I read somewhere that a humming Astron is a sign of a dying rectifier. When it fails dead short like that, it's going to dump AC on your brand new filter cap, which probably killed it too. Glad you finally got it all figured out.

@k2cjbradio

Жыл бұрын

Thanks! And it’s still working a few months later. Looks like I bought a little more time with the repair.

My astron crashed on me...started with the hum...once I open it up it was the bridge rectifiers. Called astron and they used a bad batch...sent me new ones for both of my supplies free...great customer service..

@k2cjbradio

Жыл бұрын

Yes they have great customer support and a great product!

Many of the individual components including ICs, power transistors, bridge rectifiers, capacitors, pots, and sometimes even transformers and printed circuit boards will have Electronic Components Industry Association date codes in the format YYWW. For example the 9425 number seen on C5 at 5:24 could translate to the June 20-26, 1994. The 9502 code seen on the bridge at 10:33 translates to the second week containing a Thursday of January 1995. The more date codes you can find on original parts, the closer you can estimate the age of the equipment. In some cases even the serial number of the assembled product has an embedded date code.

This has been very helpful. You give a great, cut-to-the-chase video presentation. I have an older RS-35M with the single meter that I bought at a hamfest. The OM seemed a bit senile & he told me he tried to fix it himself. It has an additional C5 capacitor in it for some reason. But the PSU was only $20 so I now it's my headache. I have decided to fix all of my bad PSUs & this one is my bigger challenge.

@k2cjbradio

Жыл бұрын

Sounds like you got a pretty good deal if you can get it working!

Chris, Good to see you back on the air. Looking forward to seeing you out and about in the Connecticut area playing POTA. 73 George KB3WAQ

Morning Chris! The trick to putting those sheet metal covers on is to put all screws in loose so you can shift the cover around to line the holes up. When all screws have been started, tighten them down.

@k2cjbradio

3 жыл бұрын

Yeah it was definitely a little wrestling match to get the cover on and off. Same with mounting the rectifiers. But, I’m glad it’s working now.

@a2phil

11 ай бұрын

Things always seem to warp somewhat over the years...

I bought a used one fifteen years ago! Every once in a while It would hum and the output Voltage was oscillating wildly. I checked the rectifiers. Always ok! I finally checked the control board. One of the solder joints On the board didn't look right. I sucked off the solder, then I checked the components. They were ok but the leads on The components didn't look clean enough. I scrapped the leads with a Sharp knife to make them shiny I resoldered the leads to the board. No more oscillation For the last ten years

Glad you got it fixed! Great video, thanks for sharing this

@k2cjbradio

3 жыл бұрын

Thanks! Hopefully I get another 20-plus years out of it!

While it’s all apart- remove the transistors, clean everything up and buy new Mica insulators and put new white heat sink compound on all 4 transistors. They should be cool to the touch when operating. I purchased my Astron 35, 21 years ago. I just replaced the voltage board, the big filter capacitor and the transistors and mica insulators. Works great again. It will probably outlive me.

@a2phil

11 ай бұрын

Just bought one at a garage sale for $50, guy said transistors got hot, took them off, still good, new insulators with heat sink compound, and works fine now!!! Going by the serial number it's 30 years old!!!

The Lm723 is also found in Manson power supplies. I have had a few to repair over the years, shorted rectifier and sometimes dead pass transistors on the heatsink. But they are so easy to repair, so i put up with the faults :-D

@k2cjbradio

Жыл бұрын

Exactly!

OMG, just got that joke at the start, hmmmmmm, when you pointed out the two terminals on that large capacitor it looked like you almost touched them and I jumped, haha. I replaced the same part (bridge rectifier) on my RS-20A but I called Astron and asked for their tech support/re because the varistor and the transformer appeared to be function well, and their support said the bridge rectifier is typically the culprit. Your videos are fun to watch, I like how you cut to the close ups. Well done!

@k2cjbradio

Жыл бұрын

Thanks for watching and the kind words…and for getting the joke!! My Astron is holding up with no problems. Great power supply.

Nice work. Seems like old capacitors are the last failure point. Boards on model trains (MTH) had a series made with crap capacitors from China that were a common failure. New air conditioners seem to have the same issue. Hmmm. Nice job on the fix.

