Dewalt Radio Repair

We’re suckers for repair videos and this Dewalt worksite radio repair (YouTube Link) from Hackaday alum [Todd Harrison] is no exception. Like a detective story, we’re always trying to guess who did it.

In his first video [Todd] traced the issue down to a faulty 6 volt regulator which was pushing out 8 volts. He fixed that by hacking a LM317 into the circuit to replace the original non-adjustable part. That helped but after a few days the radio failed again. So here he traced out the voltages to find the second culprit. Along the way, we get to see some of the nicer features of his Fluke 87 and 289 meters. As well as puzzling over the some of the design decisions in the radios construction, before identifying the final issue.

We won’t spoil the surprise, but find out how Todd solves this riddle, wrapped in a mystery, inside an enigma in the video below!

 

18 thoughts on “Dewalt Radio Repair

  1. Very Solid Workover ! I’ve never thought of the upside down duster can as a chilling device. I always just put things in the fridge and retried after chilling to test for heating issues. Very impressed!
    Anybody have incite into why the 10 ohm resister was placed before the amp?

    1. The resistor in combination with the capacitor provides supply line isolation for the op-amp. The op-amp is probably providing one of the first stages of amplification which is handling very weak signals and needs a very clean power supply to avoid noise and self oscillation. Self oscillation can occur when the power amplifier causes supply line fluctuations that are then re-amplified by the op-amp. The resistor and capacitor block those fluctuations from the op-amp.

  2. That was a really interesting workup, really impressed. Anybody know why there was a resistor? Not really sure if the op amp needed it unless the “official voltage” was slightly lower than the regulator.

  3. Nice detective work finding and fixing the problem, but the real mystery is why? Those things are major POS, neither a good radio nor a good charger and way way way too expensive. Hopefully it was a dumpster find and not a cold cash purchase.

  4. Great video, I think you should put more repair, troubleshooting articles up.I am just learning myself at the moment and sometimes the best way to learn is to fix a problem.

      1. Thanks this will be a great help, that site look like the sort of stuff I am after. I am teaching myself, I have just set a stepper motor driver on fire and nearly electrocuted myself the other week. So video repair’s are great to learn technique and how to do it properly.

  5. I loved this little radio, worked great in my collage job
    But radio died quickly in the minds of a group of collage kids working hanging drywall, i stuck a cheap “hijackable” Bluetooth module before the amp and worked a treat
    The thing has been dropped 4 stories and still chooches

  6. There are close to billions of car radios out there and in the great dumpster. They all run on 12v. They all will woop ass over the crap battery power jam-box with a ferrite AM antenna. They come in a steel box, not a board bridged across plastic case supports.
    Some of this surface mount stuff sometimes makes the thermal or magic mood component take you for a ride.

  7. Although I enjoyed this video, and acknowledge his methodology, I have to say this, I am basically self taught, just like a lot of us here. One of the first things I learned was “look for something that doesn’t look right” such as cold solder joints, bulging caps, burn marks, etc. As soon as he flipped over the board and showed the residue, I would have scraped it away, visually inspected it and then put my meter on the two nearest points.

    Probably not what they teach to be an EE, but I haven’t burned my house down yet.

    1. They don’ teach much electronics for an EE degree. Its sort of up to you to take extra courses / labs to do that. And sadly, not near enough EE’s bother. This is a techs job anyway. EE’s are paper pushers and test instrument jockys.

  8. who would have thought that the glue used would damage the traces.

    a good quality radio would use hot glue like you can get for craft use to hold the parts or even use zip ties or extra thick plastic supports.

    you did the right thing by unplugging before opening since until you know where the mains power is located you could get zapped just opening the device.

    that radio may have been made under black and decker ownership because dewalt would probably have used better means to hold the parts.

    1. That radio was certainly made under Black and Decker ownwership. Black and Decker bought DeWalt over 50 years ago, in 1960. It is extremely likely that every DeWalt tool you’ve ever seen was made under Black and Decker. It is also a great certainty that every single DeWalt cordless power tool that anyone has ever seen was made under Black and Decker, because all of them were, and all of them will be for the foreseeable future.

      In other words, DeWalt is to Black and Decker as Chevrolet is to General Motors.

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