Another local Hoffman! COLOR!

[Yamamaya42]

Found a Hoffman colorcaster television local.

don't have it yet

http://suzaku.live-evil.org/hoff112.jpg
1967 w a 23EGP22 CRT

[Yamamaya42]

looks at the SAMS folder...

This thing is an RCA clone!

[AlanInSitges]

...with a Zenith picture tube!

[Yamamaya42]

Originally Posted by AlanInSitges

...with a Zenith picture tube!

Yes, it does look like a Zenith type cataract, but the sticker on the back says sylvania, did they use the Zenith method?

http://suzaku.live-evil.org/zenuth.jpg

[reeferman]

Zenith didn't make a 23EGP.

BTW, what's the "Zenith method"?

[Yamamaya42]

Originally Posted by reeferman

Zenith didn't make a 23EGP.

BTW, what's the "Zenith method"?

From what I have seen here and there, there are only 2 major types of methods (styles) of bonded safety glass used in these things, RCA, which turns white & cloudy (moldy) looking, best removed with heat, and the Zenith type of bond, which turns green and gummy, best removed with thin wire, and a lot of patience and strong hands!

As E.M. Has confirmed, this tube does indeed have the Zenith type of bonding used for the safety glass, meaning it will be much harder, and not to mention hazardous than the RCA 21FJP22 ones I have done before.
As I have heard that these tend to be more unstable in the process than the roundies,

[Electronic M]

Originally Posted by Yamamaya42

From what I have seen here and there, there are only 2 major types of methods (styles) of bonded safety glass used in these things, RCA, which turns white & cloudy (moldy) looking, best removed with heat, and the Zenith type of bond, which turns green and gummy, best removed with thin wire, and a lot of patience and strong hands!

As E.M. Has confirmed, this tube does indeed have the Zenith type of bonding used for the safety glass, meaning it will be much harder, and not to mention hazardous than the RCA 21FJP22 ones I have done before.
As I have heard that these tend to be more unstable in the process than the roundies,

I'd call it mid-level danger. The 23EGPs with RCA style cataracts tend to implode when heated worse than round or later rectangular tubes. The Zenith guitar string method has has a 100% success rate for me on the yellow/green cataracts, and doesn't use heat.

If you remove the cataract with heat it'll probably implode. If you remove it with just guitar string it'll probably be fine, but a raw 23EGP has a slightly higher implosion risk just sitting there than other color tubes.

[Electronic M]

Sylvania CRTs do get Zenith style cataracts, and supposedly respond to the same removal methods. The only Sylvania color CRT I've had was a post safety glass tension banded tube so I've never verified what I have read that they respond the same.

[DavGoodlin]

I have an RCA-style (moldy white crap) cataract on a 23EGP22 in an Admiral combo.

Tom: it sounds like no heat is safest, maybe even baking it in sunlight is a risk. The guitar string may need to be heated ala current source?

[Yamamaya42]

I have been looking at the SAMS for a while now, and just LOLing!
It's obviously an RCA CTC-17 -ish type clone, with mods, but what got me was the totally pointless mod of what is called the “color caster” color indicator circuit, which is 2 NPN transistors hooked to the color bandpass, which turns on 3 lights when color is present.... WHY BOTHER? :O


HEY, WE HAVE COLOR! let's light up the color, and tint controls!

[old_tv_nut]

Originally Posted by Yamamaya42

I have been looking at the SAMS for a while now, and just LOLing!
It's obviously an RCA CTC-17 -ish type clone, with mods, but what got me was the totally pointless mod of what is called the “color caster” color indicator circuit, which is 2 NPN transistors hooked to the color bandpass, which turns on 3 lights when color is present.... WHY BOTHER? :O


HEY, WE HAVE COLOR! let's light up the color, and tint controls!

Well, hypothetically, the color could be turned all the way down accidentally by kids or even the supposedly intelligent owner.

Of course, in later years we had cable systems that never turned the color burst off on anything including black and white movies, producing crosscolor when it should have been killed. By then no sets had a color indicator, but it would have been useful to me after I turned the color down deliberately on black and white movies.

Edit: well, not really useful, as it would always indicate color, but it might remind me to turn the color up again.

[Yamamaya42]

1 is good, 2 is a charm, 3 is nuts! :P

http://suzaku.live-evil.org/crazy-color.jpg

[Yamamaya42]

Originally Posted by Yamamaya42

1 is good, 2 is a charm, 3 is nuts! :P

http://suzaku.live-evil.org/crazy-color.jpg

Seems that all 3 of these gimmick lights are burned out. :O

Bad design.

NPN switch from the 6.3 fil power through a 1/2 wave rect, lighting up 3 2 volt bulbs through a 6.8 ohm resistor, as long as ALL 3 lamps are OK, all is fine, but if one burns out, then they ALL go because the voltage spikes.

they sell them in packs of 10, not gonna do it, I can get ultra bright yellow LEDs that run at 2-3 volts in packs of 20 cheaper.

[old_tv_nut]

Wow - they even had a color defeat switch. This would make the indicators useful as the user might have turned the color off with the defeat switch.

The reason for a color defeat switch was for cases where a set was used in a fringe area and the noise might have made the color killer unreliable. The color killer control could be set to make sure color programs got through, but the switch could be used to eliminate color snow on black and white programs without disturbing the color control setting. Obviously the color killer and color indicator could have different thresholds. I wonder if the color indicator tended towards false positives or false negatives under noisy conditions.

[Electronic M]

I always thought the color defeat switches on the various brands were to eliminate color on fringe color programs where the picture looked worse in color with snow than without color.