[Heathkit] SB-630 Neon Lamp update - it's fixed!

[Paul Kraemer]

Excellent Jack
May I add that before installing these fragile bulbs, or prior to working 
with the yet unbroken ones, I apply a small gob of high temp epoxy to the 
base to build  a bit of protection between the lead and the glass
Paul K0UYA
----- Original Message ----- 
From: "jack m" <oldvette at hotmail.com>
To: <heathkit at mailman.qth.net>
Sent: Thursday, December 09, 2010 5:26 PM
Subject: [Heathkit] SB-630 Neon Lamp update - it's fixed!


>
> 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
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