ASTRON RS-35A Power Supply Repair
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- Опубліковано 2 тра 2015
- This video addresses some issues with an Astron RS-35A power supply. Learn a quick way to see if the pass transistors are all working. Also an explanation of how linear power supplies operate.
- Наука та технологія
I must apologize. I'm pretty sure I was the one who made these changes 20 years ago. In my defense I was a teenager at the time. We used whatever we had on hand, hence the the series resistors and reused TIP41. I moved the transistor to the other side in an attempt to give it a cooler location. I don't know what we were doing with R4, but I think we wanted something physically larger and higher wattage. It's nice to see a proper repair finally done!
It appears that making do with what you had worked for a good long time. Apparently the real problem at this time was the fatigued connections on the pass transistors and inadequate heat sink compound. Neither of those were your fault. Materials fatigue and corrode with heat and time.
I'm working on this type of circuitry from time to time, and in our business - this type of dialogue is just out of discussion, there's absolutely a different perspective about doing these jobs and why. (Guess what, stereotypes about electrical/idraulic workers in italy)
But yeah,
That's just a beauty to stand there, drink your coffee, and enjoy watching Mr Carlson making the essential moves and taking back stuff to roar
Are you being serious or funny? Did you really have a hand in the design of this power supply?
@@georgeowen2083 I believe the gentleman is saying that he may have owned this particular power supply at one time and made the repairs with materials and methods on hand and available to his limited resources.
pretty cool story to see your work on mr carlson's YT spot.
I was the purchasing agent for a fairly large commercial electronics, two-way radio, and towboat marine electronics sales and service company. I bought a ton of Astron power supplies, and they were fairly reliable. I've been retired for fifteen years, so my comment my no longer apply, but, the biggest failure we found was the SCR shorting out as it was not adequate. Our service manager asked me to source a higher value SCR, and the failure rate went way down. I don't remember what I bought at this point in time, but our customers were a lot happier. Thank you for your excellent video.
Watching this video takes me back to 1970 and my first real job at Control Data testing linear power supplies. The crowbar circuit was used on the +5v ps which had several 2N3055 pass transistors on large heat sinks. Once an assembly girl got a ceramic electrolytic in backwards and we had a nice bang and shower of debris! I moved on to testing logic cards using a GR logic tester powered by a PDP 8 but that is a story for another day.
Enjoyed the video. Finally someone around who can talk tech in plain English and make it understandable. Being in engineering for 40 or so years and retired not many people to talk to these days and who makes it straight forward.
Simply want to say, with all sincerity, thank you for the time, care and effort that you put into this and all your videos.
You are performing a great service to the art and science.
And instructing all how to be A--N--A--L. Loosen up a little. Get your fingers a little dirty, and don't freak out about it!😆😆
I love that the vacuum tube volt meter has earned a place on the bench, working side by side with all the newer, modern technologies. It just goes to show how well electronic devices and appliances were designed and manufactured back then.
DJT183 Thanks for the comment DJT183! That VTVM is a great piece of gear.
It's really nice to see that their are techs around that repair things right and do what they can to improve on the design.
Jason Burt Thanks Jason!
Jason Burt I think he must be an engineer.
there
Mr Carlson's Lab , Since I just bought a new Astron RS-35M supply and their schematic appears to be an old one, I wonder if you could comment on possibly making this a four terminal supply and running the feedback leads from the supply to the load, which in this case is an Icom 7300. de KQ2E
Still open to modifying my power supply to a Kelvin connection.
I wish I found this channel before now. You are an amazing teacher, and your videos are fantastically informative. I’ve got three or four power supplies that I’ve had stuck in a corner needing fixing. With your teaching, watching your videos a few times, I now know what to like for, and how to test it.
Welcome aboard!
I really love your videos. Who would have known that you’d learn something new on a venerable linear power supply? Not only do you fix the problems, you undo other people’s ghetto hacks as well for the longevity of the system! The world truly needs more techs like you!
