[Elecraft] OT: Astron linear PS regulation issues

[Randy Farmer]

I have two recent vintage Astron RS-35M units. They still use the exact 
same 723-based regulator circuit that they have used for thirty years or 
more, so the design hasn't changed. What **may** have changed is the 
build quality. I carefully inspected both of mine right after taking 
delivery. I made sure the green wire from the AC cord was securely 
bonded to the chassis and checked for obvious soldering problems. I also 
tied the negative output line to the chassis. They have both been 
running like trains 24-7 for the last three years or so. The only 
failures I've had (on both units) are the stupid internal meter lamps.

73...
Randy, W8FN

On 2/25/2019 8:36 PM, Kevin McQuiggin (SFU) wrote:
> I have a ~30-year old Astron 13.8 VDC 20-amp supply that I got when it was retired from a project at work.  I used it for low current applications for a few years, then it went to storage for about 5 years.
>
> One of the two power transistors failed a few months ago and this took out some other components.  I had put it back into service in a 5-10 amp application.  I figure that the failure was likely just due to age and the fact that the supply had been in storage for a few years.
>
> I replaced both of the power transistors, two blown diodes, the electrolytics, and a couple of ICs and other components, and the supply is running fine again.  Solid output at 10 amps load.
>
> Given its age I am extremely happy with it.  The internal quality and components seemed good, but that may have been due to its design/manufacturing era.   Not to sound like some old codger, but perhaps designs aren’t as robust as they used to be.
>
> Kevin, VE7ZD