[Boatanchors] 'Stoopid' OT question

[Phil]

Thank you,

I don't go to the repeater remote sites, I let others do that. I'm not 
sure what this one was actually powering, most of our sites use Astron 
50A supplies.  I've overhauled some of those 50A supplies, and in fact 
was given one for myself, which I use as a backup supply to the MFJ 
switcher that keeps my batteries charged (3 120AH/Hr batteries in 
parallel) as well as running the radio gear.  A 300Amp "boat" battery 
changeover switch selects which power supply  is in use (when I run on 
battery during power outages or field day, class 1E I use the 50A unit 
to bring the batteries back up).  The batteries are on line 24/7 and in 
the almost 18 years this system has been in use I've never had a power 
glitch or PS related problem in any of my radio gear (keeping fingers 
crossed).  Some of the radios are on 24/7

Anyway, I'll do some research and then advise our repeater guru that it 
probably wouldn't be a good idea to put this SEC-1223 at any remote 
locations.  I'll go ahead and repair it and suggest that they only use 
it for "light load, easy access" sites like the remote receivers in 
Fresno, Turlock etc.

73 From "The Beaconeer's Lair"
Specializing in DXing NDBs (Longwave Beacons)
Phil, KO6BB,  http://www.qsl.net/ko6bb/
KO6BB/B beacon, ~20W on 28.290 MHz, Ringo Vertical

HF/LF RADIOS:
HOMEBREW:   7 Tube+Rect 1v3 Regen RX for LF (built 2015)
Icom:       IC-7200 Xceiver, DSP IF & filters (~2015).
Kenwood:    TS-450SAT Xceiver, cascaded 250/125Hz Inrad filters.
10M Beacon: 2 x Realistic HTX-100's on 28.290MHz
SDR:        Softrock Ensemble II LF (built from a kit 2017).

ACC:   HOMEBREW  LF-MF Pre-Amp, 8Hz Audio Filter.
        HOMEBREW  4 Port Antenna Multicoupler, Feeds 4 RX's.
        
ANTENNAS: 88 foot Long Ladder-line fed dipole, 35 feet AGL for MW/SW.
           Active Mini-Whip, 36 Feet AGL for LF/MW/SW.
           37 foot "Low Noise Vertical", 11 feet AGL for LF/MW/SW.
           Cushcraft AR-10 Ringo Vertical, 14 feet AGL for 10M beacon.
Merced, Central California, 37, 18, 37N   120, 30, 6W CM97rh

On 8/12/2017 3:10 AM, Chuck McGregor wrote:
> Phil-
> Suggest an ebay search on your power supply number.... if it is Samlex 
> SEC 1223, there are parts kits available, and also prices on a 
> replacement supply which you might want to compare.  See ebay item:  
> 142415928057
>
> Availability of a repair parts kit suggests this may be a frequent 
> failure.....You might want to compare with alternative makers.
> 73
> Chuck K7MCG
>
>
> On Fri, Aug 11, 2017 at 7:30 PM, Phil <ko6bb1 at gmail.com 
> <mailto:ko6bb1 at gmail.com>> wrote:
>
>     Hi,
>
>     Right now I have a Samlex SC1223 12V switching PS on the bench. 
>     It was used on one of the remotes for the club W6BXN repeater
>     system.  Anywhoo, it failed, blowing he primary fuse.  Samlex was
>     nice enough to send me a .PDF file of the schematic.  Found the
>     output switching transistors (2SC3320) are both shorted.  No
>     problem, they're readily available at reasonable cost.  Over the
>     past 60+ years I've repaired a gazillion power supplies, but not a
>     lot of experience with the switchers, hence the question.
>
>     This unit has three 2200uF 25V Caps for filtering of the 12 Volt
>     line.  Two in parallel right after the rectifier and a third after
>     some filter chokes.  The two parallel units are "bulging" at the
>     top, it appears that luck was with us and they didn't blow their
>     guts all over the inside of the unit.
>
>     My plans call to replace them along with the transistors, I'm just
>     not sure of one thing.  In a switching supply (runs at 25kHz), do
>     I need to order some special "Low ESR" 'lytics, or will everyday
>     run of the mill 2200uF 25Volt 'lytics do just fine???
>


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