking range is awfully narrow. I guess it's just not the world's most sophisticated TV, which is fine. I can still work through the sweep sections and try to bring everything up to spec.

Phil "they can't all be DuMonts" Nelson

I'd be scoping the B+ sources, looking for ripple and noise, most likely coming from the Vertical sweep retrace.. Jack Darr had written something like this up in one of his articles, a capacitor with a high power factor was the culprit, as I recall..

Yah, I may find all kinds of ugly stuff when I hook up a scope. All I've done so far is recap it, so I am just beginning the project.

Speaking of noise and retrace, if you turn the brightness & contrast far enough to show the classic slanted retrace lines in the top, you also see this squiggle in the center, which seems to trail down from the tip of the lowest retrace line.

http://antiqueradio.org/art/temp/Phi...ceSquiggle.jpg

Kind of arty looking, but I guess I should get rid of it eventually.

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

I have a hunch that funny squiggle will go away when the other problem gets cured. Must be occurring when the horizontal oscillator goes out of lock or something.

I'd look at the sync stripper and the sync separater circuits. Weak tube, leaky caps, drifted resistor could do it.

Those lines look like the horizontal momentarily quit at the beginning of the vertical retrace.. The fact that the problem is solidly locked to the vertical makes me suspect you'll see a pretty sizable vertical sweep induced ripple on one of the supply lines..

Just returned from a little family vacation, so I haven't gotten any farther with this. Here's the Philco sweep schematic for what it's worth:

http://antiqueradio.org/art/Philco49...pSchematic.jpg

I'm hearing a rapid ticking from the chassis, seems about vertical speed. The HV cage has been cleaned and shows no signs of past arcing. No signs of arcing anywhere, in fact. I hope this does not mean a vertical transformer is funky . . . .

Tomorrow, maybe I can locate my favorite listening tube and try to locate the ticking source. Will fire up the scope, as well.

Again, I have replaced all paper & electrolytic caps, plus C508, C516 and C517 in this schematic. I measure 327vdc on the 320v line.

Phil Nelson

Grr. Using a listening tube, it seems the ticking (arcing) sound originates in the flyback. I don't own a flyback tester, but I suppose I can disconnect it and check the resistance of the windings.

Phil Nelson

I suspect you're hearing the horizontal starting/stopping from the problem induced by the vertical section. Again, the scope will prove this out.

Phil,
Before disconnecting the fly for continuity checks, just for the heck of it, check the HV secondary and see if it `might' be open DC-wise.
It's doubtful there's anything wrong with the primary windings since the sweep width and boost appear good.

OK, here is the LV power supply schematic and the remainder of the HV circuitry (my set has two 1B3GT in doubler configuration, not one as shown there).

http://antiqueradio.org/art/Philco49...ySchematic.jpg

The HV secondary is supposed to be 2.5 ohms and I measure 2.6, so that seems OK.

Pulling the caps from the 6BG6 HOT and 1B3GT rectifier, I measure 134.6 ohms on the top half of the flyback primary (should be 240 ohms) and 35.8 ohms on the bottom half (should be 40 ohms). Not so close, but I can reserve judgment for the moment.

Referring to the p-s schematic, I put the scope on two points: the output side of choke L101, which supplies ~160vdc from the 7Z4 LV rectifier, and the output side of choke L100, which supplies ~320vdc from the 5U4G LV rectifier.

The 160vdc supply looks smooth and stable.

The 320vdc supply is jittery, and the jitters change (along with the ticking sound) as you turn the vertical hold control, seen in these two photos:

http://antiqueradio.org/art/L100ChokeOutput01.jpg

http://antiqueradio.org/art/L100ChokeOutput02.jpg

So, it's sounding plausible that vertical noise is leaking into that 320vdc line. Referring to the sweep schematic, I see that one lead (red) of the vertical output transformer connects to that line. Possibly I could disconnect that lead and then see if the jitters go away . . . .

Phil Nelson

Don't you own one of the B&K 1076/1077 analyst series and don't they act as a flyback tester among other things?

Sure enough, the Kiver book says it can check for leakage and shorted turns. Can't hurt to try it out.

Phil Nelson

I went through my Riders and there are only two pages specific to the 49-1240 code 123. The rest they say is covered by the 49-1240 code 121 in Vol. 2.

I took a couple quick pictures of the two pages in Vol. 4 and the schematic in Vol. 2 and uploaded them here.

