Well, I did it. I really can't recall the last time I handed over cold, hard cash for an old TV set & it would probably be a long time until I do it again but I'm now the proud owner of a Philco TV-123. It sure doesn't look like much as it sits today but I expect, in time, for it to become a cornerstone of my (shrinking) collection. This was one of the few models on my bucket list.

This was one that Nick Williams found; aside from disassembly & the addition of some rare tubes it's "as found". I was a little taken aback at first when I saw it in pieces but I quickly saw this as a blessing: this makes it worlds easier to move and will allow me to address things in stages. The cabinet is pretty scruffy. I had the pleasure of meeting up with both Al Hagovsky & Nick (et al) and Al spoke highly of Howard's Restor-A-Finish; I plan on picking up a can and giving it a whirl. The best news is that the crt is a strong testing RCA 21AXP22A with a '57 date code. While it would have been neat to me to have an original Sylvania-built crt this is sure nothing to sneeze at.

The chassis looks very clean (though it smells like a mouse house!) Philco seemed to be going for some kind of record judging by the number of caps in this thing. Somebody in engineering must have got a free trip to Vegas from Sprague for specifying all those black beauties! I probably had 2/3 of what I needed on hand but still put in a generous order to Just Radios for the rest. The chassis is marked "Run 1" so pretty early, I guess. I haven't dug around for date codes beyond the crt. I know there were some factory authorized mods installed on some of these but this one appears fairly stock.

I expect this to take quite a while; I'll update the thread as I move along.

PS: If someone smarter than me can knows how to rotate the images, go at it. They're correct on my computer but that's the way they uploaded.

Congratulations. We can see the images well enough, but if you want them rotated, I will do it.

Well, I did it. I really can't recall the last time I handed over cold, hard cash for an old TV set & it would probably be a long time until I do it again but I'm now the proud owner of a Philco TV-123. It sure doesn't look like much as it sits today but I expect, in time, for it to become a cornerstone of my (shrinking) collection. This was one of the few models on my bucket list.

This was one that Nick Williams found; aside from disassembly & the addition of some rare tubes it's "as found". I was a little taken aback at first when I saw it in pieces but I quickly saw this as a blessing: this makes it worlds easier to move and will allow me to address things in stages. The cabinet is pretty scruffy. I had the pleasure of meeting up with both Al Hagovsky & Nick (et al) and Al spoke highly of Howard's Restor-A-Finish; I plan on picking up a can and giving it a whirl. The best news is that the crt is a strong testing RCA 21AXP22A with a '57 date code. While it would have been neat to me to have an original Sylvania-built crt this is sure nothing to sneeze at.

The chassis looks very clean (though it smells like a mouse house!) Philco seemed to be going for some kind of record judging by the number of caps in this thing. Somebody in engineering must have got a free trip to Vegas from Sprague for specifying all those black beauties! I probably had 2/3 of what I needed on hand but still put in a generous order to Just Radios for the rest. The chassis is marked "Run 1" so pretty early, I guess. I haven't dug around for date codes beyond the crt. I know there were some factory authorized mods installed on some of these but this one appears fairly stock.

I expect this to take quite a while; I'll update the thread as I move along.

PS: If someone smarter than me can knows how to rotate the images, go at it. They're correct on my computer but that's the way they uploaded.

As others have said, congratulations on finding this TV, as it is probably fairly rare. I'm sure once you have the set fully restored to as close to original as possible, you will enjoy it, even though you will have to use a converter box ahead of the tuner--unless, of course, you plan to watch only DVDs or VHS videos. Bear in mind, however, that since these early TVs were made long before VCRs were even thought of, you may have horizontal sync problems, the most noticable and the most severe of which may be horizontal pulling at the top of the picture.

BTW, I don't know what the point was of having color TV in the 1950s, as there couldn't have been that many color shows on the air at the time; moreover, most TV stations of that era were not equipped for color telecasting (and would not be until at earliest the 1960s), except perhaps for the stations in Chicago, New York and Los Angeles which were operated by the three (at the time) major television networks. NBC was the first American television network to broadcast 100 percent color programming, but that milestone wasn't reached until the mid-1960s. NBC preceded every color program from 1954 until 1975 with a full-color peacock spreading its feathers on the TV screen, with an announcer proclaiming "The following program is brought to you in living color on NBC."

ABC and CBS used similar color logos when they began color telecasting, some years after NBC did so; CBS' logo had the three letters "CBS" dropping down to the viewing area of TV screens, with the network's "eye" logo to the right, and the announcer would say "CBS presents this program in color." ABC's color logo was composed of the lower-case letters "ABC", superimposed on a large black dot on your TV screen and shown, of course, in color on color TVs. The announcement was "This is an ABC color presentation." Since color TV was so new at the time, these logos were not seen all that much since, as I mentioned, most TV programming, including network shows, was b&w; in the beginning, I am sure only very special programs were telecast in color.

Keep in mind that unless you fell into the ownership of one these early sets, you had to have been wealthy or have lots of cash you didn't know what to do with. The fact that there were few shows on made it even more impressive when you invited people over and see a show in color! After 1965 color tv become kind of ho-hum since the novelty and mystery was passed, then the floor gates opened and color tv became just another thing in your home.

