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