Let me know if the stuff I posted is what you need. There's about 50 pages of info in Vol. 2. I'm can scan it all for you, but it might take a couple days.

I also found this image of the control area which perfectly matches the channel plate on my 49-1040. Does your set have channel #1 ?
http://www.bobandersen.com/images/sc...20controls.jpg

Thanks, Bob. That schematic looks like the Philco schematic that I got from Cliff, with the addition of a bunch of test points (A, B, etc.). If those refer to scope waveforms, they would be good to have, but let me digest this material for a couple of days before you spend a lot of time scanning. I am already struggling to retain my sanity with two sets of docs (Sams & Philco) both marked up and cross-referenced with part numbers from the other set. If I add a third set and try to cross-reference those printouts to the others, the world might explode.

I keep thinking that I'm only about half an hour away from whipping this mutt into watchable condition, but that's probably a fantasy. I should just slow down and try to learn something :)

My tuner plate looks like the one pictured -- an eight-position tuner including Channel 1.

Phil Nelson

If you want to temporarily disable the vertical, just pull the vertical output tube. Be sure to turn down the brightness first. Looking at the scope, can't tell much without knowing the sensitivity (volts/div) it is set for.

Pulling that tube sounds easy. The volts/div was set to 2 volts/cm.

Thanks,

Phil Nelson

Well, if my 1077B is accurate, my flyback failed the shorted turns test with flying colors :(

Here, I'm checking the topmost winding on the flyback, which connects between the plate lead of the 6BG6 HOT and the plate lead of the first 1B3GT rectifier. The resistance of this winding is supposed to be 240 ohms; I measure 134.6 ohms.

Perhaps Moyer has a sub.

Phil Nelson

http://antiqueradio.org/art/Philco49...estFailure.jpg

I'd think that that much of shorting (almost half that winding) would kill or drastically reduce the horizontal width, and drastically reduce the very high voltage feeding the CRT. The manufacturer may have had (after the info publication) thicker wire used in that winding, making the resistance read lower.

Some corona dope might take care of the arcing you were hearing.

If the flyback was shorted, you'd have low HV and boost. Assuming a x10 probe, you've got 20v p-p on that B+ line, try pulling the vertical output tube, (brightness turned fully down) and scope the line again. Another quick and dirty check would be to set the scope for "line" sync, and adjust the vertical hold. If the scope pattern walks, it's caused by the vertical. C102 and C104 would be the prime suspects here.

My EICO 944's manual recomends pulling the HV rect. tube and other stuff connected to the fly as it can cause a false bad reading. Perhaps the B&K is sensitive to that as well...

Good point. Also, maybe you have a known good flyback lying around you could try testing with the 1077 ? Just to make sure it's working properly.

I have read that most ringers are so sensitive that the filament winding will cause a false 'bad' reading if the tube is left in, pulling the tubes seems logical.

I pulled the damper tube and repeated the flyback test (I also disconnected the HOT plate lead and HV rectifier plate lead as in the previous tests). Same result. It's possible my 1077B is not accurate. I haven't tried this feature before and I don't have any known-good flybacks lying around to check.

I looked again at the 320vdc supply line with the scope. Pulled the vertical output tube and turned brightness down. Same result. The jitters change when I turn the vertical hold control. I used 1x probe both times. The jittering is less pronounced with the vertical output tube absent, but still noticeable.

Capacitors C102 and C104 were previously replaced, along with all other electrolytics and paper caps. I suppose it's possible that one of those two is miswired or defective, although the supply voltages seem about right everywhere that I've checked. I'll keep poking around.

Phil Nelson

Phil, you need to pull the octal base(s) on the HV retifier(s) not the top lead. These testers can tell if the fillament is conected to it's single loose winding. To para phrase the manual on my 944....Disconnect the top leads on the HO tube and HV rect unplug and completely remove the HV rect tube form the set, and disconect all other wires going to the fly.....If the fly tests good you can then plug the HV rect into it's socket, and if the fly then tests bad with the HV rect in place then the fillament on the HV rect is good.

some testers (like mine) are sensitive enough to measure the short that the HV fillament causes on it's winding when connected!

I did pull all three tubes, but I didn't disconnect all wires from the flyback. The 1077B manual doesn't mention pulling tubes at all. It just says connect to the plate leads after pulling them off the HOT and rectifier tubes. Sometimes manuals don't tell the whole story, though.

I will disconnect it tomorrow and try again. Then I can take it apart and look for signs of arcing, maybe dab on some dope if that looks worthwhile.

