View Full Version : Mercury TV-220A restoration


bandersen
01-09-2016, 01:52 PM
A few weeks ago I was contact by forum member 'mrfixx' asking if I could get his old TV running. He said it was a Mercury TV which really got my head scratching.
Never heard of that brand before :scratch2: He provided a few pics and I started searching for any info. Maybe he'll chime in with the back story on how he came to own it.

https://farm2.staticflickr.com/1502/24264959995_54f8b9330c_o.jpg (https://flic.kr/p/CYdgee)

https://farm2.staticflickr.com/1617/24156799572_ded0a5606a_o.jpg (https://flic.kr/p/CNDUUm)

https://farm2.staticflickr.com/1521/24182409381_c1151cdcd6_o.jpg (https://flic.kr/p/CQVaNM)

Well long story short, I had business up his way yesterday, and stopped by to check it out. Other than some scratches on top, it's in pretty darn good condition. There's a pull out phonograph below (78 rpm?) and it's got a 16" 16RP4 CRT. So I'm guessing around 1951 vintage.

Pulled all the knobs, undid the chassis bolts and pulled the chassis. I don't think this set was ever serviced.
Every screw and bolt for the back and chassis was present and don't see any evidence of replaced parts.

Here it is back at my place.
https://farm2.staticflickr.com/1671/24194278691_7b2f4499d5_b.jpg (https://flic.kr/p/CRY194)

https://farm2.staticflickr.com/1679/24250673076_1dbc24f5c7_b.jpg (https://flic.kr/p/CWX3e3)

https://farm2.staticflickr.com/1495/24194279821_07c313da31_b.jpg (https://flic.kr/p/CRY1tx)

https://farm2.staticflickr.com/1699/23636727494_1f54a99e35_b.jpg (https://flic.kr/p/C1GpAo)

bandersen
01-09-2016, 02:03 PM
That tuner struck me as odd right away. Eventually, I found some service info in Riders vol 6 and 8.
It looks like Mercury was only around a very short while and only made sets with this basic chassis which is also listed under S.M.A. I don;t know who S.M.A is, but I'm guessing they made it for Mercury.

Vol 6 contains several pages of theory, alignment info and several schematics none of which quite match. Vol 8 has a one page schematic that seems to match very well.
Here's a link: https://drive.google.com/file/d/0B37VOP1BSxbAN090dnJRclZwd3c/view?usp=sharing
Couldn't find anything from Sams.

Now I can see that the tuner is a continuous type using 6 variable inductors. It covers the VHF low, high and FM bands. Supposedly, it also cuts juice to the horizontal circuit while in the FM band. I'm curious to see that in operation :yes:
It seems to be frozen right now. Hopefully, some carefully cleaning and lubrication will take care of that.
https://farm2.staticflickr.com/1501/24264959875_647e4551be_b.jpg (https://flic.kr/p/CYdgca)

I did all I could with the 16RP4 CRT, but can barely coax any emissions out of it. Luckily, I have a spare 16KP4 aluminized version that should fit perfectly.

Because it's so pristine I figure I'll restuff all the caps. I have a few outstanding projects to wrap up, then hope to dive right into it :thmbsp:

Meanwhile, any info on Mercury or S.M.A. would be much appreciated.

Electronic M
01-09-2016, 02:25 PM
Mercury was a record label, and judging by the decal it is probably the same Mercury.

TV was big into the mid 50's, and when that set was made two other record companies (RCA Victor, and CBS Columbia) were making phonos and TVs so they probably got in to TV as a sort of "me too" imitation of the big conglomerates.

mrfixx
01-09-2016, 02:55 PM
I aquired this set from a friend of the family. My sister was going through their storage locker, saw this, and sent me a pic. I wanted it! So she delivered it here, and since I am VERY disabled, I asked for help getting it running again. While taking pictures the tv almost fell on me. As luck would have it, my wife was there to help get it off me. Cant wait to see it in operation... Fixx

David Roper
01-09-2016, 03:24 PM
Is the turntable missing? My guess would be most likely a 900 series V-M, though Webster Chicago is also a good possibility. Either way, in 1951 they almost definitely put a three-speed changer in it. A TV combo is only likely to have a 78-only changer if it also has channel 1.

jr_tech
01-09-2016, 03:24 PM
Mercury was a record label, and judging by the decal it is probably the same Mercury.