Thanks for the effort, most helpful. I have a Vs-50 that's buzzing crazy.

One of my GE Mastr 2 power supplies used to hum @ 60Hz while idle and really get down when under load but it was the main transformer just showing it's age. I wound up replacing the original transformer with a toroidal type with a higher amp rating (somewhere around 100 amps or so since I rewound it with heavier gauge wire) and dual tapped for 15 and 5 volts, new FBR, inrush limiter and filters. Also replace the front plate fuses with breakers, added cooling fans and a digital volt / amp meter. The filters and regulation for the 12 volt side in this one was fine so no need to change it. I did fabricate the 5 volt regulation and filtering though. The second GE unit I completely gutted out and installed a pair of 12 volt / 40 amp SMPU's in parallel to raise the output current to 80 amps, added in some extra filtering (because SMPU's tend to make noise on RF) and some fans. Front panel got a makeover with a new AC mains socket, breakers and indicators and a digital volt / amp meter, finally both units got a coat of metal primer, black paint and then a light semi gloss coat. New decals and GE logos addes then sealed up with a final coat of gloss I have a third GE PSU that is all original but it too needs a makeover because it has a hum and also has bad filter caps. Lots of hours on it from it's former life in a UHF Commercial community repeater cabinet for the better part of IDK 40 years before it was finally taken out of service due to FCC narrowbanding requirements.., I like these power supplied though because they very usable as a DC power supply and have the AC mains socket on the front, they are serviceable for the most part, chunky with weight (all metal) and they are 19" rack mountable. Oh and they are "hackable" so if you want ditch t he heavy iron core transformers and big filters you can and drop in a fairly reliable SMPU module and a way smaller filter bank to clean off the switching noise.. That cap in your PSU is not a bulk cap so it is not a high voltage cap just a high farad value the 12 violt in it is not enough to break your bodys resistance to do any harm. Now if that were a SMPU then YES it could have anywhere from 250 - 480 volts DC on it and will let you know how it feels about you touching it if you touch it. You probably know this but discharging a cap, especially a big cap of high voltage or high capacity rating like you did is not good for the cap and the older the cap the more chance it will have to totally fail (usually short inside the cap or short one side of the FBR) when you discharge like that. Use a power resistor instead, something in the nature of the 2 plus watt area or just leave the equipment connected and powered on to drain the filter(s). Those big caps also can "recharge" over time so you may want to leave the resistor on the terminals, especially if you are in a SMPU across the bulk cap. For proper texting of caps you need a dedicated capacitor tester so you can properly test for leakage, value and ESR.. Multimeters can do it but they are not that accurate since they cannot put a caps working voltage on the cap under test

@k2cjbradio

2 жыл бұрын

Thanks for all of this!! Sounds like you had some fun working on a few supplies. Yeah, I know discharging the way I did wasn’t the best. I should have grabbed a higher power resistor to drain it. I was impatient and wanted to get the supply working. So far so good. Still no hum. Not bad for a really old power supply!

Well done

@k2cjbradio

8 ай бұрын

Thanks! Still working too!

Another good video. You bring us along nicely as you explain the troubleshooting steps. Excellent. Thanks for the video.

I Replaced my Two 2504 with Four 5001 all Tied together in my RS-35A Works Great I used the 5001 for that's what I had Laying around or I would have used 2504 if I didn't have anything Laying around and the 5001 there Chinese and with My Test there only Good for 15 amps at 100 Volts Not 50 Amps at 100 Volts as they Say but I Got 10 of them for $3.50 with Free Shipping so with Four They Should be Good too 60 Amps and 100 Volts witch in the RS-35A They will Never See anything more then at Best only 40 - 41 Amps at 24 - 30 Volts before it Downs it too 13.8 Volts and it Puts out all of the 40 Amps over the 35 amps it is Rated for.

I understand the new switch-modes are great but for radio I still think a linear is the go. The 'ol Astron lives another few decades. Given that electrolytic is that old I'd still replace it.

@k2cjbradio

3 жыл бұрын

Yeah, I might just do that..

