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Old 07-19-2012, 02:14 PM
xargos xargos is offline
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Getting started in repair

Okay, so this is probably somewhere between on topic and off topic.

I've tinkered with some different electronics for a while, but other than with personal computers (which are very easy to work on since they're so modular) I've never fully delved into more than assembling kits or doing relatively basic repairs on things that aren't very high powered. It isn't for lack of interest, though, but rather not knowing where to start. I've hoped to find some classes in my area, but between the equipment that I prefer being older and a general lack of people repairing things at all the classes don't seem too common.

Where did any of you get your starts in actually fixing equipment? Was it strictly through DIY efforts, some kind of classes, or something else?
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Old 07-19-2012, 05:51 PM
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Reece Reece is offline
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I started as a kid, my Dad showed me how flashlight batteries and bulbs worked together and other simple circuits. An uncle helped me build a crystal set and I was hooked. I collected old radios and parted them out. I got books and read up and built one tube sets and then bigger ones. I experimented with operating sets and learned how they worked and got shocked and burned from drops of solder.

What I would recommend would be to get some cheap flea market five tube radios for a few dollars each. Some may "work" somewhat already, some not. Read up. There is lots of info on line, and many YouTube videos of radio repair. If you already know the basics of schematic reading, know AC from DC, know what capacitors and resistors and transformers do, here is a good tutorial that takes such a radio through all of its stages.

http://www.angelfire.com/electronic/...bes/AA5-1.html

There are lots of other sites! Google "all american five radio" and "AA5 radio" and you can read for days. With a soldering iron and a cheap digital volt-ohmmeter you can do a lot and acquire more equipment as you go along. Get good at simple radios like this and graduate to more complex devices later.
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Old 07-19-2012, 11:01 PM
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bgadow bgadow is offline
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I would do exactly what Reece suggests. Something that would be educational and also rewarding would be to get a simple, cheap 'AA5' that kinda works but hums real bad, and teach yourself how to replace the filter capacitors. I had been collecting for probably 15 years before I really fixed anything; before that it was just jiggling things & swapping tubes. I still remember that first set I brought back from the dead by changing the filters-a great feeling!
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Old 07-20-2012, 12:50 AM
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maxhifi maxhifi is offline
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I'd say I learned how to repair electronics, by NOT learning how to play baseball, etc, while I was growing up

I like the challenge of fixing obsolete equipment, it's fun because it forces you to be resourceful.

I would suggest some books about radio/electronics theory from the 50s and 60s, targeted at the vocational market. Temper that with buying old junk (like AA5 radios, or an old guitar amp, or whatever you're into but nothing too complex at first), and working on it, so that you don't get bored by pure theory. Plan to devote at least a workbench, and probably a room to the hobby, stuff seems to multiply on its own after people learn you're interested.
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Old 07-20-2012, 10:16 AM
xargos xargos is offline
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Quote:
Originally Posted by maxhifi View Post
I'd say I learned how to repair electronics, by NOT learning how to play baseball, etc, while I was growing up
Being young enough to have access to the home computers of the 1980s at an early age, this is actually pretty much how I learned to program, assemble, and fix computers!

Anyhow, thanks for all the advice, everyone.

I actually have recapped an Emerson brand AA5 (plus replaced a defective rectifier tube) that has been in the family since new. One of the first things that I heard on it was, surprisingly enough, the 1939 radio show of "A Christmas Carol." Doubtless some of the resistors have drifted, though, and without a signal generator I haven't attempted to align it.

Before that, I had assembled a modified version of the Dynaco ST-70 amplifier using new components. That was actually my first real soldering work, and surprisingly enough the thing actually worked when I completed it.

I did pick up a set of books that appears to be pretty good, but I haven't started reading it yet. It is one of the older courses designed for the US Navy, so it definitely covers vacuum tubes. Hopefully it will help me to understand the theory behind how different types of circuits work.

Besides that, I guess one of my issues is that I need to work on my confidence regarding repairing things. I generally worry that I will just make a problem worse. Then again I guess you can't learn without making some mistakes, right?
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Old 07-20-2012, 10:45 AM
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maxhifi maxhifi is offline
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Quote:
Originally Posted by xargos View Post
Being young enough to have access to the home computers of the 1980s at an early age, this is actually pretty much how I learned to program, assemble, and fix computers!

Anyhow, thanks for all the advice, everyone.

I actually have recapped an Emerson brand AA5 (plus replaced a defective rectifier tube) that has been in the family since new. One of the first things that I heard on it was, surprisingly enough, the 1939 radio show of "A Christmas Carol." Doubtless some of the resistors have drifted, though, and without a signal generator I haven't attempted to align it.

Before that, I had assembled a modified version of the Dynaco ST-70 amplifier using new components. That was actually my first real soldering work, and surprisingly enough the thing actually worked when I completed it.

I did pick up a set of books that appears to be pretty good, but I haven't started reading it yet. It is one of the older courses designed for the US Navy, so it definitely covers vacuum tubes. Hopefully it will help me to understand the theory behind how different types of circuits work.

Besides that, I guess one of my issues is that I need to work on my confidence regarding repairing things. I generally worry that I will just make a problem worse. Then again I guess you can't learn without making some mistakes, right?
Troubleshooting is a logical process, and you can avoid making the problem worse by following some basic steps. Mine are more or less like

1. First step is to understand how the device is supposed to work
2. Isolate the problem by signal tracing and process of elimination. An oscilliscope is a huge asset here
3. Repair problem
4 confirm repair by testing device with real world operating parameters

Now this is all easy to say, but every time I do it another way like substituting parts or guessing, it just makes work and wastes time (like the water pump my mustang didn't really need)
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Old 07-20-2012, 12:33 PM
xargos xargos is offline
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A decent oscilloscope (and a signal generator) would be very handy to have. With so many different brands and models of oscilloscope, some of them quite expensive, I'm not sure where to start, though. I'm guessing something like a used 20 MHz might be a decent start, but I don't want to end up with something that isn't workable, either. Any recommendations?
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Old 07-20-2012, 02:58 PM
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maxhifi maxhifi is offline
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Originally Posted by xargos View Post
A decent oscilloscope (and a signal generator) would be very handy to have. With so many different brands and models of oscilloscope, some of them quite expensive, I'm not sure where to start, though. I'm guessing something like a used 20 MHz might be a decent start, but I don't want to end up with something that isn't workable, either. Any recommendations?
Get something cheap but new enough it doesn't become a project of its own. Honestly the one I use is an early 60s Stark Instruments tube based scope which originally belonged to a high school electronics lab. I got it for free 20 years ago and it's been fine ever since for my needs. It has limitations but allows me to view waveforms and troubleshoot electronic equipment

Last edited by maxhifi; 07-20-2012 at 03:18 PM.
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