For late comers, the Astron supplies are pretty much the same as far as the regulator board is concerned. The larger linear supplies have bigger transformers and filter caps. There are sometimes some additional resistors added at the factory. These are shown as "Rx" on the schematic. Also, the transistor Paul replaced is typically a TIP29A.
Have learnt all this from Paul's video and documentation and fine articles on The Repester Builder's web site in the process of reviving an RS-20A I scorched. Paul did not make the mistake I did. He went straight to the pass transistors and checked them out. I got fooled and screwed around with the regulator board. (Oh well, at least I know how it works now and am certain that the new parts I replaced are good.)
But, if you still cannot find any problems, pop in a new LM723 chip (they're socketed) and that might solve the problem.
My dad had the same one, or one very similar. It gave many years of faithful service running his ham radio at home; it was on 24/7. He gave it to me a few years ago, and although I don't regularly use it, it still works when I do. Thanks for doing a video about it.
5 years later! Still enjoys it!
Thanks
So, its under thermal throttle. Most power supplies repair starts with checking capacitor, transistors and diodes. These seems to be the weakest members in the link. I think I am correct. Your videos are excellent and you never seems to miss even minor subtle things. I wish all teachers are like you. I hope I will become a patron and be your student in future. Thank you.
Ah ! The old faithful LM723 - I worked on PSs way back in the early 80's with this IC... always a favorite. A pretty straighforward repair video. Well done.
Thank You For These videos, I really appreciate them as they help me to remember how to investigate & repair.
After 35 years in the Air Force crewing jets, my electronics skills have some what disappeared in my mind. Thx Again.
Happy to help David!
you have some gorgeous equipment in your workshop, & your attention to detail is something I admire. I'm really pleased I discovered your channel.
Rubus Roo Thanks for the nice comment! Stop by the channel any time.
+Rubus Roo
He (Mr. Carlson) is remarkably skilled. I would have come away with a lot more from highschool if all the teachers were like him.
Same here
We had a lot of Astron power supplies just like that one. If the ac power failed, the power supply would stay off when the ac was restored, until you cycled the on/off switch. As usual, your attention to detail is superb.
There's a right way to repair electronics, then there's kludges. Thankfully, you know how to repair them right. Thanks for the vid, great job.
Quantum Leap Thanks!
I have a Pyramid supply in a box in my basement that I worked on about 20 years ago. At the time someone told me they thought its problem was the transformer as Pyramid had a reputation for developing internal shorts in the windings. You have inspired me to pull it out and take another stab at it this winter.
You're talking about output transistors and mica insulators. A friend of mine used to be the sound engineer at a local disco ( way back when) He needed four really big power amps to drive the whole sound system. Two of the amps kept failing. These amps were supposed to be top of the line, thousands of $'s. come to find out, the output transistors were supposed to have mica insulators on them with thermo grease on them too. The designers removed the need for the mica wafers and just had the grease. The grease didn't quite keep everything insulated so the transistors shorted and failed. The friend finally replaced them with Crown amps that worked flawlessly.
This has inspired me to drag out an old Astron RS-35A that's been sitting defunct in the closet for nearly a decade. A well done course on the inner-workings of a timeless classic. Thanks!
Watching this second time because the repair was that good!
If everyone worked like this, there would be a lot less vintage electronics in the landfill...
Mr Carlson's Lab
Thank you for explaining how things work and teaching. I learned how power suplys worked with this.
Great! Thanks for your comment.
The Astron power supply is done and the owner is happy and Paul is happy, but we are sad, because it's over. Thankfully I still have a back log of awesome video's to watch. So really I'm still happy. :)
Great William. Working on another video right now, (burning the candle at both ends) hopefully it will be up soon. These detailed video's take a long time to complete.
Mr Carlson's Lab I can only imagine! Thank you for all you do Mr. Carlson. BTW I really like the lighting in your lab. There is no substitute for the warm glow of incandescents. I think about that every time I watch one of your videos. I can imagine it's real cozy back there surrounded by all that fantastic gear.
William Hayden hahahha same here !!!
