[Heathkit] SB-630 Neon Lamp update - it's fixed!
jack m
oldvette at hotmail.com
Thu Dec 9 18:26:05 EST 2010
Thanks to all who helped track down the 3AG-B neon light needed for the timer circuit of the SB-630 Station Monitor. Now that we know what we need and where to obtain it, I have an update for those interested. (Meanwhile, I ordered 3 new bulbs from the source.)
After feeling "emboldened" when the bulb type and source were found, I decided to take a flyer and attempt a repair of the bulb. Since one lead was broken off up in the base, what was there to lose? Someone actually suggested that I try to file the glass to expose the leads for micro surgery.
Well, I did just that and the result was a success which I'd like to describe to those interested. Assuming that I would break the bulb, I took a sharp, fine file and cut a shallow transverse notch across each side of the base with about 5 passes each side. During the process, the second lead broke off. Not having anything to lose, I placed a nipper pliers on the cuts with light-medium pressure, squeezed and prayed - the glass shattered right below the cuts, instantaneously exposing 1/4 inch of each lead! The bulb vacuum was still intact! A sacrificial resistor was canibalized for it's leads, and these were soldered to the bulb leads using a heat sink next to the glass - nothing special here - just laid the wire side-by-side with no mechanical joint.
I carefully tack-installed the repaired bulb back into the SB-630, again using the heat sink next to each lead repair, and it now works fine. I failed to mention that I did not note which side had the polarizing dots on it, and these disintegrated with the nipped base. Murphy"s 50-50 law did not apply here, and I hit it right the first time. I am in the process of setting the timer for 10 minutes.
Thanks to all who showed interest and provided assistance for this challenge.
Regards,
Jack W3RU
More information about the Heathkit
mailing list