Repair Memories

Back in my early teen's (circa 1970), our home entertainment electronics consisted of a series of aged B&W television sets that had been given reprieves from the garages and back rooms of neighbors and relatives, so that they might sever out a few more useful years. Inevitably, on occasion the magic box would cease working, to the consternation of all concerned.

At age 10 or 12, I didn't know much about electronics, but I had formulated a few basic rules:

Avoid getting electrocuted!
If a tube had stopped glowing, it was probably bad
If the symptom was similar to that produced by a misadjust control, any tube with a similar name was suspect.
If there wasn't a tube diagram glued to the inside of the set, and a tubes markings couldn't be deciphered, the main library had "Sam's" schematics

As I gathered experience, I also gathered a collection of tubes salvaged from deceased TV's and radios. Plus marginal ones that had been replaced. These were stored in a brown paper sack in the bedroom closet.

When a repair was needed, the paper bag was consulted for possible parts. If none were found, a trip was in order. Fortunately there was a pharmacy close by that both sold tubes and had a nice tube tester, for use by the customers.

Depending on the certainly of the diagnosis, some or all of the tubes made the trip to the pharmacy. The tube tester had a large roll chart where you looked up the number of the tube. It told you which of the many sockets to put the tube in, and where to set various selector switches. You then turned the machine on, and waited a minute for the tube to warm up. If you were lucky, the machine would tell you if it was good or bad. Sometimes it would give ambiguous results.

There was a large meter on the machine that indicated how the tube was doing. There were also a couple of idiot lights, I think one was labeled "gassy." One tube from a set might show marginal or slightly bad on the meter, on another the "gassy" light might come on. Based on experience, either might be the weak link that was keeping the TV from working.

Since labor was much more in supply than money for shotgun replacement of tubes… My introduction to gambling.

Aside from CRT's, the only vacuum tubes I own now are in an old VTVM I picked up at a garage sale years ago. It's was in a crate in my back room. It worked when I fired it up...except for the ohm meter battery, that a previous owner soldered directly into the circuit Grumble, grumble. At least it didn't leak.

Back about the eight or ninth grade, I scrapped up enough money to buy a multimeter from Radio Shack, the cheapest one they had, less than $10. It did not last long, as I tried to measure 115 VAC with it set for a current reading. An expensive lesson at the time. Eventually I scraped up the money for a replacement.

I own four multimeters, this one probably gets used most often. If I take one on a trip, it's this one. If I need a quick check on something, it's usually the easiest to get to get to, plus I don't have to figure out the any control buttons, like I do with the DMM's.

The only maintenance it requires is a new AA battery every decade or so. Even if the battery's almost dead, it's good for a quick continuity check. Once I had to replace the test leads, the plastic insulation cracked up.

The meter cover is cracked from when it was dropped, and it has a few holes drilled in it from an experiment where I needed to connect something directly to it's lowly 1 ma movement; it still works.

If it ever dies or gets stolen, well, Radio Shack still has a similar model in their catalog. It's up to $14.99....

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