This came just at the right time, my RS-35M is down and now I know what to look for. I already ordered new transistors to replace the Chinese junk that someone installed before I bought it and the voltage regulator chip that was replaced by one I can’t find online. I just wish I could find the correct schematic for mine, Astron only has the one prior to my design and the one after… Thanks for the great explanation of the power path and what to look for.
73 WP4TGK
It's always nice to watch a professional at work. Great videos
I love that the vacuum tube volt meter has earned a place on the bench, working side by side with all these newer, modern technologies. It just goes to show how well electronic devices and appliances were designed and manufactured back then!!
DJT183 Every bench should have one!
Typically they have very high impedance, good for low resistance measurements or to not load things down. It's an application where the vacuum tube is very welcome.
Mr. Carlson, your attention to detail is impressive, as always.
Nice video Mr Carlson , thanks for making it
Power Supplies are a passion for me
Got to love repairs that don’t require any parts just some clean up and thermal compound.
Excellent video! I love your clear explanations and attention to detail. I have owned a few Astron power supplies. One was the 30 amp version of this exact PS. Very interesting to see inside of one and it's layout explained. Your videos are awesome. Thanks!
Mr Carlson, you have too much gear on that bench. Oh, I mean you need a bigger bench.
Seeing people take pride in their work never gets old. Worth every cent. I'm guessing you get a fair bit of repair the repair going on.
Great visual explaining the importance of thermal conduction. Thanks Paul
This is great. I love these linears, they are one of the most popular bits of kit around here for all the amateur radio types.
Yes I did enjoy your very detailed description of the Astron power supply, I have one myself so I really appreciate your description of the power supply circuit and all the comments about properly servicing it. Thank you.
Very nice detailed description of the workings of this ham power supply Paul!
Also, very good down to earth troubleshooting and repair.
Another excellent video. Love it.
Tom
***** Thanks for the nice comment Tom!
oh, Mr. Carlson. I got an astron 20amp that's not working. Now I have an HF rig without a built in power supply, I searched "Astron power supply repair" and sure enough here you are! :)
Thank you.
I am a big fan of your no nonsense skill in logical repairs,best regards Colin.
Thanks Colin!
Another great video Mr Carlson. Your thoroughness, knowledge, and communications skills make you a natural instructor. Looking forward to the nest video.
Todd Anonymous Thanks for the nice comment Todd!
This is another great video mr Paul. Lot of things and trick I've got. Thanks 👍👍
Thank you Mr. Carlson! I have one of these power supplies and the cover is still on. The circuit looks similar to the one described in the 1988 ARRL handbook. Similar specs with crowbar protection. If the time ever comes for service this will be great reference.
Really enjoyed this one. Thank you for a well done video. Please keep doing more power supplies. I have as special interest in them.
Incredibly good video, methodically going through all the steps to permanently fix the supply and keep it running, and lots of helpful electrical tips for working on high-current applications (never knew the trick about keeping a short wire across a high-capacity cap while working on the rest of the circuit). Loving your content, keep 'em coming!
Andrew Kowalczyk Thanks for the nice comment Andrew!
Another awesome video Paul! Great explanation. Looking forward to you next !
TRXBench Thanks Peter!
Thank you Mr. Carlson. Very good explanations about this power supply. Very good video too!
Thanks!
Wow, a 30 minute lesson that I'll always remember. I'm not an electronics tech. Just a ham operator looking for information about the Astron power supply. Fascinating lesson; thanx!
+John G
Your welcome John!
I've had an Astron RS-20A running since 1992! I'm really enjoying your videos! :)
Overlin Alaniz Thanks for your comment!
Neat to see some familiar equipment on your bench. I worked for Transistor Devices, Inc. after they moved from Cedar Knolls, NJ to Hackettstown, NJ. I never worked in the Dynaload department but I used a bunch of different models over the three years I worked there to test other power supply equipment.
Great explanation of how a linear power supply operates, and how correct repair makes a difference vs. a jury-rig repair. Thanks for putting this video together.
Don Bower Glad you enjoyed the Video Don. Thanks for your comment!
