http://www.radioshackcatalogs.com/html/1969/hr124.html
It was still kicking around a few years ago.
That was probably the best xmas gift my folks ever gave me.
*From:* Ken Hohhof
*Sent:* Sunday, July 21, 2019 11:21 AM
*To:* 'AnimalFarm Microwave Users Group'
*Subject:* Re: [AFMUG] OT 50 years ago
I had a Knight 12-in-1 lab kit (page 65 in the catalog).
https://www.americanradiohistory.com/Archive-Catalogs/Allied-Catalogs/Allied-Catalog-1963.pdf
I also remember taking tubes to the drug store with a tube tester. Often
a TV had several tubes of the same type (6SN7 or 12AX7 or 12AU7) and you
could just play musical chairs until the weak one ended up in a less
critical location. That or you called the TV repairman to come out to
your house. Once the transistor sets came out though, he would always
say “the board” needed to be replaced, and at that point you might as
well buy a new set.
*From:*AF mailto:[email protected] *On Behalf Of *Chuck McCown
*Sent:* Sunday, July 21, 2019 11:12 AM
*To:* AnimalFarm Microwave Users Group mailto:[email protected]
*Subject:* Re: [AFMUG] OT 50 years ago
I spent hours at 2 am trying to improve the convergence on my parents
color set as that is when the test pattern were on.
I used to feed audio into the vertical deflection coils of old B&W TVs
trying to make a rudimentary oscilloscope. Probably was all of 10 years
old at the time. Kids used to have much more fun than they do now. I
also had saltpeter...
*From:*Bill Prince
*Sent:*Sunday, July 21, 2019 10:05 AM
*To:*[email protected]
*Subject:*Re: [AFMUG] OT 50 years ago
Black and white TVs just shot one beam; color would shoot 3 beams. The
beams would just go straight out to the center of the screen without any
steering. That's why one of the failure modes was just a glowing dot in
the center of the screen. Steering was done with electromagnets in the
form of a "yoke" wrapped around the neck of the CRT. One pair for
horizontal scan, and one pair for vertical scan. Black and white was
pretty simple, but color had all kinds of issues because the 3 beams
could not be concentric, they were closely-spaced parallel beams.
I forget what tool we used once to measure the radiation from the front
of a CRT, but it wasn't much. In fact, it was almost undetectable once
you got more than an inch away.
bp
<part15sbs{at}gmail{dot}com>
On 7/21/2019 8:36 AM, Chuck McCown wrote:
I got a thumb into the HV on a TV once. Felt like a dull twisted
awl that was red hot being jabbed into my thumb. Not a feeling of
shock at all.
Yep, once I discharged my first CRT I got over the fear and then
kinda looked forward to doing it. I don’t remember triplers,
seems like there was an HV rectifier tube. Maybe it was just a
chopper that fed the triplers or stick rectifier. I always
presumed the tube did the job. Maybe the tube just made the
horizontal scan?
*From:*Ken Hohhof
*Sent:*Sunday, July 21, 2019 9:23 AM
*To:*'AnimalFarm Microwave Users Group'
*Subject:*Re: [AFMUG] OT 50 years ago
I think it could be as high as 30 KV. Hard to believe we all had
these things in our living rooms. Between the high voltage, the
X-rays (stopped by thick leaded glass at the front), and a big
glass tube with a vacuum inside and a fragile neck.
I worked a couple years in the 70’s for Warwick Electronics, which
made TVs for Sears and Kmart. Before you worked on a set, you had
to discharge the CRT which was like a big capacitor and would hold
the charge for awhile. The engineers and techs there would break
off a length of solder, hold one end against the chassis, and hold
the other end against a big flat bladed screwdriver which they
would shove under the anode cap with a Zap sound. I was not brave
enough to do it that way, I would at least use a wire with
alligator clips at each end.
BTW, the lingering charge problem was worse when they replaced
went to triplers instead of stick rectifiers. A voltage tripler
is basically a bunch of capacitors and diodes.
We also had an electrostatic voltmeter to measure second anode
voltage. It was on a rollaround cart and had a vacuum inside and
the voltage was measured by the deflection of a needle based on
the electrostatic repulsion of two plates. Another capacitor, and
it could hold a charge for days. It was referred to as “the dog”
because it was the size and shape of a medium size dog, had a
snout where the high voltage probe went in, and it would bite you
if you weren’t careful.
We had a high voltage engineer who died of electrocution. Not at
work, but at home, from his ham radio transmitter. Heart stopped,
wife called 911, but they didn’t get there in time. Live by the
sword, die by the sword.
I was told that most serious accidents from CRTs come not from the
shock itself, but the shock would cause your arm to jump and break
the neck off the CRT and you would get cut by the glass.
*From:*AF mailto:[email protected] *On Behalf Of *Bill Prince
*Sent:* Sunday, July 21, 2019 8:56 AM
*To:* [email protected]
*Subject:* Re: [AFMUG] OT 50 years ago
I don't recall what the voltage was on black and white TVs.
Probably somewhere in the range of 10K - 15K volts. Early color
TVs could be as high as 25K volts. Aquadag is the term for the
metal coating on the inside of CRTs. High positive voltage is
applied to it to bleed off all the electrons being shot at the
screen. In those days we called the high voltage circuit and
whatever voltage as just "aquadag".
bp
<part15sbs{at}gmail{dot}com>
On 7/20/2019 7:38 PM, Chuck McCown wrote:
Yeahbut, they all did it, especially the color TVs. I presume
aquadag is autocorrect for Anode.
*From:*Bill Prince
*Sent:*Saturday, July 20, 2019 5:18 PM
*To:*[email protected]
*Subject:*Re: [AFMUG] OT 50 years ago
The aquadag HV on early TVs was a common source of problems.
Get a little dust on the top of the TV's cathode tube, and
you'd get these periodic "snap!" sounds when it would
discharge through the dust.
bp
<part15sbs{at}gmail{dot}com>
On 7/20/2019 12:49 PM, [email protected] wrote:
It was TV of the mind. I didn’t want to risk going into
the house on the off chance that the B&W TV would actually
work. It was terribly flakey. Had some kind of HV
problem where it would go very dark after a few minutes.
So I stuck to the radio.
*From:*Bill Prince
*Sent:*Saturday, July 20, 2019 1:16 PM
*To:*AnimalFarm Microwave Users Group
*Subject:*Re: [AFMUG] OT 50 years ago
We had a Buick too, but ours didn't have a TV, so we had
to watch it on our black and white TV in the house.
--
bp
part15sbs{at}gmail{dot}com
On Sat, Jul 20, 2019 at 8:53 AM Chuck McCown
<[email protected]> wrote:
I watched the moon landing on the radio of a 1965
Buick Special.
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