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

Wed Dec 8 19:26:37 EST 2010

The 1984 Heath Master Parts lists shows the 412-34 as follows:  62.0 V, .40 MA, #3AGB

Tom K3TVC

From: jack m 
Sent: Wednesday, December 08, 2010 5:13 PM
To: tchesek at epix.net ; mike.mccarty at sbcglobal.net ; heathkit at mailman.qth.net 
Subject: RE: [Heathkit] SB-630 information 2nd request - problem discovered!

Hi Tom and the rest of the group,

I did get a copy of the SB-630 Monitor parts page from a list member.

The number for the SB-630 neon light is 412-34.  Description is simply, "Neon lamp".  Perhaps someone has access to the Heath Master Parts List which would spec this component and cross-ref it to a familiar GE GLow Lamp or other type.  

I could not find the part referenced on the "regular" parts links commonly available to us.

The SB-620 parts list at least stated the lamp used in that kit was the NE-83, in addition to the "Neon Lamp" description.

Thanks to all who have helped so far.  I may attempt to expose a piece of the broken lead if all else fails - (never filed glass before).

Jack  W3RU

> From: tchesek at epix.net
> To: oldvette at hotmail.com; mike.mccarty at sbcglobal.net; heathkit at mailman.qth.net
> Subject: Re: [Heathkit] SB-630 information 2nd request - problem discovered!
> Date: Tue, 7 Dec 2010 18:56:44 -0500
> 
> Does the SB-630 manual give a Heath part number and if so what is it?
> 
> Tom K3TVC
> 
> 
> 
> -----Original Message----- 
> From: jack m
> Sent: Tuesday, December 07, 2010 6:33 PM
> To: mike.mccarty at sbcglobal.net ; heathkit at mailman.qth.net
> Subject: Re: [Heathkit] SB-630 information 2nd request - problem discovered!
> 
> 
> Hi Mike,
> 
> This certainly is a comprehensive analysis you have described to the list.
> 
> I received a parts list from a list member which has added to our resources.
> 
> 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.
> 
> 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 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 sure wish I could do surgery, but the one lead is broken off up in the 
> base.
> 
> 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 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.
> 
> This is turning into a real detective story!
> 
> All help is greatly appreciated. What a resource this reflector is!
> 
> Regards,
> 
> Jack W3RU
> 
> > Date: Tue, 7 Dec 2010 14:26:33 -0600
> > From: Mike.McCarty at sbcglobal.net
> > To: oldvette at hotmail.com; heathkit at mailman.qth.net
> > Subject: Re: [Heathkit] SB-630 information 2nd request - problem 
> > discovered!
> >
> > jack m wrote:
> >
> > [...]
> >
> > > So I figure this is NOT an NE-2 in the SB-630. With the NE-2, the
> > > ID/buzzer just goes on and stays there, but can be released with a
> > > plastic tool prying up on the relay. Without the NE-2, the reset
> > > button will pulse the relay on/off.
> > >
> > > Upon magnified inspection, I see a "GE-A6" cast into the broken
> > > bulb's base, whereas I see a "GE" and "2" on my ten neon spares.
> >
> > I've got a copy of the GE Miniature Lamp catalogue, and it doesn't
> > list a GE-A6. So, I pulled my copy of the GE Glow Lamp book, and
> > looked in the specs section, and there is no GE-A6. It gives
> > both the "old" and "new" designations.
> >
> > > Just a copy of the parts list would be very helpful, as well as any
> > > insight to the neon bulb used in the relay circuit. Any pages from
> > > 29 on back would also be appreciated. Many thanks to those who have
> > > helped so far.
> >
> > It's probably not going to be helpful. It'll probably just
> > say it's a selected neon bulb with a dot.
> >
> > Let's look at the circuit and try to figure out what it does.
> >
> > C23 and C24 start out discharged, and the lamp is off. The
> > caps charge up through the 144 Meg resistance until the voltage
> > across the lamp is sufficient to make it fire. The sudden
> > flow of current causes the voltage at C22 to jump, and this
> > gets passed along to the tube grid, pushing it into conduction,
> > and energizing the relay.
> >
> > When the relay pulls in, the charge on C23 and C24 gets dumped
> > to ground through current limiter R28, with a time constant of
> > 4 ms, that is, nearly instantly. It would be about 20 ms to
> > complete discharge. At that time, the voltage is mostly
> > from the 220K R33, hence only about 1/2 % of the
> > voltage on the pot. At this time, the voltage from the pot
> > through the 220K resistor must be less than the maintaining
> > voltage of the lamp.
> >
> > So, the lamp is part of a relaxation oscillator. It's probably
> > a selected one, with a known breakdown voltage and resistant
> > to "dark effect", possibly with a coat to imcrease leakage
> > resistance (it's in a 140Meg circuit, after all).
> >
> > The 0A2 regulates somewhere between 140 to 168 V. That means
> > that the range of voltages on the pot are
> >
> > Vreg. Range on pot Across Bulb
> > ------ ------------ -----------
> > 140V 54.6 to 57.4 V 82.6 to 85.4 V
> > 168V 65.5 to 68.9 V 99.1 to 102.5 V
> >
> > So, we need a bulb which is pre aged and has some radioactive
> > material for stable operating characteristics, and likely
> > a coat for low leakage. It must be able to fire reliably
> > on less than 82.6 V, and must extinguish reliably when
> > the pot voltage is applied through 220K. The latter requirement
> > is a little harder to figure, since the supply has an
> > impedance I haven't figured, but is something on the
> > order of 90K. We'll just look for lamps with an extinguishing
> > voltage close to the maximum strike voltage (reduced operating
> > range).
> >
> > Looking in the GE glow lamps, I find these as candidates
> >
> > Initial Dark BV
> > --------------- Extinguishing
> > Bulb Min Max Voltage (250K)
> > ---- --- --- --------------
> > 3AD 65 80 50 edgy high BV, good candidate
> > 3AG-A 60 80 50 edgy high BV, good candidate
> > 3AG-B 65 73 50 sel. 3AG-A, excellent candidate
> > 3AG-C 68 76 50 not as good as 3AG-B
> > 5AB-A 60 80 50 cheapest preaged, good candidate
> > 5AB-B 62 72 50 selected 5AB-A, excellent candidate and low cost
> > 5AB-C 68 78 50 selected 5AB-A, excellent candidate
> > 5AG 64 80 50 good candidate
> > 5AG-A 68 76 50 excellent candidate
> >
> > My best guess is that for the lowest cost most likely to
> > succeed lamp, try the 5AB-B, if you can find one. Next best
> > is probably the 3AG-B. Anyway, this table should get you
> > in the ballpark for a lamp which will work.
> >
> > Try not to handle coated bulbs very much. Oils etc. from
> > your hands may compromise the leakage resistance.
> >
> > HTH
> >
> > CC: original poster
> >
> > Mike
> > -- 
> > p="p=%c%s%c;main(){printf(p,34,p,34);}";main(){printf(p,34,p,34);}
> > Oppose globalization and One World Governments like the UN.
> > This message made from 100% recycled bits.
> > You have found the bank of Larn.
> > I speak only for myself, and I am unanimous in that!
> 
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