Astron RS-20M 20 Amp - 13.8 Volt Power Supply Repair - Shuts down - Overvoltage Issue

[@SpeakerFreak95]

Seeing all that flux getting cleaned off that board was oddly satisfying.

[@frankpitochelli6786]

Steve, you're a genius. Always enjoy the videos and the troubleshooting. 👍💯

[@ggsumner1947]

I purchased a lot of Astron power supplies for towboat use on radios, and digital marine radar use. They were the best for the money, but power on towboats would blow the SCR and power transistors out. We would do an exchange at a reduced price so the boat could proceed on the river. We also used them for land based Motorola installations as well. Most failures in our case was the SCR, so I bought higher current ones to keep failures down, and customers happy. Your modifications are very interesting.

[@dpyles9396]

I have 578 KZbin subscription and yours are in my top 3 I always look for! Thanks for the great work!!!

[@montygore]

I enjoyed your video as usual. I like the way you clean your boards

[@Michael-xl8dz]

Thank you for all of the vary detail information now if I could only have my own fixed .. 😅

[@Dark_Knight_USA]

Greetings: Indeed they had problems with the 723 design reliability. Usually voltage backfeed on the 723 output. This normally occurred if the pass Txtrs shorted collector/base and shorted the TIP-29. Most of these units were used in communications. As such over current, extended high current and RF taking out the pass Txtrs. I have resigned the regulator and pass circuit preventing such. The 6055s is a new application 2 me. These units came with 3055s up to the early 20A units. Later 20As and above had 3771s, (higher current devices). The TO-220 U said as a TIP-28 should B a TIP-29 according 2 schematic, Mfr use and my experience. I am glad U figured out the back voltage problem and Mod. The Full bridge is a good idea on the 15A and lower units. I do not recommend the standard 25A block full-wave bridge units on 20A and above units. FYI: I have been repairing these since their onset in the 80s. I do not recommend charging a battery with these units. The pass Txtrs do not like the load resistance if not corrected... Another Mod I applied. I applaud Ur stripping and proper reapplication of heatsink grease. Most do not clean, reapply and if they do apply it is way 2 much. Good job.

[@TheDefpom]

So that’s why I purchased those LM723, spares for my VS-35M… I couldn’t remember why I got them!

[@tubeDude48]

Excellent, as always!

[@AverageRetiredGeek]

Very nice - would have liked to have seen some testing with a load!

[@barryg41]

I use three different super lube products. 👍 You really missed your chance on a booming ELECTRABOOM "FULL BRIDGE RECTOFIER" Good stuff! 🙌

[@zari63]

Nice repair norcal

[@hemi5463]

Yknow, for transistors dated 1986, they were built pretty solid to last as long as they did

[@jimborambo958]

Thanks for sharing the video! May I know what’s the desoldering pump you used?

[@norcal715]

It is a Hakko FR-301 desoldering pump. Thanks for asking.

[@zari63]

Analog dc ps great classic machine

[@tinkeringwithelectronics]

Thanks for the time you took putting this together. What do you use to clean the boards??

[@norcal715]

Acetone and a acid brush.

[@tinkeringwithelectronics]

@@norcal715 thanks, it sure looks great

[@rad2304]

Hello there and thanks very much for all your helpful videos! I have an Astron VLS- 25M and whenever I key up a 20W mobile UHF radio it shuts down. I checked the LM723 pin voltages and all looks normal except for pins 4 and 5 has 3.067V instead of 7V and pins 11 & 12 at 41.19 V instead of 29.0 V. Any idea what’s causing it? Thanks very much in advance!

[@norcal715]

Try it with another load of the same or more current. It could be the RF from the transmitter shutting it down.

[@truckingfun5033]

Did you ever find out what was the cause of your power supply to shut down when transmitting? I’ve got an Astron 50m doing the same exact thing when I key up a 100 watt hf transceiver. Everything is fine until I try to draw around 12 to 15 amps from power supply, and then it drops amperage and voltage….

[@rayfalcone6897]

genius

[@DanTurner266]

I have a RS-20M that only puts out 12.04VDC on the output terminals tested with a Fluke MM. Should this be 13.8VDC? Can I adjust this closer to 13.8VDC?

[@norcal715]

There is an adjustment potentiometer on the board, and unless there is another issue, you should be able to adjust it past 13.8 volts.

[@DanTurner266]

@@norcal715 Thanks, I found it, set it right at 13.80VDC

[@williamchow1624]

Is the design of the power supply flawed where you had to modify it?

[@SeanBZA]

Not really, just things the original designer lefty out as not too critical, or modifications to suit a purpose somewhat different than the original designer intended.

[@CoquiAudio]

hi, the diode modification is only for that model Astron RS-20M 20 Amps only?

[@norcal715]

The same mod is done to my RS-35M also

[@CoquiAudio]

@@norcal715 thank you, I redraw the PCB and going to add it

[@CoquiAudio]

@@norcal715 sorry to ask again, the diode is a 1N4004?

[@dipakbhalodia7155]

How to download site veariyesh circuit diagram please my give me site

[@abeleski]

1st

[@norcal715]

Ya im not that big of a youtube creator. I do appreciate it though!