TV was big into the mid 50's, and when that set was made two other record companies (RCA Victor, and CBS Columbia) were making phonos and TVs so they probably got in to TV as a sort of "me too" imitation of the big conglomerates.

Good eye! that winged head logo is a match!
https://en.m.wikipedia.org/wiki/Mercury_records

jr

mstaton
01-09-2016, 03:57 PM
I bought a Mercury TV here in Idaho. Mine is newer(21") Maybe 1953? I believe they're made in Los Angeles

jr_tech
01-09-2016, 04:03 PM
I bought a Mercury TV here in Idaho. Mine is newer(21") Maybe 1953? I believe they're made in Los Angeles

Was that perhaps Pacific Mercury?
https://en.m.wikipedia.org/wiki/Pacific_Mercury

jr

mstaton
01-09-2016, 04:17 PM
possibly. I have not looked in a long time

bandersen
01-09-2016, 04:44 PM
Is the turntable missing? My guess would be most likely a 900 series V-M, though Webster Chicago is also a good possibility. Either way, in 1951 they almost definitely put a three-speed changer in it. A TV combo is only likely to have a 78-only changer if it also has channel 1.

The turntable is there. I recall it was very basic but there might have been a speed selector.

jr_tech
01-09-2016, 05:48 PM
Interesting set of brochures linking to Mercury records in Chicago, not Pacific Mercury in Van Nuys.

http://www.ebay.com/itm/MERCURY-RADIO-TELEVISION-RECORD-PERFORMANCE-WITH-ORIGINAL-ENVELOPE-1950S-/371524348920?hash=item568093abf8:g:OPMAAOxycD9TWv5 P

jr

Adam
01-09-2016, 06:04 PM
I used to have a 12" round tube Mercury set. It used the same chassis as a Silvertone.

decojoe67
01-09-2016, 07:50 PM
I've been researching early TV for decades and never even heard of a Mercury TV. Very interesting. One thing for sure, in the early postwar years everyone and anyone attempted to jump on the band-wagon and market a television set. A friend of mine gets a constant flow of vintage sets and I've seen the most unusual names on them through the years. If you made a complete list of them all it would be huge.

bandersen
01-09-2016, 08:47 PM
Interesting set of brochures linking to Mercury records in Chicago, not Pacific Mercury in Van Nuys.

http://www.ebay.com/itm/MERCURY-RADIO-TELEVISION-RECORD-PERFORMANCE-WITH-ORIGINAL-ENVELOPE-1950S-/371524348920?hash=item568093abf8:g:OPMAAOxycD9TWv5 P

jr

Very cool! Too bad I don't see this set pictured. Odd that they had so many models and so little info exists about them.

old_coot88
01-09-2016, 09:03 PM
That canvas strap holding the jug on might be deteriorated enough to break easily. This has been the case with some split-chassis Philcos with canvas straps securing the CRT.

jr_tech
01-09-2016, 11:32 PM
That tuner struck me as odd right away. Eventually, I found some service info in Riders vol 6 and 8.
It looks like Mercury was only around a very short while and only made sets with this basic chassis which is also listed under S.M.A. I don;t know who S.M.A is, but I'm guessing they made it for Mercury.

.....snip....

Meanwhile, any info on Mercury or S.M.A. would be much appreciated.
Oddly the same eBay vendor that listed the Mercury TV brochures also has some trade show pictures featuring S.M.A. , Chicago:

http://www.ebay.com/itm/TELEVISION-PICTURES-S-M-A-CO-CHICAGO-AT-A-TRADE-SHOW-7-items-/311504819041?hash=item4887225361:g:ZMMAAOxyThVTX-ny

jr

Eric H
01-09-2016, 11:46 PM
There's another thread here about Mercury sets, seems Brando is seen with one in Streetcar, or maybe it's On the Waterfront? it's different model however.

http://videokarma.org/showthread.php?t=253029&highlight=brando

http://videokarma.org/attachment.php?attachmentid=172720&d=1325413209

bandersen
01-09-2016, 11:56 PM
That canvas strap holding the jug on might be deteriorated enough to break easily. This has been the case with some split-chassis Philcos with canvas straps securing the CRT.

Not to worry - there's a steel band underneath the cloth.

Oddly the same eBay vendor that listed the Mercury TV brochures also has some trade show pictures featuring S.M.A. , Chicago:

http://www.ebay.com/itm/TELEVISION-PICTURES-S-M-A-CO-CHICAGO-AT-A-TRADE-SHOW-7-items-/311504819041?hash=item4887225361:g:ZMMAAOxyThVTX-ny

jr

I think I see this tuner down at the bottom.

Polaraligned
01-10-2016, 08:44 AM
Because it's so pristine I figure I'll restuff all the caps.


That is impressive. Most guys just give their chassis "yellow" disease, unless it is a particularly rare and valuable set.

KentTeffeteller
01-19-2016, 07:29 PM
It is the same Mercury as the record company, they began by manufacturing radios, televisions, and phonographs, and in 1947 founded Mercury Records. And were purchased in 1961 by Philips of Holland. A beautiful early postwar set, and a very scarce set.

bandersen
01-19-2016, 10:56 PM
I got the set up on the workbench today. Looks like serial # is X4136. I wonder how many were made ?
https://farm2.staticflickr.com/1547/24197727620_c158818f9d_z.jpg (https://flic.kr/p/CSgFom)

Super clean inside the HV cage. Interesting focus and centering magnet assembly. It is both a permanent and electromagnet.
https://farm2.staticflickr.com/1475/23865307084_7a5351a7c4_z.jpg (https://flic.kr/p/CmTWkN)

I pulled the 5U4 rectifier and tried a power up. I quickly discovered a blown fuse and replaced it.
https://farm2.staticflickr.com/1605/23865096034_5b4af6a539_z.jpg (https://flic.kr/p/CmSRB1)

Success! Unloaded HV secondary is around 750 VAC.
https://farm2.staticflickr.com/1565/24493275655_8e89f90134_z.jpg (https://flic.kr/p/Djorw8)

Encouraged, I decided to give it a brief try with the rectifier in while carefully monitoring the B+. Things looked good but after a coule power cycles, the 5U4 died. I then worked on the frozen tuner a while and was able to free it up. I popped in a new 5U4 and gave it another go. It held up and I was able to pick up some FM stations :)

I also removed the weak CRT and installed a 8XP4 bench CRT. I have to keep it at an awkward angle because the grounding strap makes contact with the HV button.
No luck - 0 HV. Still not bad for a first power up. I'll get to recapping next.

https://farm2.staticflickr.com/1506/24410884491_2b506a99fc_z.jpg (https://flic.kr/p/Dc7auP)

https://farm2.staticflickr.com/1693/24410885421_bf247ff9f0_z.jpg (https://flic.kr/p/Dc7aLR)

dtvmcdonald
01-20-2016, 11:24 AM
Mercury Records produced the finest sounding recordings ever made, in
many people's opinions. The main reason was the exact polar pattern
vs. frequency curve of the microphones they used ... plus the extremely
low noise and high dynamic range (up to 140 dB!) of the tube used as
the microphone cathode follower. Google "Wilma Cozart".

bandersen
01-21-2016, 02:34 PM
I replaced the four corroded sand coated power resistors and recapped the horizontal circuits. I gave up on restuffing after the first two cardboard cap tubes crumbled.

There is a funky assortment of resistors like I've seen in other early 50s sets. Perhaps due to Korean war shortages plus the huge demand for TVs.
Also seeing some deviation from the schematic like this 39 ohm plus two 1M in parallel. The schematic shows a 47 ohm and single 1M. I figure it's best to stick with the values I find in the set.
https://farm2.staticflickr.com/1495/24416147312_0d7276df11_z.jpg (https://flic.kr/p/Dcz8X7)

Did another power up and started hearing some arcing in the HV area. Some investigation revealed a splice in the HV lead and a dirty HV rectifier socket.

https://farm2.staticflickr.com/1642/24416146112_7ce7407469_z.jpg (https://flic.kr/p/Dcz8Aq)

https://farm2.staticflickr.com/1582/24498244296_96b4606e08_z.jpg (https://flic.kr/p/DjPUwm)

Eventually, I also discovered the 1B3 had a crack in it. Not sure if it was always there or if the arcing caused it.
https://farm2.staticflickr.com/1548/24228877760_e81c25f9c1_z.jpg (https://flic.kr/p/CV2keJ)

With that sorted out, I finally got raster :)
https://farm2.staticflickr.com/1684/24498256446_bb4f667604_z.jpg (https://flic.kr/p/DjPY8Q)

Swapped out a bunch of weak or shorted tubes and got better sound and contrast. Think I'll focus on the vertical circuits next.
https://farm2.staticflickr.com/1528/23896254264_34dd379259_z.jpg (https://flic.kr/p/CpCxRS)

bandersen
01-26-2016, 11:02 AM
I replaced the electrolytic caps in the B+ supply and vertical output circuits. All four of the can electrolytics in this set have cardboard covers over them which I was able to remove with a little heat. Then, I cut them open and installed the new caps. Once I'm done, I'll pop the cardboard back on to hide them.
https://farm2.staticflickr.com/1718/24488293052_a9ab6c73dd_z.jpg (https://flic.kr/p/DiWUnb)

Now I've got full height and good linearity. I also installed a new, longer HV lead so I can flip the test CRT around and avoid that grounding strap.
https://farm2.staticflickr.com/1579/24488293682_db6771f370_z.jpg (https://flic.kr/p/DiWUy3)

bandersen
01-26-2016, 04:01 PM
I finished recapping the set and popped the original CRT back in. Since it had tested so poorly I wasn't surprised that the best I could get was a dim, out of focus image. I had to dim the lighting to take this photo. The brightness control has virtually no effect.
https://farm2.staticflickr.com/1609/24005185834_b9171a21ae_z.jpg (https://flic.kr/p/CzfRqo)

Replacing it with a good 16RP4 made a very noticeable difference!
https://farm2.staticflickr.com/1582/24337785570_882077b475_z.jpg (https://flic.kr/p/D5DvJA)

Tweaking the controls improved the focus and brightness is most definitely much better. I do have some streaking though. I'll check the peaking coils and video amp circuit.
https://farm2.staticflickr.com/1607/24006541413_8eba48f63e_z.jpg (https://flic.kr/p/CznNor)

https://farm2.staticflickr.com/1650/24633329305_cbd450aff0_z.jpg (https://flic.kr/p/DwLfAe)

timmy
01-26-2016, 06:25 PM
That chassis looks similar to the RCA 630 set.

Radiotronman
01-26-2016, 06:54 PM
Starting to look pretty good!

timmy
01-26-2016, 08:28 PM
Amazing what new caps can do. :D

decojoe67
01-26-2016, 08:45 PM
Looks good! Nothing like seeing a set that was dormant for so many years come to life.

bandersen
01-26-2016, 08:46 PM
Here's a look inside the continuous tuner. They use a three position cam to skip the FM band and move it to the end so it goes 2-13 then FM. That also gives it a nice wide FM tuning range so it's not all bunched up.
Power to the flyback is also killed while in the FM band so the screen goes dark.
https://farm2.staticflickr.com/1679/24555266321_cd91670a6c_z.jpg (https://flic.kr/p/DpSabH) https://farm2.staticflickr.com/1461/24611509506_51681c36f1_z.jpg (https://flic.kr/p/DuQqjN)

bandersen
01-27-2016, 12:56 PM
I replaced a few more out of spec resistors, reinstalled the tuner and twiddled with the controls a bit more.
Picture is better, but still not quite happy. I'm getting sound at two points - very noticeable when tuning the FM band.

So I figure I'll go through the alignment procedure. It looks pretty standard with a 21.25 MHz sound and 25.75 MHz video IF.
https://farm2.staticflickr.com/1631/24615090026_4abec4384d_z.jpg (https://flic.kr/p/Dv9LFU)

I managed to install a NOS cord by heating it up and mushing the ears over the rivets.
I don't have many of this type cord left. They used to be so common - never figured the supply would dry up :(
https://farm2.staticflickr.com/1452/24568660381_00173043d6_z.jpg (https://flic.kr/p/Dr3NLM)

Also getting ready to recoat the CRT with some Slip Plate.
https://farm2.staticflickr.com/1488/24650851785_8a2735272d_z.jpg (https://flic.kr/p/Dyj4pX)

bandersen
01-28-2016, 12:26 PM
CRT turned out nicely - still working on the alignment...
https://farm2.staticflickr.com/1705/24646772666_9f85641ede_z.jpg (https://flic.kr/p/DxX9Qj)

Kamakiri
01-28-2016, 02:14 PM
What's this slip plate stuff? :)

Electronic M
01-28-2016, 02:30 PM
What's this slip plate stuff? :)

Basically aquadag spray paint. If dag is flaking off it is one of the presently made/available products to re-coat/replace old dag with.

Eric H
01-28-2016, 04:57 PM
I've been using this stuff to recoat, done three tubes with this can and it still feels nearly full.

Unlike Slip Plate. it makes a hard black coating that doesn't easily mar or rub off on your fingers.

It's quite conductive too, I measured the resistance from one side of a 14" tube to the other and it was about 2k.

You can get it on Amazon for about $16 if you have Amazon Prime.\

http://www.amazon.com/MG-Chemicals-Conductive-Coating-Aerosol/dp/B008OA931A/ref=sr_1_1?s=industrial&ie=UTF8&qid=1454021795&sr=1-1&keywords=total+ground+carbon+conductive+coating

Paul Knaack
01-28-2016, 05:50 PM
What sorts of symptoms would you notice if about 1/2 or 3/4 of of the dag coating were missing, even if all remaining dag were still grounded?

Electronic M
01-28-2016, 07:45 PM
Dark patches on the screen from poor HV filtering and or noise on screen....Also rarely does a significant portion of the dag come off without "islands" forming, and the islands tend to arc to each other/other dag and grounds which may cause implosion....So far (knock on wood) I can't say I've seen a set with more than %10 (the most I'll tolerate before wanting to recoat) bad or lost dag. If dag damage ain't bad I eradicate dag islands and move on with my life.

Paul Knaack
01-28-2016, 07:52 PM
Thanks Tom,

Polaraligned
01-28-2016, 08:23 PM
I love how the slip plate makes my CRT's look like new.
The stuff Eric linked to looks pretty nice also. Looks closer to factory.

Kevin Kuehn
01-28-2016, 09:52 PM
Also rarely does a significant portion of the dag come off without "islands" forming, and the islands tend to arc to each other/other dag and grounds which may cause implosion

Is this really a well documented phenomenon, the resulting in implosion part? Don't recall ever reading about that before. :scratch2:

Electronic M
01-29-2016, 12:14 AM
Is this really a well documented phenomenon, the resulting in implosion part? Don't recall ever reading about that before. :scratch2:

I've read about ground strap arcing causing implosion, Zenith safety cap arcing (HV button to yoke) causing implosion, and I've heard of the islands arcing to each other. I don't know of any cases of island arcing causing implosion, but it is possible....Arcing generated intense local heat, uneven heat of glass causes fracturing, fracturing of glass under vacuum causes implosion.
I rather not risk it.

Kevin Kuehn
01-29-2016, 10:35 AM
Agree it's best to error on the safe side. However my gut feeling is you'd be hard pressed to heat up an area of a CRT through conduction of it's dag coating, considering the typical resistance of the material and it's low thermal mass. Might be a fun youtube experiment. :)

Electronic M
01-30-2016, 12:34 AM
Agree it's best to error on the safe side. However my gut feeling is you'd be hard pressed to heat up an area of a CRT through conduction of it's dag coating, considering the typical resistance of the material and it's low thermal mass. Might be a fun youtube experiment. :)

It's not conductive heating of the dag at all. An arc essentially forms a super heated conductive plasma in the air to carry current. If you've ever experimented with high voltage arcs (like a Jacob's ladder or a plasma speaker or an automotive spark ignition system) you know that an arc generates enough heat to easily light paper, a cigarette, gasoline, and even burn/erode metal.

If you put your finger in the middle of a 20KV arc and you are not connected to either supply pole you will feel more pain from the plasma burn than the shock (as I know first hand).

bandersen
01-31-2016, 07:56 AM
I got the recoated CRT installed without any troubles :)
https://farm2.staticflickr.com/1444/24341679499_57a741ca33_z.jpg (https://flic.kr/p/D5Ztgi)

I believe this chassis was originally designed for round CRTs because of a couple clues.
One - This tube bumps into the CRT and there's no room to install a shield.
https://farm2.staticflickr.com/1594/24341680539_550c6d4e93_z.jpg (https://flic.kr/p/D5Ztze)

Two - The discriminator coil is mounted under the chassis. That gave me a headache while doing the alignment as the instructions for adjusting the top and bottom slugs are the opposite of what I needed to do.
Sound is excellent now :)
https://farm2.staticflickr.com/1501/24264959875_647e4551be_z.jpg (https://flic.kr/p/CYdgca)

I then fought with the ion trap magnet and centering rings to eliminate corner shadows and minimize distortion. Still not entirely happy, but it's not very noticeable while viewing programming.
https://farm2.staticflickr.com/1510/24709350625_43f925632e_z.jpg (https://flic.kr/p/DDtT5D)

So that's a wrap for the chassis restoration. Next up I'll arrange for a trip to reunite it with it's cabinet.
https://farm2.staticflickr.com/1544/24709349295_0901bb1688_z.jpg (https://flic.kr/p/DDtSFH)

decojoe67
01-31-2016, 09:21 AM
....So that's a wrap for the chassis restoration. Next up I'll arrange for a trip to reunite it with it's cabinet.
https://farm2.staticflickr.com/1544/24709349295_0901bb1688_z.jpg (https://flic.kr/p/DDtSFH)
Very nice Bob. You do superior work!

Radiotronman
01-31-2016, 09:27 AM
Another restoration that looks awesome! What's next on the restoration bench? Possibly a porthole or a remote set?

bandersen
01-31-2016, 11:06 AM
Nope. A Stromberg Carlson 21 inch tabletop I'm restoring for a client. I'll be starting a new thread soon.

Kevin Kuehn
01-31-2016, 03:44 PM
Excellent restoration, Bob. I'm surprised they didn't recess that tube socket 1/4" or so below the chassis.

bandersen
01-31-2016, 03:51 PM
Yeah that would have been a simple solution. Perhaps I could drill out the rivets and recess it :scratch2:

Kevin Kuehn
01-31-2016, 05:34 PM
If you put your finger in the middle of a 20KV arc and you are not connected to either supply pole you will feel more pain from the plasma burn than the shock (as I know first hand).

Tom, I'm sure you realize that with the Zenith color safety cap failures, it was because the high voltage would soar insainly high, at which point the HV could arc "through" the CRT neck glass to the yoke or convergence poles. But that's not the same thing that happens with sparks between adjacent dag islands or a grounding strap on the outside surface of a b&w CRT.

old_coot88
01-31-2016, 09:03 PM
...But that's not the same thing that happens with sparks between adjacent dag islands or a grounding strap on the outside surface of a b&w CRT.
Right. The arcky sparkies you'd get there would be more akin to rubbin' a cat's fur vigorously. But it will generate hash that'll sure play hobb with sync.

Electronic M
01-31-2016, 09:46 PM
Tom, I'm sure you realize that with the Zenith color safety cap failures, it was because the high voltage would soar insainly high, at which point the HV could arc "through" the CRT neck glass to the yoke or convergence poles. But that's not the same thing that happens with sparks between adjacent dag islands or a grounding strap on the outside surface of a b&w CRT.
I have a set with bad safety caps and it appears to arc over the surface of the glass, and not through it.

The other example I gave of a poor arcing ground strap connection was a surface arc too and that surface arc DID cause an implosion.

Jeffhs
06-23-2017, 09:47 PM
I noticed the aquadag coating on the CRT bell was flaking off (there is a large bare spot where the coating should be, even though most of the rest of the dag is still on the tube). I'd replace the tube, as it could be very weak--especially if the TV was made in the 1950s and was used a lot by its former owner(s). There could be high-voltage issues as well if the dag coating (or any part thereof) is missing, including arcing or even no raster. Because the dag is one part of a large HV capacitor in all CRT TVs, it is very important that the coating is intact over the entire surface of the tube bell.

Edit: I just looked at some other posts in this thread and found that Bob had recoated the CRT bell, thereby restoring the tube to normal, or at least as close to normal as one can come with a 1950s-era CRT. I was not aware (until just now) that flaking aquadag could be replaced, but I learned something tonight when I saw the references to Slip-Plate and the other compound mentioned.

BTW, the picture on the newly-recoated CRT looks good from here. Bob said there were still some issues with the image the tube produces, but from what I can see, the picture is pretty darn good. I would think defects in the raster, etc. would show up more prominently on a crosshatch pattern than on a standard program picture anyway.

dieseljeep
06-24-2017, 10:18 AM
I noticed the aquadag coating on the CRT bell was flaking off (there is a large bare spot where the coating should be, even though most of the rest of the dag is still on the tube). I'd replace the tube, as it could be very weak--especially if the TV was made in the 1950s and was used a lot by its former owner(s). There could be high-voltage issues as well if the dag coating (or any part thereof) is missing, including arcing or even no raster. Because the dag is one part of a large HV capacitor in all CRT TVs, it is very important that the coating is intact over the entire surface of the tube bell.

Edit: I just looked at some other posts in this thread and found that Bob had recoated the CRT bell, thereby restoring the tube to normal, or at least as close to normal as one can come with a 1950s-era CRT. I was not aware (until just now) that flaking aquadag could be replaced, but I learned something tonight when I saw the references to Slip-Plate and the other compound mentioned.

BTW, the picture on the newly-recoated CRT looks good from here. Bob said there were still some issues with the image the tube produces, but from what I can see, the picture is pretty darn good. I would think defects in the raster, etc. would show up more prominently on a crosshatch pattern than on a standard program picture anyway.
Entries #25&31 show a different CRT, than the original one. It was one Bob had that tested good, but the a-dag coating was flaking off.
I had read somewhere that Warwick aquired Pacific Mercury sometime in the 50's. They were building the Thomas organ there as well. :scratch2: