Another look at the Heathkit GC-1000 Most Accurate Clock, analyzing why the voltage regulator is prone to failure in this design and the options you might have to make a better linear supply for one of these clocks. Added Bonus - bad technical drawing! Enjoy!
#Heathkit #fail #repair
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#Heathkit #fail #repair
Join Team FranLab!!!! Become a patron and help support my YouTube Channel on Patreon: http://www.patreon.com/frantone
- Music by Fran Blanche -
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Fran on Twitter - https://twitter.com/contourcorsets
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Hi , Great video, Would a zener diode help in dropping the voltage before the regulator ?
9V drop from 14V to 5V, times 0.3A max load current is about 2.5W dissipation worst case. That will get that 7805 good and warm but it shouldn’t be outrageous. That regulator should have had a bigger heatsink for sure. And I totally agree that a 9V transformer would have made more sense.
use one SCR pre regulator
Hello Fran. I enjoyed your video very much. It reminds me of my early years in school when
I built many Heathkit Ham Radio projects. I also built a Radio Shack Knight Kit T60 Ham Transmitter, and Lafayette's short wave receiver. Then I noticed your Fender "Telecaster" type guitar that you built. I own a few Fender guitars myself. You are a truly amazing technician. Anyway, I thought i'de drop you a note to express my appreciation for your enormous talent.
Bye for now.
Al
Wire up the transformer as if it was on 240v input but keep it on 110v input that would give you about half the output voltage and you could lose the dropping resistor it should be about right Fran x
You are so intelligent and pretty, Fran..
I have gotten lazy in cases like this and so I just added several power diodes in series to drop the voltage say 2.1 or 2.8 volts.
Fran, you don't have to excuse your self when your doing something great!
hmm, i think that voltage 17v is within the max 7805 rating, and fhe power 0.2amp at even up to 12v drop, is only 2.4 watts, and the heatsink looks reasonable size..??? with 13v actual input its 1.6w dissipation.?? strange ? maybe there was a bad batch of 7805s? i've seen these 3 terminal regulators fed raw unsmoothed dc in a server cabinet cooling controller unit, maybe to reduce dissipation?.. try that?
Wow, marry me
I have one of these GC-1000 clocks. A couple of years ago someone upgraded the power supply for me. The clock has now failed. Sadly, NO ONE on planet earth knows how to fix them anymore.
Also you can put a diode at the 110 v input so you can take half of the ac wave and you dont need a variactor and the voltage goes from the 110 to more or less 55 and at the secoundary also you get the half about 6 volts and so ac after rectified you get the 7.5 volts for the 7805 what do you think about it ?