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Congratulations to kk99 for Repair of tone control circuit in old transistor radio, gam3t3ch for Non-Electrical to Electrial issue: Battery booster pack repair. , Workshopshed for Train Repair , and Sean_Miller for Fixing R2D2's Brains .
You are the winners of the Simple Electronic Repairs project competition from Project14!
The holidays are winding down and a lot of us have probably spent a little more than we wanted to. If you have a device that suddenly stopped working, or want to give life to something vintage, perhaps the following projects will be a source of inspiration to you.
The theme for this competition was Simple Electronics Repairs and the idea came from fvan The idea is to repair a device that is malfunctioning instead of throwing it away or buying a replacement. It could be something as simple as repairing a faulty switch, or possibly save yourself an expensive repair for you to fix it yourself.
As anyone that's had a computer that they've worked on themselves, its also a great way to learn about how electronics work...
The Winners
Repair of tone control circuit in old transistor radio
As electronics have gotten more compact and parts more specialized, its gotten a lot more difficult to fix things without getting involving the manufacturer. Not so with a lot of vintage electronics. Aside from looking cool, they are often designed to be easily taken apart and contain components that can easily be identified and replaced.
kk99 owned such a piece of vintage equipment, a transistor radio called the ITT Schaub-Lorenz Touring International 103. It had a small issue with its bass control circuit that was caused by "cold joint" around the potentiometer used for bass regulation.
To get better sound on a portable radio than this German-made device you would have to step up to a boombox sized Grundig Satellit 600/650, which is 3 to 4 times its size. The ITT Schab-Lorenz Touring International produces a deep, taut bass with good definition, along with open and detailed mid-range and tremble. The reason its name is such a mouthful is because when German companies merge, they also merge their names.
Thus when International Telephone & Telegraph (ITT) merged with a company that was itself the result of a merger between Schaub and Lorenz, the new company became ITT Schaub-Lorenz. The top of the line products for the company were known as the Touring line. The 103, which was produced between 1974-1975, were often heavily used and carried about making it difficult to find a good specimen on ebay.
One reason these portable radios sounded so good is because of the history behind the companies that made up the merger. Founded in 1880, the Lorenz half of the merger was a telegraph and telephone company that manufactured speakers and amplifiers. What set helped set them apart was the fact that thoughout the 1920s and 30s they were making radio broadcast equipment and designing professional auditorium speakers and amplifiers. While the other radio manufacturers were outsourcing the speakers to other OEMs, ITT didn't.
Its dual speakers deliver a full 2 watts of power at 1% THD on batteries, 4 watts on AC, and 5 watts on external DC power. By comparison, modern radios are typically rated in milliwatts (mw) so the 2 or 3 watts is pretty much unheard of.
kk99 goes step by step to show you how he took it apart, did a short analysis of part of the schematic related to tone control circuit, and did some quick measurements of continuity to discover the cause of the "cold joint." There was no connection between the R334 potentiometer and the C388 capacitor.
Non-Electrical to Electrial issue: Battery booster pack repair.
gam3t3ch was looking to do a repair on something that wasn't video game system related. Since he's done those in the past he figured it would be too simple so he was looking for a new challenge. He had a booster pack lying around his shop. It was just sitting there, not working, for almost a year. The booster pack with compressor seemed like the ideal project. Since it was electronic and also mechanical, he figured it was fairly straight forward.
Below is video on him taking it apart and testing. He had a great time and although it wasn't on purpose, he was actually glad he blew the fuse!
Workshopshed fixed up train set that his wife picked up from the charity shop. It was broken but she had no doubt he could fix it. Upon examination he realized the train had a 6v Lead Acid battery under the seat and a multimeter told him it was quite flat. Since he didn't have a charger, he googled how to make one. He found an L200 regulator kit in the bottom of a drawer and added a high wattage "sense" resistor to limit the current. He also added a couple of bits of old PC heatsink, one to the regulator and one to the resistor and boxed it all up. This allowed him to charge the battery.
It didn't work once he was done charging so he did a teardown to get to the electronics. After fixing it he got a couple of good years out of it before he returning it to the charity shop where it sits for someone else to do a simple electronic repair!
Sean_Miller is living the dream and owns his own R2D2! He built this with the help of the gang at Astromech.net, a forum for droid building enthusiasts.
He credits that along with The Ben Heck Show which showing him everything he needed to know about mechelectronics!
Recently, his R2D2 ceased to continue working properly so he does a Ben Heck style teardown and discovery to see what went wrong!
The autonomous dome automatically blinks his lights and opens his panels in pseudo random fashion. However, recently, we noticed that after a few minutes, his panels would no longer open as designed and one of his front lights (the Process State Indicator) no longer behaved properly. The servos would just stutter and not open fully. For the light, it should light up in red, blue, or scroll from one color to the other. Instead it is either off for long periods of time or fully on with both the red and the blue making it look solid magenta. This started after I added an additional white LED to his front holoprojector.
Recently, his R2D2 ceased to continue working properly. Among other things, the panels no longer opened as designed and one of the front lights didn't work properly. So he channels his inner Ben and does a Ben Heck style teardown and discovery to see what went wrong.
He narrows the root cause of the erratic behavior and summarizes some of the most common things to consider when troubleshooting erratic behaviors with Integrated Circuits. Like the maestro himself, he goes in and fixes him!!!
Honorable Mention
In this corner of cyberspace we love everything vintage and having to do with music so we were delighted to see gam3t3ch do a 1970's Sears 8 Track Repair.
gam3t3ch won for his previous project and had time to do another awesome Simple Electronic Repair!
This was another favorite of our judges.
rsc goes step by step with you on what you need to do when the crackling and popping drives you crazy every time you turn up the amp.
"There's no magic spray that will turn grease, scratches and dirt into pure gold and silver. Spraying a bad solder joint will not make it conductive again, spraying a cracked PCB trace will not fix it." - rsc
Thanks to everyone that participated and who made this competition special once again!
Hope you folks had a Merry Christmas, Happy Hanukkah, a Meaningful Kwanza, a Festivus for the Rest of Us, or Whatever the Season Means to You!
Be sure to congratulate the winners in the comments below!
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