I still own one of these. It got me started On Sun, Jul 21, 2019 at 2:22 PM <[email protected]> wrote:
> 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 <[email protected]> *On Behalf Of *Chuck McCown > *Sent:* Sunday, July 21, 2019 11:12 AM > *To:* AnimalFarm Microwave Users Group <[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. > > -- > AF mailing list > [email protected] > http://af.afmug.com/mailman/listinfo/af_af.afmug.com > > ------------------------------ > > -- > AF mailing list > [email protected] > http://af.afmug.com/mailman/listinfo/af_af.afmug.com > > > > > ------------------------------ > > -- > AF mailing list > [email protected] > http://af.afmug.com/mailman/listinfo/af_af.afmug.com > > > > > ------------------------------ > > -- > AF mailing list > [email protected] > http://af.afmug.com/mailman/listinfo/af_af.afmug.com > > > > ------------------------------ > > -- > AF mailing list > [email protected] > http://af.afmug.com/mailman/listinfo/af_af.afmug.com > > ------------------------------ > -- > AF mailing list > [email protected] > http://af.afmug.com/mailman/listinfo/af_af.afmug.com > > -- > AF mailing list > [email protected] > http://af.afmug.com/mailman/listinfo/af_af.afmug.com >
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