Hello there Paul once again. I enjoyed watching you going through this video of the power supply repair and restoration. It 's a long while since I did a complete rebuild on a heavy duty "Lab Gear" power supply that I had purchased from a supplier in Leeds. I knew the psu was faulty when I got it, so had that in mind has to be a repair project. On my first inspection I knew that I was going to be doing a complete re-build. All of the components were like out of the ark. So a shopping list was made up and the new gear purchased. Lord knows what the transformer specs where but the size of it reminded me of a ark welder unit. Plus the gauge of the secondary wires to boot. The original stud diodes where 40 Amp devises. 1 was blown. OC. I asked at the place where I had got the PSU from for as near as poss replacement for it. He had a set of 50 Amp studs that were the same size, so I said I would take those to keep a matched set. I got them for free. I got a identical heat sink to mount 4 extra TO3 power transistors on making a total of 8. By the time I was finished working on it it had Variable voltage control, auto heat sensing for fan cooling and metering for current and voltage. It was something that I enjoyed doing and was proud of my work. By the way the transistors and the stud diodes got plenty of thermal paste Hi Hi.
See you later and carry on the good work. 73 de John - G0WXU.
Hey, I have one of those. Many years ago we had a local department store that was going out of busness and had a big sale and every thing was going, even the shelving. When I got there most all was gone however i found a car stereo desplay that already had all of the radios and speakers removed. I looked inside and found this large power supply. I asked the clerk what he would sell this desplay for. He looked at me like I had two heads and then said 15$. At the time I was into CB raido and knew that it would be great to power a moble radio and what ever "accessaries" I wanted to run. I got the thing home and took it apart and found the Astron RS-35A. I have used it for many years with no issues.
This is a very good illustration of the effectiveness of thermal paste and how important it is to use it. Those transistors were living on borrowed time.
It is always a pleasure to see your videos.
You are so thorough and comprehensive.
Thank you cope to show us!
Thanks Emil!
Very nice explanation of the power supply and the replacement of the thermoisolating stuff in order to cool down the temperature to the output transistor. Also the variable loads applied before and after the measurements . Thank you very much for your excellent demonstration. A.ballestri.suisse Switzerland
i have the variable version of the supply the VS-35m. The tweaky part of these supplies is the current limiting circuit. They don't just use the voltage across a ballast resistor to drive the lm723 current limit, they pick off a voltage upstream using that 300 ohm resistor which is a Vbe and a diode drop upstream which vary in value with the loading. Then they divide that down using resistors which that 300 ohm is part of. They also hand pick parallel resistors called Rx at time of manufacture for each unit depending on how it measures. The VS-35m is even worse in how it does this using a pot to inject voltage into that divider. A very touchy circuit. Nice job on the rebuild, I do wish you had exercised the current limiting to see if it performed as you thought it should.
I love all your information and helpful hints!
" Your how to " video's " AT Your Own Risk " of course are fantastic. Just wish that you showed more of the back side or inside of the PS , where the transistors plugged in by the heat sink. Great video's keep it going.
Thank you for this video! I have this same power supply and as old as it is, I'm going to order some Dow Corning 340 thermal compound, a few new TO-3 mica insulators and clean and re-grease the transistors just like you did. I'll just consider it preventative maintenance. Thanks again! BTW: I'm old enough to remember Allied Radio and Knight Kits: that's a blast from the past!
This is a phenomenal Channel. Your integrity and attention to detail is second to none. Your ability to articulate knowledge and move logically through a repair is resulting in some very low impedance learning. Thank you.
That was a cool way to put it! I’m 65 and been a ham for 45 years and I’m learning so much from Mr. C!
Bought my ASTRON RS-35A Power Supply in the late 80’s. This year I converted it to RS-35M by adding one of those volts amp module (50A) from Amazon. Looks good. Now should go back and check the pass transistors for thermal grease. This may give me 25 amps, as I was only getting about 20 amps before throttle down.
Thanks for the nice video. I own the same power supply so I learned several tips if it ever goes bad. I think the reason the pass transistors got warm so fast before is because 1) yes, lousy thermal coupling and 2) the other 3 transistors had to make up the difference for the "bad" one. Again thanks for to great videos. Between you and TRX bench I'm always learning something new. 73's
Mr. Carlson is my Mr. Wizard. Thanks for teaching us.
