A 40 Amp Linear Power Supply Rebuild Journey - Tripp Lite PR-40A
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- Опубликовано: 27 июл 2024
- Hopefully an educational video about rebuilding a high current linear power supply and doing some electronic sleuthing since there was no schematic to be found for one of these. Learning a little about current sensing / protection circuits and crowbar circuits.
Link to the heatsink grease I used in this video:
amzn.to/47jFvnV 
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The next video should be about checking the ripple and how to improve it. Thanks for this one.
Back in the '80s I worked on cable tv line equipment. Almost everything at that time used a '723 regulator. Thanks for the memories.
Cheers very much. Makes me want to crawl into my spare Astron and make sure it’s up to snuff. I think I was supposed to know what the crowbar does, from the Tech or General exam, but I had completely forgotten. Won’t forget it again having now seen how it works.
I have a 30 year old Tripplite PR-15. I replaced the power switch a couple of years ago, everything inside looked good and is original. I bought it new at C&G Electronics, a ham supply store, which is no longer a brick and mortar store. Funny, I was thinking I should probably recap it since I still use it . Still measuring 13.84 volts at 1 or 2 amps load, and no measurable ripple on the lowest AC setting on my digital meter. Thanks for posting this, good info.
You didn't check for AC ripple on the DC output under load. That is important in Ham Radio, it can cause a hum when transmitting. Great to see you back again.
I did, just didn't put it in the video. The video was getting long and I was more focused on showing how to figure out what a circuit did with no schematic.
Love the LM723, great device and still incredibly useful, If it's implemented properly then it's pretty difficult to beat it in a linear PSU even now, 40-50 years after it was released.
I don't want to split hairs, i think this is a great teaching video. But for the just learning viewers an scr diode when triped stays conducting until you remove the voltage across it. Once again keep up the great videos.
This is true, I should have said it that way.
great power supply and winter foot warmer.
Always good to see a vid from you Mark, even when its an all too rare thing these days.
Your channels' theme seems always to be giving the average person confidence to try things thanks to your how to style approach.
I appreciate & have benefited from your efforts over the years, even building one of your projects!
All the best to you & family over the Christmas break, hope to see more of you in the new year.
Cheers, Mick in Aus.
Terry any time you want to make videos on solid state audio is fine with me. I’ll watch
Mark, good video. Cut my teeth on 723 in the ARMY, great device for it's time. Good discussion on crowbar and current fold over. May you and your family have a Merry Christmas and happy New Year. Danny KI6VBC.
Same to you, Mark KG4FDR
That extra heavy duty diode that you removed was likely used to prevent an external battery from being hooked up backwards to the power supply. Years ago it was common practice to use these types of power supplies as a dual purpose lead acid battery charger and a 115 VAC power supply. In this manner the battery was always topped off and ready for use during a power outage. Think of it as being an early manually operated uninterruptible power supply.
Makes sense, won't see that use at my house :-)
That was a terrific episode. Great tips!
I would recommend to put back the output capacitor. I suspect that it was attached to the original terminals in the back.
Normally, the capacitor on the output would help prevent the regulator from over compensating when you key the transmitter, which would cause a sudden drop in voltage.
I have a Pyramid Phase III model PS-50 power supply from the late 70's and it looks identical to this Tripp Lite. All three circuit boards are identical. It even has the little green sticker on the transformer. The schematics are available online and should be very compatible. If you can't find them let me know and I can send them to you if you like.
Good to see you again 😊👍
Great video, thank you
That was really interesting, thank you
A before and after stress test would have been nice!!
Agreed, I should have put that on camera. Video was getting long, I'm trying to keep them to 15 min or less but sometimes its hard.
The diode is probably there because it was used as a battery charger in the past.I bet you find transistors replaced.
agreed.
I thought it would have a LM723 voltage regulator chip
Yep, you can tell that a ham owned this. Sadly, he was no Elmer.