From Jeffhs: " ABC and CBS used similar color logos when they began color telecasting, some years after NBC did so; CBS' logo had the three letters "CBS" dropping down to the viewing area of TV screens, with the network's "eye" logo to the right, and the announcer would say "CBS presents this program in color." ABC's color logo was composed of the lower-case letters "ABC", superimposed on a large black dot on your TV screen and shown, of course, in color on color TVs. The announcement was "This is an ABC color presentation." Since color TV was so new at the time, these logos were not seen all that much since, as I mentioned, most TV programming, including network shows, was b&w; in the beginning, I am sure only very special programs were telecast in color."

Jeffhs, You are correct as far as ABC color I.D.'s. NBC's 1st color logo 1954-56 was a color version of the NBC chimes. NBC's color peacock didn't arrive on scene until 1956. Started as a still slide, the animated peacock arrived just a bit later. CBS started w/there color logo for the field sequential system in 1951. In 1954 CBS used the CBS eye logo for their NTSC color & had several versions of that until the animated letters in the 60's.

would have been neat .. to have an original Sylvania-built crt


Were these Sylvania also designated 21AXP22A? Hard to believe they would/could duplicate RCA's mfg process?

I took a look at the schematic for this Philco and noticed something I had never seen previously. The filament windings for the two LV rectifiers (5V3 and 5U4) are center tapped and the B+ is taken from the center taps.

What is the purpose of taking the B+ from the center taps?

I took a look at the schematic for this Philco and noticed something I had never seen previously. The filament windings for the two LV rectifiers (5V3 and 5U4) are center tapped and the B+ is taken from the center taps.

What is the purpose of taking the B+ from the center taps?

Most likely to reduce hum pickup from the filament winding.

I took a look at the schematic for this Philco and noticed something I had never seen previously. The filament windings for the two LV rectifiers (5V3 and 5U4) are center tapped and the B+ is taken from the center taps.

What is the purpose of taking the B+ from the center taps?
They always did it that way when the rectifier tube socket was part of the transformer. It was easier for the transformer manufacturer to do it that way.
The Admiral 20Y1 and the Muntz chassis did it that way.

Congratulations Bryan, I was expecting you made getting this one a priority. Dave A has a 123 and I promised Id help find the cause of no HV. I do have the factory schematic and try to scan at 600dpi and email later this week.

My plan is to take the file to a blueprint place and make a poster of it before I look at Dave set. My eyes are not so great anymore and bright bench lights are a must-have too. With an RCA, I can do from memory but not such a unique chassis - a great project.

Congratulations Bryan, I was expecting you made getting this one a priority. Dave A has a 123 and I promised Id help find the cause of no HV. I do have the factory schematic and try to scan at 600dpi and email later this week.

My plan is to take the file to a blueprint place and make a poster of it before I look at Dave set. My eyes are not so great anymore and bright bench lights are a must-have too. With an RCA, I can do from memory but not such a unique chassis - a great project.

Please email a copy of the factory literature to the ETF. That type of documentation should be preserved/made available to the community.

Dave, I have a feeling I'll be calling on you for advice before it's over. Worst case, you'll have another 123 chassis on your doorstep :)

Meanwhile: the yoke has the typical rotted plastic shell. I was thinking today of something that has the potential to be a great solution-if I could find a defective 21" color yoke from another model, maybe I could transfer the plastic? I've taken yokes apart to junk them and sometimes it just involves removing a screw or two. I haven't compared the two styles side by side; who knows, maybe I have some oddball yoke around here that I could look at. If somebody has a dud sitting around, let me know.

If a 60's light plastic roundy yoke would work for you I have 2-3 spares so I could let one go for something like $10 plus shipping.

If a 60's light plastic roundy yoke would work for you I have 2-3 spares so I could let one go for something like $10 plus shipping.

Tom, I'm going to study it carefully and if I decide that option might work I'll send you a PM.

Let’s see pictures of the front of the cabinet. This is one of the more stylish of the early color sets! Fantastic find!!

DaveA's TV-123 was mine at one time, it has an interesting history. It was a bear to restore almost as hard as the Philco prototype color set I had. At least there was documentation available for the TV-123.
If you want to see the restoration I did on the 123 when I first got it and closeup pictures of the chassis and cabinet and picture go here:

http://www.myvintagetv.com/philco_tv123.htm


Chuck

Chuck, I remember seeing your 123 page-it was one of the reasons I wanted one of my own. I know I'll learn from you wrote.

Last night I dug out a big box up in the attic full of yokes; much to my surprise there is a used 21" color yoke (RCA) from the 60's! I thought I'd gotten rid of all the spares I had. It does appear that it could be a good donor for the rear plastic though I wonder if it might be close enough electrically to use the entire unit? That will come way down the road. For practice I've been recapping the Philco-built radio out of my Packard. It's percentage of Black Beauties was the same!

I'm A little confused. It looks like this chassis has almost all original parts. The photos of the picture from your sight look great. If this is the same set, how did it perform so well for you?