Good info here. I have a VS-50M that has run basically non-stop since 1985. Next time I clean the interior of it I will check the sockets and put on some new thermal compound. Thanks for your time and effort producing your videos. 73, WG2E.
This was a great post. I own the very same Astron power supply. It’s working fine at this point but it’s 18 years old and I’m sure the thermal transfer grease has to be dry. As a precaution, I’m going to remove the transistor’s and apply new grease. I truly appreciate the safety tips regarding the capacitor and the tip about keeping a ground jumper applied during service. Thanks and continue the good work!!!
The best video Channel on UA-cam. *****
Another great video. Just wish Mr. Carlson had more videos. Find his videos to be the best on youtube for really teaching the repair concepts in depth. Thanks a million.
Kevin
Kevin Gray Glad your enjoying the video's Kevin. Working on another right now. Thanks for the great comment!
Great instructional video. Great repair! Thanks for posting this! I look forward to more of your work. BTW, I have the Astron RS-35M...great supply. Again, thanks...stay safe!
your videos are so detailed and it's easy for noobs like me to understand very clearly
That Dynaload is a beast!
Thanks for making these repair videos.
Great Video
This guy is a geek man's man! Dude you are awesome! Thank you for posting these videos and educating us. You are an asset to humanity. Cheers!
Tony
Hey Mr. Carlson, do you have a part number or recommendation for the heat sink size you utilized on the pass transistor? I'm getting ready to make this upgrade to my Astron and I'm having a hell of a time finding the right heat sink. Thank you kindly, and as always thank you for what you do. 73 KN6BVX
Mr. Carlson; First visit, first video...compliments on unscripted, well spoken voiceover...informative, including background and safety info. Well equipped bench, and it looks like you know what to do with all that equipment! 25A through those pass transistor sockets on the Astron is a bit much for me...I realize it would make them a lot harder to check/replace, but I'd be tempted to solder Base and Emitter leads, so socket connections couldn't fail again...RELIABILITY is key...as is use of heat sink compound! '73 KA1RPB
man, I love your precise fixes! simply doing it as it should
Thanks!
I have an RS12 that I run my security cameras on. It's been running 24/7 for the past 12 years with no problems. I also have an RS20 I keep on my workbench. Both have been 100% reliable. I think they're great.
+Glenn Martin
Thanks for your comment Glenn!
@@MrCarlsonsLab I have to 70 n 1 50 n all of them are soft about 10v got all them in 95 the 70 from aes n the 50 at a ham fest
I run the 70 together
Just purchased an Astron RS12A power supply to power an Icom R-75 and a couple of miscellaneous radios. Now you've got me wanting to buy some thermal paste. Great video!
Steven Crawford Thanks for the comment Steven, Glad you enjoyed the video.
Thanks for this video. I am a pipe organ builder and use this power supply in all the organs. These supplies are very reliable and when they do fail it is usually what you found on this one.
Great video as always, nice to see someone who cares enough to do things correctly!
knunne1 Thanks! Glad your enjoying the video's!
I just purchased that power supply new - I want to modify the heat sink to your specs and "improve" on the original design. I think now my supply will last a lifetime because I know how to fix it from the transistors to the sensor - great job fun to watch video
Great video as usual sir. Thank You. I had an RS-50M years ago. When almost new i actually saw a line of smoke come out of it. I cannot remember details but, after seeing your video, remember the lack of proper heat sink compound on the either side mounted pass transistors. And i also had regulator board issues as this one and i noticed some significant poor factory soldering. After cleaning all that up, i tinned the filter cap board traces and added star washers. Those filter cap screws were really loose i remember. Keep in mind i bought this thing new! After all that i ran it for many years on WSJT at close to 200 watts and had other gear hooked to it with no issues.
plantopguy5 Great story! Thanks for the post.
Excellent video Mr. Carlson using those God given senses of touch are nice to have.
Thanks Dr.John!