Phil Nelson

I removed the flyback and got the same test result. Test lamp illuminated = fail.

http://antiqueradio.org/art/Philco49...stFailure2.jpg

This is the original flyback, part #32-8538, same as given in the Philco 49-1240 supplement. The supplement also includes this schematic for the HV output section, showing the two HV rectifiers.

http://antiqueradio.org/art/Philco49...tSchematic.jpg

I suddenly remembered that my restored RCA 721TCS chassis is sitting out, while waiting for its cabinet to be refinished. That flyback has no problems and it makes a wonderful picture. The 1077B test also said that flyback was bad (I removed the HOT, rectifier, and damper tubes for the test). Perhaps this tester simply isn't working right.

I cleaned the heck out of the flyback with isopropyl alcohol and examined it closely under strong light. No signs of arcing and I didn't observe any when running the set in total darkness, so corona dope doesn't seem appropriate. For all I know, this flyback is fine.

Phil Nelson

http://antiqueradio.org/art/Philco49...ontalFixed.jpg

Tom was right, the funny squiggle disappeared when I cured the baffling horizontal problem.

I finally trekked to the regional library and photocopied all of the material in Rider's, which is quite thorough and encouraged me to investigate things more methodically. Checked voltages in the sweep sections, checked all resistors and replaced a few outliers, replaced a few micas just for fun, scoped all the sweep test points and recorded my waveforms in photos.

So many things looked right on the money, yet the picture was so messed up. Why??

I decided to gather all my scattered notes and mark up a clean copy of the Rider's schematic to show all of my replacements and voltage & resistance readings. Then it jumped out -- the stupid wiring mistake! I should have my soldering license revoked :( I didn't keep detailed notes, but I think I made the boo-boo early on, before I had realized how far wrong the Sams material is.

Anyhow, the 49-1240 looks and sounds great, and now I can get back on script. The CRT is strong & bright, and the lack of a fine tuner doesn't seem to matter. I honestly hadn't expected much from this E-waste refugee, and I grumbled about the cramped layout along the way, but it performs pretty well.

When I fired up Gone With the Wind to take the customary screen shot of Scarlett O'Hara, my son groaned and demanded that I play something different for a change, so he's responsible for this closeup.

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

P.S. I think teevee was also right in surmising that the ticking sound was the horizontal stopping and starting. It disappeared the minute I fixed the boo-boo.

Congrads, Phil.:D What was/were the details of the booboo?

I had not kept up with this thread until today when I read about the miswire and that the set now works properly.
I have experience in attempting to test these Philco flybacks. It can't be done with any "flyback" tester.

Looking at your photo of the flyback out of the set I see it is constructed with a laminated core rather than a powered iron core which makes all the difference in the world.

The Q is much lower for all flybacks built with laminated cores. I found this out when I had to replace the flyback in the Philco set pictured in my avatar.

Long story short, the Philco flyback was OK, but the HV 500 pf cap would short intermittently when the picture went to a dark scene because the HV would rise and arc inside the cap. Replaced the cap and all is well.

Glad you got your Philco working. It looks great.

Cliff

Great job :thmbsp: Harryhausen never looked so good :yes:

I wonder if an EICO 944 flyback tester would work ? They have a specific mode for iron core vs. powdered core.

Next-door terminal syndrome, where you have a bunch of components crammed onto terminal strips. You're replacing a few components in a tightly packed area and then the doorbell rings or the dog knocks over a lamp. When you return, you solder a loose lead to the next-door terminal instead of the correct one.

The chassis is in the cabinet right now, so I can't check, but it was one of the small .1 caps (C511 or C512, probably C512) on the grid of the vertical output tube. The wrong connection tied it to C517, the 560pf cap on a plate of the horizontal AFC/oscillator tube.

Groan. Small wonder the vertical & horizontal signals were tripping over each other.

In hindsight, I should have double-checked my work before looking for fancier causes, but it wasn't completely wasted time, as I always learn something from these debugging sessions. Anything that sends me back to my old TV books is helpful in the long run. And now I'm confident there are no marginal components left in this TV's sweep sections.

Regarding flybacks, it's good to know that different types won't all test the same. My 721TCS also has a laminated core, so my 1077B is probably working after all, as long as I use it for the purpose intended.

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

Hah. So the horizontal was sorta squegging at the vertical rate, causing that squiggly retrace. :screwy::tongue: