Yesterday I got a NOS Channel Master brand 25GP22 from Bob G.
I'm trying to install it in an Admiral that used a 25AP22....According to my sams CRT sub book they both cross to a 23VALP22 (yet neither is listed as a direct sub for the other) so I think electrically and bulb size wise it should work.
The new 25GP is a "speed fit" (all mounting hardware, degaussing coils, and shields come mounted to it) tube for Zenith sets, and the mounting ears that bolt it to the set are WRONG for the admiral (can't bolt it in).

I'm going to have to reuse all the mounting hardware from the previous CRT to make it mount, and that means I'm either going to have to cut the tension band (there is NO safety glass on this CRT) and remove the mounts it came with (which is 1 cut and guarantees a clean fit) or cut each ear off the mounts (8-12 cuts, and some hacking of the admiral's hardware).

What should I do?

Must be a built in safety screen. Dont remember ANY
rectangle color CRT without it. I wouldnt mess with the tension band
unless someone has done it. IIRC Admirals had big rubber
corners you had to cut for some swaps like the 23EG's BUT its
been over 40 yrs !!!! Zeniths had the ears as mounting &
the big fold-up DGS shield but I dont remember any big
rubber corners. Truth is its been to damn long & my memory
sucks..... May be you are hoping for a sub where there is none ?

73 Zeno:smoke:

Yesterday I got a NOS Channel Master brand 25GP22 from Bob G.
I'm trying to install it in an Admiral that used a 25AP22....According to my sams CRT sub book they both cross to a 23VALP22 (yet neither is listed as a direct sub for the other) so I think electrically and bulb size wise it should work.
The new 25GP is a "speed fit" (all mounting hardware, degaussing coils, and shields come mounted to it) tube for Zenith sets, and the mounting ears that bolt it to the set are WRONG for the admiral (can't bolt it in).

I'm going to have to reuse all the mounting hardware from the previous CRT to make it mount, and that means I'm either going to have to cut the tension band (there is NO safety glass on this CRT) and remove the mounts it came with (which is 1 cut and guarantees a clean fit) or cut each ear off the mounts (8-12 cuts, and some hacking of the admiral's hardware).

What should I do?
You don't ever want to mess with a tension band CRT.
More often than not, it'll implode in your puss. The tension band is cemented on with some form of epoxy resin.
Even cutting off the ear mounts, with the tension band, makes it rather hard to install in the original front bezel.
When altering anything on a tension band CRT, make sure to wear eye protection, or even better yet, a full face shield. :sigh:

A TV repairman friend cut the tension band on a 25V CRT and it wasn't long before it went BOOM! It's a miracle that he wasn't cut to pieces.

"should I cut the tension band or mounting hardware on a 25GP22?"

Do not cut the tension band !
The tension band provides implosion protection for the tube by placing the front panel of the tube in compression. Tension is likely on the order of 1000 to 1500 lbs. Without the tension band, you have a very unsafe condition, a tube that could implode easily. It is unlikely that you have the tools to re-band the tube after changing/removing the corner ears, so the tube will continue to be a hazard even when installed in the TV set.
Cutting off the ears is a less hazardous operation, but not risk free. Wear a "flack jacket" and full face mask, and be sure your neck is protected.

jr

You don't ever want to mess with a tension band CRT.
More often than not, it'll implode in your puss. The tension band is cemented on with some form of epoxy resin.
Even cutting off the ear mounts, with the tension band, makes it rather hard to install in the original front bezel.
When altering anything on a tension band CRT, make sure to wear eye protection, or even better yet, a full face shield. :sigh:

On this jug the Band is wrapped over the shield and mounts and there is no cement on it...Perhaps it is not a proper tension band?....At the least it is meant to hold the mounts on the CRT.

I'm probably going to hack saw/file the ears off the mounts, unless someone tells me that band is not bad to remove or comes up with a better idea.

There were many slightly different methods, some used epoxy under the rimband, others did not. Epoxy or not, the tension band is likely vital to the implosion protection system.
How about a picture of what you have?

jr

Here you go.
http://i1095.photobucket.com/albums/i469/ElectronicMemory/th_DSCN0576_zpsb9upgqxc.jpg (http://s1095.photobucket.com/user/ElectronicMemory/media/DSCN0576_zpsb9upgqxc.jpg.html)
http://i1095.photobucket.com/albums/i469/ElectronicMemory/th_DSCN0575_zpsxuxkprgy.jpg (http://s1095.photobucket.com/user/ElectronicMemory/media/DSCN0575_zpsxuxkprgy.jpg.html) http://i1095.photobucket.com/albums/i469/ElectronicMemory/th_DSCN0577_zpsbmi1e0mz.jpg (http://s1095.photobucket.com/user/ElectronicMemory/media/DSCN0577_zpsbmi1e0mz.jpg.html) http://i1095.photobucket.com/albums/i469/ElectronicMemory/th_DSCN0578_zpsp3fsrsp8.jpg (http://s1095.photobucket.com/user/ElectronicMemory/media/DSCN0578_zpsp3fsrsp8.jpg.html) http://i1095.photobucket.com/albums/i469/ElectronicMemory/th_DSCN0580_zpssuyyorhl.jpg (http://s1095.photobucket.com/user/ElectronicMemory/media/DSCN0580_zpssuyyorhl.jpg.html) http://i1095.photobucket.com/albums/i469/ElectronicMemory/th_DSCN0574_zpsp5hjaozp.jpg (http://s1095.photobucket.com/user/ElectronicMemory/media/DSCN0574_zpsp5hjaozp.jpg.html) http://i1095.photobucket.com/albums/i469/ElectronicMemory/th_DSCN0572_zps1nuqswsw.jpg (http://s1095.photobucket.com/user/ElectronicMemory/media/DSCN0572_zps1nuqswsw.jpg.html) http://i1095.photobucket.com/albums/i469/ElectronicMemory/th_DSCN0571_zpsmgmuihrx.jpg (http://s1095.photobucket.com/user/ElectronicMemory/media/DSCN0571_zpsmgmuihrx.jpg.html) http://i1095.photobucket.com/albums/i469/ElectronicMemory/th_DSCN0565_zpseweep8ei.jpg (http://s1095.photobucket.com/user/ElectronicMemory/media/DSCN0565_zpseweep8ei.jpg.html)

Ok! Then there appears to be no bonded safety glass... The tension band over the clam-shell is indeed the only means of safety protection. I would not remove the t-band! Even if you did, I suspect that you might find that the ears are spot-welded to the clam-shell and you would have to cut them off anyway, which would be very hazardous with the tension removed.

Jr

I'm leaving the band and sawing off the three mounting ears (per corner). The corner set's original corner brackets look to fit correctly that way from the test corner I did.

There are 8 push on rubber bumpers (as part of the admiral's factory mounts) that break the unsupported parts of the sides into thirds...They will be tighter with the band on, but I can make them just fit.

I ran into the same thing with a quik fit crt for a zenith. I think you did the right thing to no mess with the band. I ended up not using it but will save for a zenith that fit as is.

I ran into the same thing with a quik fit crt for a zenith. I think you did the right thing to no mess with the band. I ended up not using it but will save for a zenith that fit as is.

I honestly, never saw a CRT with all the mounting hardware installed. I knew they existed, but never considered it, because of the cost.
Most of my customers, that owned Zenith sets, requested a Zenith CRT, to be installed. I always considered, the regular type Zenith CRT's, to be the easiest CRT's to replace, the Motorola's, the worst. You had to fiddle with the mounting ears and the CRT went in from the front. :thumbsdn:
I guess C-M tried to win over more customers, with these schemes. I never liked the picture quality of even a brand new C-M. Most of the better line rebuilts, had a better picture. :scratch2:

I guess in a real high volume shop they make sense, but to me its really not that big of a deal to reuse the hardware.

The funny thing is even though its a zenith quick fit with all the hardware, it did not fit the zenith I wanted to use it in.

I have a Y zenith and the CRT was for an X, no joy. I ended up using a VDC standard replacement, still banded but no ears, The band made it somewhat of a difficult fit into the old magnetic shield (the crimp coupling would not fit inside the shield, I had to notch the shield for it). All that work and then I find the shadow mask had a defect resulting in a slight purity issue that I can't work out. I should have just left the old CRT, it was tired but at least no purity issues.

...

The correct answer is DO NOT REMOVE THE TENSION BAND WHILE UNDER VACUUM

I watched Scotty at Hawkeye do some rectangular tubes for bowling alley monitors. The band was removed only after the crt was at atmospheric pressure. After the tube was rebuilt and under vacuum, the final step was to replace the tension band using steel strapping like is used in strapping wooden crates. A special tool is used to apply the tension on the steel strapping and then another tool is used to place a clinch fastener to hold the bands tight. All done while tube is under vacuum. When I saw Scotty fasten the new band and tension it, I was afraid it would implode, but actually the tube is more likely to implode with the band removed.

I would use a high speed carborundum cut off wheel to saw the ears and remove them.

Bob

Bob, I have brought up this before but do not recall a definite answer.

Do you know if Scotty would band rectangle rebuilds that came in as bonded face?

I presume he would release the vacuum, put in oven to get hot, remove the bonded face, do the rebuild and add a band leaving the face lens off. But that is just what I think.

I don't know if he ever sold rebuilds that came in with bonded faces and then he would reattach with a bonding agent after rebuilt. Or maybe just sell back with no lens attached. I am talking about rectangles not roundies

One nice thing about those Motorolas is that you can remove a cataract without removing the CRT.
I never thought of that plus, but then, I never had to remove a cataract from a 23EGP22. They usually were bad! :D

The correct answer is DO NOT REMOVE THE TENSION BAND WHILE UNDER VACUUM

I watched Scotty at Hawkeye do some rectangular tubes for bowling alley monitors. The band was removed only after the crt was at atmospheric pressure. After the tube was rebuilt and under vacuum, the final step was to replace the tension band using steel strapping like is used in strapping wooden crates. A special tool is used to apply the tension on the steel strapping and then another tool is used to place a clinch fastener to hold the bands tight. All done while tube is under vacuum. When I saw Scotty fasten the new band and tension it, I was afraid it would implode, but actually the tube is more likely to implode with the band removed.

I would use a high speed carborundum cut off wheel to saw the ears and remove them.

Bob
They're available at Harbor Freight. The $9.95 4.5" angle grinder is good enough for the application.

I got it mounted late last night. I hack sawed off the tabs since I did not want to risk magnetizing it with a power tool....My back wishes I'd went with the power tool.

Purity is not quite right (though at least reasonably close)so I may remove the admiral's shield as two shields may be messing with purity.

Out of curiosity, what is printed on the red band clinch? I know I have seen them but can't recall, and your pic is out of focus.

And I agree - never cut a tension band.

"Signode" ??? just a WAG.

jr

"Signode" ??? just a WAG.

jr

Yes, correct.

We used to cut off ears all the time - mostly to fit 23V/25V tubes to older sets. Dad saved every CRT mount, every caster, every cabinet bracket, every foot and every trap door from sets he junked. His a$$ got saved quite a few times that way. I still have his box of treasures if anyone every needs any of the above. No complete sets, save for the CRT mounts - and the doors are mostly for mid-80s stuff.

Putting a 510NVB22 into a Barco CTVM 3/51 monitor. The ears were backward. Cut the band with tinsnips. To re-attach the band, I used a stainless steel hose clamp riveted to the band. The location of the hose clamp worm mechanism needs to be pre-determined as you may have mounting issues with the bezel and/or cabinet. I used two rivets on each side to fasten the hose clamp to the band. Also had to grind the ears down.
There really is no concern for implosion because if you've ever examined a crt disassembled, the glass is real thick at this location. In fact, the entire front glass is more like a lens than a piece of glass.

hmmm well I have been near one when it imploded, and sure I would not risk cutting a tension band. Note I have seem large hose clamp like bands that are really just mounting the jug, not for implosion protection. Tension bands are make from high tensile strength steel. I don't know what a hose clamp is made from, but I presume its not the same stuff.

hmmm well I have been near one when it imploded, and sure I would not risk cutting a tension band. Note I have seem large hose clamp like bands that are really just mounting the jug, not for implosion protection. Tension bands are make from high tensile strength steel. I don't know what a hose clamp is made from, but I presume its not the same stuff.
All the hose clamps I worked with were a good grade of stainless steel.
It seems like a lot of risky work, for a small reward.:thumbsdn:

...

There's no way you could get enough tension with a hose clamp to provide implosion protection. Unless it's going into something with a separate safety glass, I wouldn't risk it.

I've heard of CRTs that spontaneously imploded after the tension band was removed, but I don't know if it was true, or if there were other issues such as scratching the CRT with a hack saw while cutting the band. One of these days, I'll have to try it under controlled conditions on a dud.

It's a matter of statistics... You might do *one* with no implosion, but that really proves nothing... do 100 or so and it is fairly likely that you will experience an implosion when the band is cut off.

jr

"Signode" ??? just a WAG.

jr


:thmbsp: Signode is a large manufacturer of strapping equipment . They produce strapping machines for automated factory process using both steel and plastic strapping material .

Well I have decent purity and far better gray scale than before, but the new CRT is revealing that the chassis had some issues I'd in correctly blamed on the previous CRT.....The worst of which is that the monochrome video chain is not producing enough amplitude...To get bright enough white and reasonable contrast, the blacks need to be more lit than they should....The 6BN11 (video/sound-synch...synch was weak too) was half dead-half weak all I had in my stocks was a marginally good replacement and that helped a bit, but is likely not strong enough. HV is weaker than it should be (I remember it being fine before) and changing the reg settings to get the most out of it screws up the focus. There are some jali bars too that I'll have to address.

I'm going to set this aside for a few days and then regroup.

Is the set an H12 with a 6BK4 regulator and a 2AV2 focus rectifier?
The new CRT, with high emission, probably draws a lot more current. I worked on a few sets, where the CRT was so sick, you couldn't tell whether the set was properly or not. :scratch2:

Yes, H12.

I backed all CRT pots and jumpers down before first run of the new CRT, and adjusted from there....God, I hate that cockamamie CRT set up scheme they used: One screen pot, three grid drives, a wacky cathode jumper system, NO service switch, and a partridge in a pair tree~~.....It's like steering a car with your feet, and working brakes and gas with your hands!...If I was more ambitious I'd try to convert it to a system more like the RCA and Zenith setups I'm used to.....The hell was Admiral trying to do with that setup?....Be different for the sake of being different?