Hello Gentlemen,

An RCA 621TS TV i purchased at ETF 2011 was recently restored. In spite of all normal CRT electrode voltages and a healthy 7KV EHT, no raster.

The ion trap magnets were photographed to memorize the original position then tweaked in all 4 quadrants: still not the slightest hint of brightness.

I think the CRT is toast, will try to check with a Leader CRT tester/rejuvenator before giving up. I hope it has an adequate connector for this antique.

In the meantime, i am initiating research on a working 7DP4 CRT.

Rare or common?

Recommended substitute? - with or without modifications?

Anyone got an operational tube for sale? - PM please, including shipping cost from USA to Paris/france & payment method (PayPal ?)

Thanks! in advance for any help,

Best Regards

jhalphen
Paris/France

Sorry, i don't have one, but I believe a 7TP4 will also work. It's the aluminized version of the 7DP4.

Good luck!

PM sent.

Are you using the original Elctromagnetic Ion trap?
It's possible it's defective, you can try substituting a standard PM trap.
It requires a double trap same as the 10BP4, the small magnet goes towards the front (or the small coil if it's an Electromagnet)

There is a Military tube that is a perfect sub for the 7DP4, it's aluminized and requires no trap, it's also about an inch shorter and has a different focus voltage, although grounding the focus pin seems to work just fine.

Fair Radio Sales was selling them but a collector bought them all up and was selling them to owners of 621's.

Here's an article on them from the ETF. http://www.earlytelevision.org/7dp4_replacement.html

Here's a link to the guy who has them, don't know if any are left.
http://www.videokarma.org/showthread.php?t=248421