An update: I finished the radio I was working on so last night I drug the 123 chassis in and hoisted it up on the bench-no small feat! Tonight I did some cleaning and got a start on the long recapping job. Some observations:
1) I found the petrified remains of a mouse at the bottom corner, right up against the AC input :eek: Before it expired it ate about a third of a wax-paper capacitor (one of the few in this set). The good news is it didn't make too much of a mess.
2) This set uses the odd 6M3 damper with a top cap; Nick installed one, NOS, but where was the top lead? I was concerned thinking a wire might have been ripped from the flyback. Well, it turns out that somebody previously wired the socket for another tube type and they just cut the lead short and soldered it where needed. It should be fairly simple to rewire this back to where it was.
3) This uses a concentric horiz.center/vert.center control (2 watt/4 watt, 100 ohm each with 45 ohm center tap on the vertical). It was partially loose as found and trying to turn both pots tells me that both have turned to Crispy Critters inside. Hopefully the recap will take care of the cause; finding a decent replacement could be a challenge. Sams only lists the Philco pn (33-5546-66) no listing at Playthings of the Past. Most likely I'll just have to get creative.

Elsewhere under the chassis I found a small electrolytic with one lead disconnected. Adventures lie ahead! More photos soon.

Maybe try looking looking for that dual pot at Surplus Sales of Nebraska. I found an nos focus pot for my 1950 Dumont there.

Thanks for the tip on Surplus Sales of Nebraska; while they didn't list what I needed I did bookmark their page for future use.

I'm posting a couple more photos. So far, since I took this photo, I've shoehorned a few new electrolytics under there. They didn't waste any space when they built these.

Changing the paper caps on most Philcos of the era opens up space...I'd be tempted to do that first to make room for the lytics, or restuff the lytics if I were in your shoes.

Another update: I have most of the electrolytics replaced & a handful of the Black Beauties. The hardest part of the recapping is over. I took a little break this weekend & brought the cabinet in from the shed; it needed some bracing replaced in the back and a good vacuuming. I then treated it to some Howard's Restor-a-Finish which I quickly learned is an outstanding product. I never thought this set would come out so well. I have some minor touch-up to do and then a good coat of wax-it won't be perfect by any means but it will be better than half my existing collection!

Then I decided to mount the crt. I'd been dreading this since it was all apart (the crt, mounting frame including yoke, the 2-piece rubber insulator and the purity magnet ring). I wasn't the one who took it apart which made it that much more of a challenge but it actually came together really well. At one point, while tightening one of the retaining clamps for the mounting frame, the screw wasn't in far enough to grab and it let go with a BANG! Made my heart skip a beat-I was very well aware of the damage that could occur to my ego, my wallet and my body, should I mess up while tightening things down!

So, it's starting to look like a TV again. I'll really have to fight off the urge to try a power-up prior to finishing the recap. I know, though, that the chances of much of the circuit working with all those Black Beauties in place is extremely slim. Anyway, more updates to come.

What a fine looking unique color set! I wonder why Philco, Sylvania, Silvertone, Admiral , Motorola, PB and others took about 4 years off making color sets after introducing their 1957 models???

Just think of all the models that could have been, even if CTC7-10 RCA clones...:sigh:

What a fine looking unique color set! I wonder why Philco, Sylvania, Silvertone, Admiral , Motorola, PB and others took about 4 years off making color sets after introducing their 1957 models???

Just think of all the models that could have been, even if CTC7-10 RCA clones...:sigh:

Dave,

All those manufacturers who followed RCA Victor in it's big 1956-57 push to market color tv failed miserably. Even giant RCA, who sold the majority of color sets in this period, was very disappointed. The prices were to high and the color programming was to little to justify purchasing this luxury item. Pretty much only RCA with it's NBC network continued to offer color sets & programming in any significant way. In 1962 some of these companies choose to re-enter the color tv market. It still took another 3 or 4 years for the average buyer to come round.

-Steve D.

Also there was a recession around 1958. That probably did not help either.

[QUOTE=bgadow;3203700]Another update: I have most of the electrolytics replaced & a handful of the Black Beauties. The hardest part of the recapping is over. I took a little break this weekend & brought the cabinet in from the shed; it needed some bracing replaced in the back and a good vacuuming. I then treated it to some Howard's Restor-a-Finish which I quickly learned is an outstanding product. I never thought this set would come out so well. I have some minor touch-up to do and then a good coat of wax-it won't be perfect by any means but it will be better than half my existing collection!

Then I decided to mount the crt. I'd been dreading this since it was all apart (the crt, mounting frame including yoke, the 2-piece rubber insulator and the purity magnet ring). I wasn't the one who took it apart which made it that much more of a challenge but it actually came together really well. At one point, while tightening one of the retaining clamps for the mounting frame, the screw wasn't in far enough to grab and it let go with a BANG! Made my heart skip a beat-I was very well aware of the damage that could occur to my ego, my wallet and my body, should I mess up while tightening things down!