@Elfnetdesigns

2 жыл бұрын

Depending on the brand of SMPU and what RF band you use with it will determine if you have a quiet PSU. SMPU noise pretty much goes away above 450MHz However, those cheap Chinesium infused one on ebay create a LOT of trash on RF and the switching transistors / MOSFETS are typically way under rated for the claimed PSU's output current rating. IE: A 40 amp may have a pair of 8 amp transistors of the cheapest Chinese stank quality available and will not last long under load. If you do buy one of those cheap bricks, before you connect power to it, open it and see what transistors / FETs are in it and replace them with better quality ones that are compatible and of higher current rating. Also while you are in there change out the main bulk capacitor, the stock ones are GARBAGE and will fail prematurely. As for cleaning up the RF noise you can shield the PSU more and add external filtering but in HF there will be noise. Linear PSU is the best but sometimes you may not have the room for a big heavy PSU.

Date code on the original filter capacitor is 1994.

test light works best to discharge the cap. its easier on it as well. 73 w7wza

Thanks 👍🇬🇧

why did you not use a single 50 am diode rectifier the problem with the way astron does them is equalizing?

@k2cjbradio

2 жыл бұрын

I used the Astron replacement part for the repair. Figured the first one lasted many years.

WD4OBP I had the same problem. The tech suggested replacing them with the 50 amp diodes. Mine failed at 6 months probably from gunning ft8 wide open.

@k2cjbradio

2 жыл бұрын

So far so good for me. And it’s been on 24/7. I think if it dies again I might spring for a new one!

My RS-35 took a lightning strike a few years ago and is blowing the fuse immediately on power on. I think I need to get inside it and see if I can get it back up. Thanks! Great video. AE5DW.

@k2cjbradio

2 жыл бұрын

Ouch! Good luck! It’s not a terribly complex power supply to troubleshoot and there are tons of schematics online for it.

@daleburrell6273

2 жыл бұрын

...sounds like a shorted rectifier-!

Thanks for this vid. I have this exact power supply which I got from my friend Jon's widow when he passed away. I never looked inside the thing yet because I didn't have the time to dig into it and figure out what is going on in there. From watching your vid it really looks like this thing is a real gutless wonder. Mine doesn't make the noise yours was making and it works for when my rig is in receive mode but when I transmit it shuts down. It would sure explain why he had a different supply in line to run his rigs and wasn't using this one - he probably switched it out when it started doing this. I'm thinking its probably something on the regulator board. I'd be interested in hearing your thoughts on this.

@k2cjbradio

8 ай бұрын

You’re right in that there isn’t a whole lot to it. My guess is the regulator may be the problem on your supply. The schematic is available online if you poke around. And parts are available from Astron. Mine is still working fine and I leave it on 24/7 under the desk. It really is a great power supply. Thanks and good luck!

John Boy Utah , these are great power supplies they use to sell them in the Ely Whitney catalogue years ago. I hate the switching PS junk being pushed on hams today! They don’t last and their fans are noisy! Hums because it doesn’t know the words! We had that problem at Grumman years ago it was blowing fuses. Turned out to be a Homotron a queer electron that blows fuses.

my rectifier quit too but I replaced it with one 50 amp instead of two small ones.

@k2cjbradio

2 жыл бұрын

Not a bad idea!

I have both an (old) 35 amp and a 20 amp supply. Both are on the shelf needing work. Repairing these things is expense compared to buying a new "switching" power supply--especiallyif you need a new transformer! But I think they are worth taking the time and trouble. I may be old school but when I read the RFI suppression specs on switching supplies my reaction is "yeah... OK." Also, what is the effect of leaving a switching supply "ON" continuously? Great video. Ditto on the cautions. Even at 13 volts, that supply can deliver enough current to literally start a fire.

@k2cjbradio

Жыл бұрын

Yeah, I am also skeptical of switching supplies. I know many ops use them but nothing beats a brute force power supply. If the transformer had failed I probably would’ve tossed the supply since it is pretty old. But, I think I might’ve bought a few more years of service with this repair. It’s still working and is on 24/7. Thanks for watching!