You do such nice work. You make repairs a bit like art. Why just replace a transistor when you can find a beautiful new heat sink that fits like glove on to the old board. Beautiful job and great explanation.
Thanks you sir for the video. UA-cam is full of people making videos of things they have knowledge about. You are an expert and I appreciate your sharing your skills.
+Ian Butler Sorry, I meant they have no knowledge
+Ian Butler
Thanks for your kind words Ian!
You are a great teacher and a genius. Thanks from Boston! 73 KC1ANR
Good repair job on the power supply and a good thing it incorporates a crowbar
circuit for protection of devices. You reminded me on checking my 60 amp
TrippLite power supply, Thanks.
Dennis Petersen Thanks for the comment! Many people praise the crowbar.
Hi Mr Carson, I finally got some time to check out the Tatung power supply. found the problem, it was a 5000 uf 100 v capacitor. All is well now. Thanks,Arnold.
I 've been following many of your video,s and they are all well done. You obviously are an engineer or a very good technician. Building circuits for correcting problems impress me a lot. 73 de VE2WNF
Glad your enjoying the video's Andre.
I just found this video and it is very interesting. I have 2 Astron RS-20A supplies. One has been running almost continuously since 1988. The other is about 8 years old. The old one has run flawlessly, the newer one has had an intermittent since almost day one. However, it does not go out often enough to motivate me to really dig into it. If I turn it on and it supplies voltage it is fine until turned off. But if it is going to act up it will have zero volts on turn on until I flip it on and off and it behaves. One of these days it will annoy me enough to see what is going on. Thanks for this video!
I've got a supply like this. I've "ruined" the antique value by putting some Radio Shack meters in there with modified numbers on the current meter. I've used a voltage meter for both. I also drilled two holes in each meter and installed two white leds. Looks nice. This is the perfect supply for any 100 watt 12 volt radio! 20 amps "continuous" I would like another video describing the ic circuits more, especially why they use a 5 volt circuit for sensing over- voltage and how the error amplifier works. Great video! Thanks!
Another very good video, one thing that was not discussed was the merit of not dropping too much voltage across the pass transistors.
Many people feel inclined to put bigger smoothing capacitors in powersupplies like this, as long as the troughs of the ripple are higher than the dropout voltage of the regulator the capacitor is big enough.
Bigger capacitors reduce the conduction angle of the rectifiers and stress the transformer more causing more temperature rise, the pass transistors and heatsink will also get hotter.
Once again a very good video with good advice!
David Lisney Thanks for your comment David!
Enjoyed the video. Over the years, I have had several of these Astron power supplies. They do a good job. They seem to be somewhat sensitive to RF getting in and blowing out the 723. A little RF bypassing will take care of this in most cases. 73
W5KCM Thanks for the comment!
Hello, Mr Carlson, Thank you very much for the reply. I have checked the transistor and it is ok but haven't had time to do more testing now. I am so busy I am meeting myself coming and going. I will let you know what I find when I find it Lol. Have a great day. Thanks, again. Arnold.
Learned a bit about a similar Astron power supply. Thanks
love your video's...trying to catch up on all of them...Thanks for being on UA-cam...
+David Davidson
Your welcome David. Glad your enjoying.
quality person with some integrity for others people's equipment
Well, I thought i was good with repair, But you show how to go the extra mile to make sure a PS repair will last at least as long as the caps or the weakest link. you are making me improve my amateur skills , also love the weller soldering gun re wire. Duh Ive always hated the way the switch worked and never thought to re wire it- no brainer , just do it and you get the best tools in the world that work for you.
Wow! What a great lesson again! Thank you!
Awesome video, I could follow along all the way this time, no homework!
Nick Moore Thanks for the comment Nick. Looking forward to that motor :^)
Just amazing videos. I am in awe of what you do.
Very nice repair on the Astron. I have two Astron supplies. They weigh a few pounds but being linear are very quiet (RF quiet).
***** I agree, nice quiet linear supplies are the way to go, at least around radio gear. Thanks for the comment!
Hi..I use to have one of these power supplies..but with the meters...a very nice supply...weighted a ton..and never failed me...