So, it's starting to look like a TV again. I'll really have to fight off the urge to try a power-up prior to finishing the recap. I know, though, that the chances of much of the circuit working with all those Black Beauties in place is extremely slim. Anyway, more updates to come.[/QUOTE

Bryan, I hope that "BANG" you heard had nothing to do with the CRT. Where did the noise originate? My best guess is an HV arc from the CRT bell to ground.

At one point, while tightening one of the retaining clamps for the mounting frame, the screw wasn't in far enough to grab and it let go with a BANG!

Bryan, I hope that "BANG" you heard had nothing to do with the CRT. Where did the noise originate? My best guess is an HV arc from the CRT bell to ground.

?..

?..

I don't think the CRT was used since the set was disassembled. They don't hold a charge that long.
It was probably a plastic insulator or other part. :scratch2:

I don't think the CRT was used since the set was disassembled. They don't hold a charge that long.
It was probably a plastic insulator or other part. :scratch2:

I was just pointing out that Bryan specifically stated that "At one point, while tightening one of the retaining clamps for the mounting frame, the screw wasn't in far enough to grab and it let go with a BANG!." ;)

Over the years I've had a recurring bad dream where I come close to damaging the neck on the 21AXP22 in my CTC-5. Hopefully I won't have twice as many dreams now!

I was out of town for a few days but spent this rainy afternoon finishing the electolytics then started going section by section through the BB's. I've completed most of the LV, HV & horizontal. I did a brief filament-only power up with the LV rectifiers removed, just to check for any drama (there was none). I may allow myself a full-power up soon. I did goof one thing up today: while moving the chassis around on the bench I put too much pressure on one of the IF cans and bent it right over, snapping a couple wires inside. I couldn't find one end of one of them at all. The good news: it's a common part and a quick check of my big old coil box turned up 3 or 4 exact replacements in a few minutes. Hopefully the pain of having to deal with touching up the alignment will keep me from being so clumsy next time! It is HEAVY and rather awkward.

I notice that the fourth photo shows a tag on the chassis: ".75 AMP 250V".

This would be a rarity indeed - a 250V power supply when the only country with a color TV infrastructure was entirely 120V.

Was this built as a demonstration or test set to be used abroad?

Or perhaps this is just the spec of a fuse in the set? :scratch2:

jr

edit add: Sams shows a 3/4A 250V fuse as "M3", in the 240 Volt supply.

I notice that the fourth photo shows a tag on the chassis: ".75 AMP 250V".

This would be a rarity indeed - a 250V power supply when the only country with a color TV infrastructure was entirely 120V.

Was this built as a demonstration or test set to be used abroad?

Probably a 120V set with a 250V spec fuse. That could be the B+ voltage for a fused B+ line...Or it could be that Philco recognized the voltage spec of a fuse if of little consequence and it is the current rating of the fuse that matters.

Funny that fuses would get mentioned-get a load of this:
I tested the fuses and they were all fine, which was encouraging. I did power the set up briefly only to find a light show inside the 5U4-whoops! While studying the schematic I was trying to figure out why no fuses blew. Well...somebody long, long ago (they were covered with a thick layer of dust) replaced 2 of the three with 2 amp fuses and the third with 1.5 amp! Yep, well, think of the cold, hard cash they saved on all those fuses they once had to buy!

I have a handy dandy Sencore "Fuse Safe" circuit tester which clips in place of a fuse & has a meter to test current draw. It's the HV circuit that's causing issues. It took me some digging to figure out which circuit due to some confusion: Sams has the diagram mislabeled on their drawing as to which is which, plus there seem to have been some running changes as to what Philco specified for each one. I'm not the best diagnostician but I'll pluck away at it...if I keep disconnecting stuff I'm bound to figure it out! Oh, one more thing-when I powered up I let a nice puff of smoke (and a sharp bang) out of something. I was quite concerned, but less so after I spotted the culprit. It seems that yours truly, in a boneheaded move, picked up a 10v capacitor and wired it in where a 50v (IIRC) was called for. Poor little thing didn't stand a chance!

I notice that the fourth photo shows a tag on the chassis: ".75 AMP 250V".

This would be a rarity indeed - a 250V power supply when the only country with a color TV infrastructure was entirely 120V.

Was this built as a demonstration or test set to be used abroad?

.75 amp 250v fuses are generally used for the horizontal sweep B supply. I do not think it has any reference to the a.c. input.

I notice that the fourth photo shows a tag on the chassis: ".75 AMP 250V".

This would be a rarity indeed - a 250V power supply when the only country with a color TV infrastructure was entirely 120V.

Was this built as a demonstration or test set to be used abroad?
First of all: The set draws a lot a lot more primary current than .75 amp. At the time all low current fuses were rated at 250volts.
Fuses were designed for fault current as well as overcurrent protection. The line fuse, if used is somewhere around 8 amp, 125 volts, 125% of run current.
Fuses have changed drastically over the last 20 or 30 years regarding fault current. All fuses 10 amp and higher in the 3AG size are either porcelain tube or sand filled.

The thread has been cleaned up. Let's try to keep the discussion limited to Bryan's Philco restoration going forward. The set was sold, the buyer and seller both seem to be happy with the sale, it's done.

