1970's Color CRT substitution
 

I haven't been having any luck finding spec sheets or data books on the later rectangular color CRT's. I have a couple of questions on substituting CRT's in early 70's Zenith TVs.

Is the only difference between the 25VAMP22 and 25VDMP22 the dark tinted front safety glass?

The reason I ask is that I have a 25GC45 Chromacolor II with a 25VDWP22 that's showing its age, and I'd like to swap out the CRT if it becomes my daily watcher. My Sams tube sub book lists the 25VDM as a sub, but not the 25VAM. The original 25VDW doesn't have the dark tinted glass, so there must be another reason only the 25VDM is listed.

Could the difference be in maximum anode voltage rating? The 25VAMP22 is used in a mostly tube set 25CC50 with 25 kV high voltage, while the Chromacolor II runs 29.5 kV.

Has anybody successfully put a 25VDMP22 into a Chromacolor II?

i ve done that swap.this makes a stunning picture.25vdmp22 looks even better in a flat chassis zenith.

First all CC tubes probably used the same envelope so physically
should work. CC tubes differed in dot size, screen tint & HV rating.
The KV rating is probably just the amount of lead in the glass.
Besides the HV actual gun voltages should be the same.

I would NEVER use a lower KV rating in a customers set.
If it were mine I might. Like I have said I spent 40 yrs surrounded
by sets & I dont have 3 legs & 2 feet !

73 Zeno:smoke:
LFOD !

For what it's worth:


Basing is the same, but there may be mechanical differences ("E" notation on sub...), and most likely slight. Longer neck on the VDW - we're talking 22.065" from faceplate to tip, vs 21.805" for the VDM...

All other dimensions are the same, same basing, same max KV, same safety specs, per RCA's Picture Tube Product Guide (PIX-300J), November 1975

:sigh: You lost your third leg ??? oh you poor poor guy ......

:D

If you take enough of those men's pills they advertise on TV, they claim it may grow back...Might even grow a 4th leg as a side effect. :D

Thanks, Brian,

I think I finally tracked down the last of the intermittent problems with my Zenith 25CC50 hybrid set, so the VDM gets to stay in there a while longer. It's good to know that it's a viable replacement for the CRT in the 25GC45 CCII, which it might need if it becomes my daily watcher.

I've often wondered if it was possible to replace an inline gun tube with a delta gun tube.

Nearly all inline gun sets lack the provisions (transformer windings) for driving dynamic convergence....You'd have to redesign the set around the CRT or live with lots of RGB splay at the edges of the screen.
HV and gun wise it is not impossible... I have a delta gun CRT test jig that was kept in use into the inline era and had adapter designs and settings for inline sets.