Re: 15GP22 Rebuild Attempt in France - Soon!

[jhalphen]

Good day Gentlemen,

15GP22 Rebuild Attempt Progress Report - 10/15/1009

A 15GP22 CRT kindly donated by Steve McVoy (ETF Museum) is currently at the RACS factory in the south of France awaiting imminent rebuild.

The CRT was broken and therefore down to air. The RACS team after careful UV exciting of the screen + close physical examination decided that the screen/Bulb/shadow mask assembly was sufficiently intact to be worth an attempt at rebuilding. In spite of being "down to air" for a considerable amount of time, the shadow-mask is not corroded, eaten by rust, nor by other contaminants. RCA made them tough!

Friend John Folsom Jr is very kindly donating one 15G stem assembly for the attempt. Thanks to him, we are advancing the rebuild schedule by 6-8 weeks, Big Thanks! John, and Kudos! to you.

Leakage detection is accomplished, not by Helium leakage detection (Thanks! to John Yurkon for describing the process/needed gear) but by a more mundane process developped from industrial practice:

The CRT is submitted to rough 1st stage vacuum pumping, using a centrifugal pump. The final anode & therefore internal Graphite layer is energized at a 30-40KV EHT. The operator, using thick EHT-Proof gloves has an array of fine "needle-point" search electrodes with which he searches on the outside of the glass enveloppe. At a leakage point, however small the hole may be, the EHT arcs over and pinpoints the hole. It it then covered with "chewing-gum" consistency Frit-Glass, which after baking at 400°C becomes tough as a bathroom/shower tile.

RACS has a Helium leakage detector, but Tech Manager François quoted "we never use it, our method is faster & hassle-free".

The gun has been rebuilt. We are awaiting John's Stem/Base to transfer the rebuilt gun to the new base. Glassworks are now complete. The new gun neck is ready and the broken bulb neck has been sealed to avoid further contamination.

I will travel to the RACS facilities to personally watch & photo-document this first historical attempt on European Soil. If the rebuild is successful, the RACS testing facilities will display a rectangular white raster on the 15GP22's screen.

The rebuilt CRT will be shipped back to the donator (ETF Museum) for incorporation into a test CT-100 operational chassis for the first pictures of a live video display.

Thanks! for bearing with me so far, will update this topic as time runs its course.

Best Regards

jhalphen
Paris/france