Time for another update: there were some delays as I was out of town for a week on vacation, but I've been trying to tinker on the set for an hour or so each night. I've been scratching my head a lot, trying to figure out what was causing this large current draw in the horiz.limiting/damper circuit. I knew that, like all problems, the root cause was something simple. Finally, tonight, I stumbled upon it. I mentioned earlier that someone long ago had re-wired the set to use a 6AU4 damper rather than the oddball 6M3. I wired it back to original. I noticed that the filament wasn't lit and that's when I realized there was no ground to pin 2, an easy fix. For some reason it didn't occur to me to look closer-yep, they had simply moved the wire to pin 7 (correct for the 6AU4) and I totally ignored it. Internally in the 6M3 that's connected to pins 3 & 5...and the plate. So, yeah, I guess grounding the plate would cause that draw! The weird thing is that I'm certain I had yanked the tube and it didn't alleviate the problem-I don't understand how it couldn't. The good news is that the draw is gone.

I decided to do another quick and dirty power up with everything connected. While it would have been great to see "first light", what I did find were a few more things to troubleshoot: there is a 400mfd/50v cap (positive to ground) in the -25v circuit that blew. The purity circuit taps into this, among other things. I haven't replaced all the Black Beauties in that circuit so it could be as simple as that. And then, I briefly had some HV (I could hear it, smell the ozone, and there was a little snap-crackle-pop action going on) but then I lost it. No red plating of the horiz output; no raster, either. I'm not too concerned about it yet. All part of the "fun"!

Another little update, and a question. I'm down to just a handful of Black Beauties to replace. In between that I've been trying to troubleshoot the HV issue. Right now I'm only getting about 5kv, and that's with the HO being driven with a substitution box. I need to figure the disconnect between horiz osc and horiz output. Tonight after replacing an out-of-spec 5w resistor I powered it up and noticed one of the 3A2's was faintly glowing red pointing to a bad doorknob cap which I know others have had trouble with. (the set has 4 of 'em) That particular one is 1000mmf at 15kv. The closest I had on hand was 500mmf so I threw it in there and was rewarded with the sound of some sharp crackles but no red plate...and no change in HV. I'll keep digging, and learning (which is a lot of what this is all about). My questions: how close in capacitance rating do I need to be for this application, percentage wise? And, I've seen some 1000uf 15kv disc caps that were a lot less expensive. Would they work in this application?

The set uses a doubler circuit in the HV so the doorknob caps need to be replaced with other doorknobs of the same rated capacitance and same or higher voltage. If the capacitance is not the same the HV may drop or increase. The original part probably has a tolerance rating. The only way you can use a part of another value is if that part is within tolerance of the original and the replacement has a tighter tolerance whose bounds do not fall outside the bounds of the original. most doorknobs were made in the time around when these sets were in use so closer tolerance parts that fit in bounds are probably harder to find than the right part.

Doorknob style capacitors rated between 40 kV and 175 kV or so are still available for use in medical equipment. They can be found on Mouser, etc. 40 kV, the lowest commonly available size, is overkill for all but the largest theater projection sets.

They're usually in the values we need (500-1500 pF) and the tolerances are no worse than the OEM part would have had when new.

They're rather pricey, running between $30 on the absolute low end and $100+ on the high end, depending on brand, voltage rating, and capacitance. Still, I'd rather spend $400 replacing leaky doorknobs than have a dark set with a bad flyback from the additional load placed on it.

Well, I know that thousands of followers are waiting on the edge of their seats for an update...

Buying doorknob caps can be confusing. I started with our friends at Moyers. They have some NOS 500pf but not the others (which were never a common need in TV repair circles). I checked out ebay, some Chinese suppliers, Fair Radio, Surplus Sales of Nebraska & numerous sites that cater to the Tesla coil crowd. I didn't really want to go used (I already HAVE used!) and that's mostly what they offer, and not in the exact values I wanted. The Chinese outlets were tempting with the expected low prices but I just didn't trust them. I ended up printing off pages from Vishay-Sprague & MuRata catalogs and trying to find what I needed in stock & benman94 steered me right. It wasn't real easy to find them without part numbers in hand. I ended up with a pair of MuRata 1000pf 20kv & a 2000pf 40kv. (For now I'm letting the 500pf be as I actually have a handful of them used, and can always grab one from Moyers-the only way I could find one from Mouser was at about the 40kv level, at a hefty price.)

The 1000's can be had with "inch" threads; the originals had studs made on them. I just cut down some screws with the proper threads and used them. They fit just fine (the new ones are a little taller but it all worked out). The 2000 is only available with metric threads but that wasn't too bad as the original mounted with screws so I just had to switch to metric. It probably took me an hour to switch the 3 over.

So, time to bench test. I had pulled the yoke and connected it but left the HV unhooked for now. I had a meter connected for cathode current. I flipped the switch. Current came up fine and rested in a good place. There were no unusual noises; I figured, well, that didn't fix it because I expected some sort of drama. I grabbed the HV probe. 24kv!

So, I did a quick re-install of the yoke & lugged the chassis over to the cabinet. Gentlemen, another one joins the living!

