Looking for some picture tube help

[electroking]

As far as I know, replacing a tube with an ion trap by a tube without an ion trap just involves removing the trap.

Regarding your other question (pinout), I will let those that are more experienced comment about that.

Regards.

[kx250rider]

Originally Posted by electroking

As far as I know, replacing a tube with an ion trap by a tube without an ion trap just involves removing the trap.

Regarding your other question (pinout), I will let those that are more experienced comment about that.

Regards.

Correct on the ion trap. On the pinout, the only differences are whether the replacement tube is electrostatic focus or magnetic. Again, you can swap by making a couple changes. But most all TVs made after appx 1953 had static focus.

Charles

[mattdavala]

Originally Posted by kx250rider

Correct on the ion trap. On the pinout, the only differences are whether the replacement tube is electrostatic focus or magnetic. Again, you can swap by making a couple changes. But most all TVs made after appx 1953 had static focus.

Charles

I'm sure most TV's did have static focus although my 21 inch Majestic console has electrostatic focus and it is from 1955. Its CRT is a non standard replacement, 21EP4B. Its on its way out. ..... Brightness almost full, slight blooming, retrace lines on dark scenes.

If I never plan to sell my TV, spending 250 dollars for a CRT rebuild might be worth it. The TV is a joy to watch.

Best regards,
Matt Davala

[eberts]

The 21CXp4 is physically the same as a 21FLp4, but the G2 voltage uses about 50 volts instead of 300-450 volts. I tried it once using a resistor network to lower voltage, but the set had other problems, so into the trash it went.
21CBP4 would work.

I remember once some guy was going out of business, he had the whole second floor filled up with 100 brand new picture tubes from the early 50's still in their cartons. The cartons were so old if you touched them they fell apart. I know they were tearing the building down, he wanted big money for his so called inventory. Oh well.

It's sad to watch these old TV repairmen go senile.

[roundscreen]

Originally Posted by eberts

It's sad to watch these old TV repairmen go senile.

[electroking]

Hello,

Here is the table from the little book I mentioned a few days ago.
The tube types are (top to bottom) 21ACP4, 21ACP4A, 21AMP4,
21AMP4A, 21BSP4, 21CUP4. Regards.

[leadlike]

awesome! thanks for the list folks! Now I have an idea of what to look for....

cheers,

Wade

[electroking]

Originally Posted by mattdavala

I'm sure most TV's did have static focus although my 21 inch Majestic console has electrostatic focus and it is from 1955. Its CRT is a non standard replacement, 21EP4B. Its on its way out. ..... Brightness almost full, slight blooming, retrace lines on dark scenes.

If I never plan to sell my TV, spending 250 dollars for a CRT rebuild might be worth it. The TV is a joy to watch.

Best regards,
Matt Davala

What do you call 'static focus'? According to my RCA RC-29 Tube Manual
(1973), all B&W CRTs listed have either Electrostatic focus (a grid that
you connect to the correct potential, sometimes with taps, sometimes
with a potentiometer) or Magnetic focus (a focus coil). The only two
tubes that list a different focusing method (Automatic) are two test
tubes (8XP4 and 8YP4).

My two TVs, from 1956 and 1960, use electrostatic focus tubes
(21ALP4A, 90 deg. and 21DEP4, 110 deg.).

Regards.

[mattdavala]

Originally Posted by electroking

What do you call 'static focus'? According to my RCA RC-29 Tube Manual
(1973), all B&W CRTs listed have either Electrostatic focus (a grid that
you connect to the correct potential, sometimes with taps, sometimes
with a potentiometer) or Magnetic focus (a focus coil). The only two
tubes that list a different focusing method (Automatic) are two test
tubes (8XP4 and 8YP4).

My two TVs, from 1956 and 1960, use electrostatic focus tubes
(21ALP4A, 90 deg. and 21DEP4, 110 deg.).

Regards.

Here is where my lack of electrical knowledge is going to kick me in the butt. I thought electrostatic focus was from a focus coil, and a static focus was using an adjustable PM maginet around the neck of the tube.

Now that I have thought of it my 66 color roundie uses a grid in the tube for focus. Electrostatic. My 21 inch B/W uses a focus coil, and my other B/w TV uses a PM maginet for focus.

Someone help me get my ideas straight here!
Thanks!!
Matt Davala