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Author Topic: C&A Electronics KIT CA115 DC 0-25V / 0-3,5A LM723CH PSU Remake  (Read 1703 times)

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Online Kiriakos GR

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This is my first ever adjustable PSU with voltage adjustment along current limiter.
C&A Electronics in Greece was one of the first sources at 1987 at the offering of electronic kit.
CA115 KIT this is DC 0-25V / 0-3,5A power supply, and main IC this is LM723CH with 10 pin.

While back at the year 1987 this LM723CH with TO-100 package it might was popular, at 2024 it’s not.
At my personal stock of IC I do have a pair of Motorola MC1723CP genuine old stock of 90s.

My PSU yesterday this had a sudden damage when I was using it as battery charger, and now I am a bit lost, because I have to return and repair a 37 years old PSU design.
I did kept in good storage CA 115 four pages of electronic circuit and printed in Greek language of assembly and troubleshooting instructions.

C&A Electronics KIT CA115 this is extremely unique, it requires two AC transformers, separate PSU for the LM723 along a separate PSU for the output stage.

I thought to research Google search finds about this schematic and I found nothing. 
But I did found lots of useless scammers from India, them to have steal and reproduce all short of LM323 schematics but they do not have this one.

Under lots of thought I did decide to hide and protect the electronics design knowledge of this specific PSU.
Instead I will only present some work of my own for the pin out conversion from the unpopular LM723CH package to the more popular LM723 14 pin socket.

I am now preparing myself for going a bit of DIY.
I will use an new 14 pin PCB IC socket, and will add soldered wires as leads, and then I will solder these at the PCB this originally designed to accept a 10 leads IC.         
 
I am also planning to do some extra work at this KIT PCB, a bit of cleaning, restoration replacement of old wires  with new.
Fresh soldering and removal of ancient over PCB soldered pins these originally placed as on-top soldering points.

So I am going to give it a complete remake after of 37 years (first assembly), now that I have huge amount of expertise along tooling pack and all sort of spare parts.
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Offline Andrew-88

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Re: C&A Electronics KIT CA115 DC 0-25V / 0-3,5A LM723CH PSU Remake
« Reply #1 on: May 05, 2024, 01:03:18 PM »
Not all C&A Electronics Kit were designed with excellence but I do not recall Smart-Kit brand this having a close equivalent of PSU with current limiter.

Unfortunately, C&A Electronics in Greece, this ended it operation end of 2012.
And nothing saved speaking of product details and KIT schematics.

About KIT CA115, you do have unique content in your hands, KIT along complete documentation.
As far I am remembering, KIT documentation this was released as photocopy of text written in typewriter.  :)   

Online Kiriakos GR

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Re: C&A Electronics KIT CA115 DC 0-25V / 0-3,5A LM723CH PSU Remake
« Reply #2 on: May 06, 2024, 08:34:57 PM »
As far I am remembering, KIT documentation this was released as photocopy of text written in typewriter.  :)   

This is a fact.
Text written in typewriter and this photocopied hundreds of times, this was and is an tremendously hard to read documentation.
Even so I am now thankful to my self, because I do keep safely stored anything from my youth up to nowadays, regarding electronic schematics and instructions.
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Online Kiriakos GR

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Re: C&A Electronics KIT CA115 DC 0-25V / 0-3,5A LM723CH PSU Remake
« Reply #3 on: May 15, 2024, 08:00:09 PM »
Remake successful  :) 

I am happy again, my first ever DC PSU  KIT assembled by me in my youth, this is back in action.
But now I noticed small annoying issues, its in the nature of LM723 to be sensitive to noise, and special capacitors exist at the schematic.
But now that I am not using any more the full metal TO-100 package, the plastic LM723 this is further sensitive.

And so while my PSU this is functional again, voltage output this is not that stable.
There is slightly oscillation noise, and I have now to take it apart again, so to add few filtering capacitors so to further improve it.   
 
Here is a pack of photographs of my project.   
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