Yes, the yoke is crooked. I don't even have the convergence magnet assembly on the neck. I still have a half dozen caps to change in a "non-critical" circuits along with the reactance coil that I damaged earlier. Soon, though, I'll be able to start fine-tuning things. I'm very much looking forward to it!

I'd like to know the tricks to finding those new door knobs. I've got a TM-21 with a dead shorted doorknob, and I suspect the somewhat unstable regulated HV level and slightly higher (than I like) H out current/temp in my 21CT55 may have something to do with bad doorknob caps.

CONGRATS! Great to see this set coming back to life. :thmbsp:

I'd like to know the tricks to finding those new door knobs. I've got a TM-21 with a dead shorted doorknob, and I suspect the somewhat unstable regulated HV level and slightly higher (than I like) H out current/temp in my 21CT55 may have something to do with bad doorknob caps.

I typed MuRata 1000pf 20kv, 2000pf 40kv into Mousers search and they came right up. Unfortunately many of them are now listed as End of Life: Scheduled for obsolescence and will be discontinued by the manufacturer.

https://www.mouser.com/ProductDetail/Murata-Electronics/DHS4E4G202KT2B?qs=%2fha2pyFadugtghO2xjgkP1MZe9dFhf kLzDjDjtFtIoF37yTXEZqe9w%3d%3d

I'd like to know the tricks to finding those new door knobs. I've got a TM-21 with a dead shorted doorknob, and I suspect the somewhat unstable regulated HV level and slightly higher (than I like) H out current/temp in my 21CT55 may have something to do with bad doorknob caps.

Let me know what you're looking for and I'll see what I can find.

I replaced the reactance coil tonight. I had 3 or 4 NOS Miller or Meissner replacements but I couldn't figure out how they were supposed to work as the original had 5 terminals and these have 6. They all have one terminal painted with a green dot but the Philco had it on the opposite side. Well, I solved my problem because further digging in my box-o-coils turned up a genuine Philco "pull". It has a different suffix but my cross reference charts take it to the same replacement. I got that installed after supper and, since I could now get audio on the bench with a converter box connected, naturally I had to try it again with everything hooked up. This is when it gets to be fun! Plenty of work to do but I'm very happy with how this is turning out.

Looking very promising. :thmbsp:

:yes:Already past HV repairs, video and locking in on color info, you got lucky with that part. You can see the right color differences in that screenshot on Les' Nessman's forearm, all despite the purity issue.
Keep the great progress rolling!

Let me know what you're looking for and I'll see what I can find.

I'm looking for the following. 2500pF @ 30KV, 1200pF @ 15KV, and 1000pF @ 10KV. I'm probably going to get a 2000pF 40KV for the first one since I feel 30KV is under rated for a 25KV line that can do over 30 if the regulation fails, and Bob G has had success with that value...I think I can find the 1000 on mouser, but I'm not sure what to do about the 1200...it seems Murata does not make that value of door knob anymore according to the datasheet for that part family. If I can I'd like to go up 5-10KV on all the door knobs I order to ensure they last as long as I live (especially since they are getting discontinued). Also according to the datasheet the threaded ends only project about 1mm so I'm going to have to come up with something with the parts available at the local hardware store to match the 1" terminal projection of the originals.

If you rather we discuss this privately send me an email. My PM box is full.

Tom, I'll try to email you soon.

I did have a setback. I finished replacing the last of the caps (all in the color circuit) and tied up some other little loose ends. The set powered up great. I was adjusting the HV to specs and it was very, very close. Then, without warning, HV went away. I was able to bring it back to some extent with an external horiz osc source but as of right now I have good voltages at the horiz. output, no red plating, no HV. Another clue: the Philco information (found at the ETF website-thanks Nick!) has you connect a meter in place of the sweep circuit fuse. It's supposed to read 2.1ma but I was getting 160ma. (Though now, on the bench, it's back to normal) I also noted excessive heat at the horizontal limiting coil. Even before this, I kept coming back to things not being right in the -25v line. So, I have it back on the bench and am slowly trying to troubleshoot. Oh, well, I went through a similar struggle with my CTC-5 many moons ago and it worked out in the end. I am anxious to get this behind me so I can start waking up the color circuit.

I've been chasing this thing in circles for weeks now. Time to call in the calvary! Maybe some of you, who unlike me know what you're doing, can point me in the right direction? Part of the Photofact schematic is posted. To recap:

I had 26kv & a nice raster. As I was adjusting the HV I suddenly watched it fall while the HO tube cathode current jumped & the picture started to fade. I shut it down.

Where I'm at currently: HV is around 12kv with a dim raster, pulled in on the left about 1/4 of the screen. It takes perhaps 45 seconds for the HV to come up. Cathode current is on the high side. The horizontal limiter coil is getting very hot, and in short order; I put a meter on both sides of it and each is seeing over 200ma. After running a few minutes the core of the flyback is hot. There are no outward signs of distress to the flyback (no dripping wax, no cracks, no arcing). All resistance readings on the fly are correct.

The set has been recapped including the doorknobs. I didn't change C164-167 but did a quick & dirty sub with the closest thing I had on hand & nothing changed. I tried a temporary swap to a later RCA 21" yoke with no change. All tubes in the circuit have been swapped more than once with NOS. Disconnecting the HV regulator had no effect. I tried adding R268 & C239 which Philco added to later runs-no change. External sources for horiz drive made no change. Chassis voltages, last I checked, were good.

Anything I'm missing? I know the problem is right in front of me; I just can't see it.

Could your damper have shorted? Also have you tried unhooking the doorknobs?.... I know they are new, but you can't rule out infant mortality.

If I'm understanding you correctly, you recapped the doorknobs?

I've never seen one fail, but to each their own I guess.

One of your diode couplers likely isn't working, or the filament windings have shorted to ground. Did you restring them yet? I always do, wiring doesn't last forever...

If that's not it, I bet one of your new doorknobs went bad. Measure the voltage at each point in the doubler circuit, you'll probably find a loss somewhere.

I have a bunch of doorknobs ere if you need.

1) The doorknobs. I had an early b/w set with a bad doorknob once; easy enough to repair. I have an assortment of "pulls". From what was on the webpage that Dave had for his TV123, he had to replace them due to a rectifier that was red-plating. I had a no-HV condition earlier in the resurrection process that was cured by changing them...I'm not sure which was bad. The 3 higher value caps were replaced with new production Murata units ($$$) while the one in the focus circuit is the same rating typically seen in early b/w stuff so I swapped in another I had on hand. Tonight I disconnected or swapped around the replacements with no change. While I was at it I also replaced the 4.7 ohm resistor in the base of the diode coupler.

2) I never thought about restringing the filament windings. I can't see anything obvious but its hard to tell what might be hidden where it wraps around. I have plenty of replacement HV wire so maybe I'll give it a try. This raises a question: is there any polarity that has to be observed? (I don't see how it could matter)

3) The damper-Nick included a NOS tube when I got it, plus I bought a spare. Swapping brought no change.

I need to reexamine the stack of 68mmf/5kv caps in the width coil/yoke circuit. I previously loosened one end and subbed something halfway close to see what would happen but nothing changed. Now that I have the HV cage all torn apart, my access is as good as it will ever be. I should just order some and be done, whether they're good or bad. I'm not sure how failure prone they are-I guess they're ceramic.

No polarity, it's heaters.

The wiring doesn't typically go 'bad' per se, but rather begins to leak HV the older it gets. Thus you won't typically have a direct short in the filament windings (which usually results in an audible hiss and the smell of ozone), but you will sometimes have quite a lot of leakage which tends to drag down the power supply wholesale. Remember that any current lost in the HV circuit is also current which is unavailable to drive the CRT, which is one reason I pay so much attention to the horizontal section. The other being unobtanium flybacks.

This problem is exacerbated by the attractive properties of HV, leading to the accumulation of potentially conductive dust and in turn more leakage. The cure for this is of course cleaning, but if you're gonna go that far you may as well just restring it anyway. I keep a spool of Belden 40kv stuff around for precisely this purpose. Don't forget to look for tin whiskers on the HV tube sockets either, those took my Hoffman out of service for a little bit and the length of them can be really surprising. If you see any, clean with fine grit sandpaper. A rag will just move them around, and they really need to be broken up to be rid of them. Protect bare metal from corrosion with WD-40, or other light water displacing oil. Do not paint!

Your problem happened all of the sudden though, which makes me think a doorknob failed on you.

Let's get systematic about this: Set the chassis up so that you can read horizontal cathode current, and take a reading with the whole circuit in play. Next see what happens if you pull V24 and V25, if cathode current is in a more or less normal range and you have good focus voltage, reinstall V24 and see what happens. Isolate the problem by process of elimination. You should expect to see a slight bump in cathode current with each tube that is reinstalled because of the heater, but if it jumps significantly it may point to a problem.

Don't forget to rule out the CRT either, if it suddenly went gassy it would cause these problems. I hope not, but something to look for. Your shunt tube grid circuit is another area to investigate, the 6BK4 will drag HV down real fast if something went wonky with it. Could be tin whiskers in the HV pot as well, just gotta get to eleiminating each part in turn.

Tonight I checked cathode current with V24/V25 out of circuit & saw no significant change. I disconnected the 68mmf caps previously mentioned and saw a noticeable boost in hv, maybe 1-2kv. Pulling the cap off the 6BK4 didn'[t change the HV. Next I'm going to sub another pot for the HV reg control. In-circuit it measured fine but I know that can lie. 2 things are pointing me in that direction: under some circumstances I can adjust the HV with it to a certain point but after roughly the halfway point there is no further increase. Then there was the fact that I was adjusting that pot when things went south. There are no signs of trouble from the pot by looking at it.

One thing i know-that horiz limiting coil is really putting off some heat! Anyway...excellent advice, miniman. Just the kind of stuff I'm looking for.

1) The doorknobs. I had an early b/w set with a bad doorknob onceYeah, not a high-failure item, but I ran across a bad doorknob cap while restoring my Dumont RA-102:

https://antiqueradio.org/DuMontRA-102CliftonTelevision.htm#doorknob

At first, the doorknob created subtle horizontal blips -- maybe leaking a little -- and then it failed dramatically.