@247SH

Жыл бұрын

Interesting. I built the Marchwood 30amp PSU, G4JET’s design from the 1980s. It was the first thing I built with help from my uncle now silent key, so it’s a keeper. All the parts were sourced second-hand from radio junk sales, but it’s never let me down. I use it to power my Icom IC-756Pro. I’ve been using FT8 recently and getting ground loops into my computer taking the Internet connection out. Your video made me think the 2 33000 MFD 40v capacitors might be failing so I’ve ordered a pair. Many thanks, Alan

Why did you think the original cap was bad? You measured the ripple voltage as practically nothing. That cap is what filters the ripple. If it was failing you'd have ripple. While safety is certainly important, the secondary side of the supply is only 25V or so. It isn't going to hurt you as long as you don't go sticking metal rings or wrist watches into it to short things out - regardless of the current. And the secondary filter cap doesn't have enough voltage on it to bite you for the same reason. The primary is of course 120V and can bite you.

@k2cjbradio

Жыл бұрын

Yeah, I was just assuming the cap failed due to age.

You may not know that Astron chargers about $35-50 bucks to repair 35 and 50 amp power supplies

@stargazer7644

Жыл бұрын

And what does UPS charge to ship one?

@a2phil

11 ай бұрын

Another $50 shipped from Florida to Michigan when I got mine last month, took 4 days...

You're lucky your power supply was only humming. I was using my Astron while working FT8, and during one transmission cycle, the power supply made a loud 'clunk' sound and died.

@k2cjbradio

Жыл бұрын

Could be a good project…

DId you happen to test the new cap before you installed it?

@k2cjbradio

3 жыл бұрын

No I didn’t. Just assumed it was good before installing it.

Out of curiosity did you check both of the original bridges once you had them unsoldered? When wired in parallel for current, it is possible only one shorted giving you a possible good one to keep for emergency (temporary) use if needed..

@k2cjbradio

2 жыл бұрын

Not yet but you are right if one tests good. I was thrilled to see the supply working again!

@Elfnetdesigns

2 жыл бұрын

It is BEST to change them both regardless. Aside from the main filter I would have checked the caps in the regulating circuit as well

Its my belief that those rectifiers in tandum only one does most of the work so I replace them with one 50 amp

@k2cjbradio

10 ай бұрын

You’re probably right. I just figured I would replace what was there and hope I get another 20 or so years. Thanks for watching!

Have a dead RS-35A, I will look at repairing it.

@k2cjbradio

Жыл бұрын

Luckily it’s a relatively straightforward circuit. Just be careful of those capacitors. They do hold a charge!

@jameski5oeb668

Жыл бұрын

@@k2cjbradio I will discharge it first.

Is it normal to make a little hum when powered on? I just got a new one today. Just that little slight steady hum that sounds like when you power on something big. Mine is the RS-70A.

@k2cjbradio

Жыл бұрын

I would think so because of the large transformer.

@chasiu75

Жыл бұрын

@@k2cjbradio Thank you for responding, it did sound like something I heard before from devices with large transformers.

@stargazer7644

Жыл бұрын

@@chasiu75 You're hearing magnetostriction in the laminations. It is normal.

Enjoyed the video ks4ww

Very impressive 👏 I wish I could Learn electronics

@WI9LL

3 жыл бұрын

You can!

I see you have a Tempo One in the background, do you have any videos for that power supply?? Thanks KE8NFK

@k2cjbradio

11 ай бұрын

Not yet but I do plan to replace the capacitors and power cord!

@a2phil

11 ай бұрын

@@k2cjbradio Cool!! I replaced the filter capacitors with 2 section ones ( couldn't find any 3 section ones) and put in an "extra " axial capacitor, but not sure if I wired it in the right way, schematics are Greek to me!!

0:23...because it doesn't know the WORDS(?)

my power supply is making noise... hmm

First to say First

First to say First kk6ikw

That is a dumb design; Astron really dropped the ball on the RS-35. Those bridge rectifiers are rated at 200 volts (good) and 25 amps (bad). You have two bridge rectifiers put in parallel, which is moronic at best; when you have two rectifiers in parallel one rectifier will almost always conduct sooner (at a lower voltage) than the other, which means one will take most of the loading. They should have just used one bridge rectifier rated at 40 or 50 amps.

Why do people allow their power supplies to go on when the worse is yet to come. Never fails people should know better..

why did you not separate the 2 rectifiers and test,also why did you not test the cap for capacitance shorts+esr before assuming its dead,looks like you need to keep your day job! quite a fail realy.

Liked and subscribed De KD5INM

@k2cjbradio

3 ай бұрын

Thanks!