[Heathkit] SB-630 information 2nd request - problem discovered!

[Mike McCarty]

jack m wrote:

[...]

> I took a closer look at the bad bulb, and I discovered that the
> "GE-A6" I claimed earlier is actually a "GE-AG", which ties in with
> your findings from the Glow Lamp data book.  Now, for which AG, there
> may be a clue with the color of the dot(s).  Looking very critically
> at the dot(s) complex using greater magnification, it "resembles" the
> appearance of a Venn diagram, with what may have been three color
> dots originally daubed on the glass.

Interesting.

The bulbs with "AG" in the desigation are (with "old" designators
on the left)

NE-76	5AG-A
NE-80	(5AG-A listed as a sub)
NE-81	5AG

The rest do not correspond to "old" designators, and are
3AG, 3AG-A, 3AG-B, 3AG-C. There is also the A1G which is not
closely characterized.

> The (most obscurred) one on the lower left of the triad is either
> black or green (probably black if I had to guess), the one on the
> lower right has only an outline remaining of what was most likely

I have no idea what that may mean, if anything.

> brown, and the one on top is probably red.  Looking inside of both
> the NE-2 and the AG, there is no obvious appearance of doping on
> either element.

I'm not sure you could see it.

> I sure wish I could do surgery, but the one lead is broken off up in the base.

You could try carefully filing.

> I checked the part numbers in the SB-610 and SB-620 manuals, and the
> (similar) neon lamps for each of these kits are completely different,
> although the SB-620 lists it's two neon lamps as NE-83's in the

The NE-83 corresponds to 5AH (new designation) and is a high
current lamp intended for pulse generation to fire triacs and
thyratrons, but the maximum BV listed is over 100 VDC, and
it could not be relied upon to light up in this ciruit.

> description.  No description for either the SB610 or SB-630 lamps -
> just Heath part numbers.  A check of the usual Heath parts sites has
> nothing listed for neon lamps in the 412-series of part numbers.

Not surprising. However, you should be able to find a part which
will work in the list I provided. That's assuming they are still
made :-)

> This is turning into a real detective story!

Welcome to Vintage Equipment Repair.

Mike
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