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

Hot coil implies dissipation- power should not be dissipated in the linearity coil. Switch from reading HOT cathode current to reading total input power to the horizontal circuit- put your ammeter where the fuse normally is and see what you get. Power is going somewhere it’s not supposed to go, either you lost drive or something is shorted somewhere. Either way you have to track it down before you burn something out, I don’t think you’ll find a LIN coil for this thing if it goes bad...

Most of my hobby time has been used up over the last couple months with a home-improvement project. Now, back to the Philco!

1) The LIN coil: I studied it more carefully, peeling back the tape the factory wrapped around it. Ugh, it looked like crispy critters. Not open, but as bad as it looked it sure seemed to be shorting. I couldn't help myself...I decided to try rewinding it. My first attempt wasn't pretty but at least didn't make anything worse as I had the same HV...and the same overheating coil. After a few weeks I took the time to take it apart and do a better job, getting more much more precise with wire length and neatness. (No, not going to win any awards.) Result: no difference in set performance but the coil no longer heats up.

2) I replaced the filament windings for V23 & V25, nice and neat. No change. V24 was another thing, and at first I didn't think it was even possible (the leads disappeared deep into the center of the flyback). Well, last night after careful examination I determined that the winding was actually around the outside of the main donut, but plastered with tape and epoxy. I really wanted to leave it alone but found the the short bit of leads that were between the flyback and the socket were very brittle and cracked when I bent the wires. Okay: put my Dremel to work and VERY carefully cut away enough to pull the old wires out and run a new winding. I then coated the outer donut with some HV putty and hooked up the the leads. (My plan is to shellac the flyback later on). Powered it up tonight and...drats! No change!

3) Clue? I can see the filament lit in V23 & V25 but what partly pointed me to having to break down and change the other winding was seeing that there was no light in V24. Don't worry, I've tried swapping it several times & tested the tube filament, besides. I also clipped-in a 2.5v bulb and it lit just fine. I'm not smart enough to understand why else the filament wouldn't glow. (yes, I know it would be very faint). I've swapped the resistor in the filament.

A few other things: I've tried swapping the doorknob at V24. I even tried swapping in an old stick rectifier. Nothing I do can get the HV above 12kv. Note that my testing is with the yoke connected but not the crt. I also notice that the flyback core is getting too high. Something is putting too much load on it...what? I'll keep plugging away. If anybody sees something I should try, let me know.

After all of that, V-24 is still not lighting?. Perhaps broken connector on the tube socket? :scratch2:

jr

After all of that, V-24 is still not lighting?. Perhaps broken connector on the tube socket? :scratch2:

jr

Another possibility is the socket has an internal short across the heater... the load from that could sag the HV.

I'm looking for the following. 2500pF @ 30KV, 1200pF @ 15KV, and 1000pF @ 10KV. I'm probably going to get a 2000pF 40KV for the first one since I feel 30KV is under rated for a 25KV line that can do over 30 if the regulation fails, and Bob G has had success with that value...I think I can find the 1000 on mouser, but I'm not sure what to do about the 1200...it seems Murata does not make that value of door knob anymore according to the datasheet for that part family. If I can I'd like to go up 5-10KV on all the door knobs I order to ensure they last as long as I live (especially since they are getting discontinued). Also according to the datasheet the threaded ends only project about 1mm so I'm going to have to come up with something with the parts available at the local hardware store to match the 1" terminal projection of the originals.

If you rather we discuss this privately send me an email. My PM box is full.

I have tons of nos Rca and Zenith tv parts, I'll take a look and see if I have anything like that

I've studied that socket very carefully; although I can't see anything out of place (and no corona/etc in the dark) I may just try subbing it. I should mention, there is a 4.7 ohm resistor in series with the filament and I've swapped it not once but twice.

The other day when I tested with a bulb I had all leads unhooked from that socket and just hooked up the bulb alone (it lit, with a little bit of "gassy" glow visible). Tonight I stuck the leads of the light in the socket (with tube removed) and it glowed purplish as HV came up, then went dark. Its filament never lit. What does it mean? As Pee Wee Herman once said, "I don't know!"

I have tons of nos Rca and Zenith tv parts, I'll take a look and see if I have anything like that
A good ways back I bought door knobs for my CT100 21ct55 TM21 and CTC4.... think it cost me like 400 simolians. I'm pretty much set now.





I've studied that socket very carefully; although I can't see anything out of place (and no corona/etc in the dark) I may just try subbing it. I should mention, there is a 4.7 ohm resistor in series with the filament and I've swapped it not once but twice.

The other day when I tested with a bulb I had all leads unhooked from that socket and just hooked up the bulb alone (it lit, with a little bit of "gassy" glow visible). Tonight I stuck the leads of the light in the socket (with tube removed) and it glowed purplish as HV came up, then went dark. Its filament never lit. What does it mean? As Pee Wee Herman once said, "I don't know!"

If it is not lighting in socket that points to socket problems.