[Premium-Rx] Cubic R-3030/80 Power Supply

[Glenn Little WB4UIV]

Replace all the electrolytics.
The gunky stuff may be a glue as the MIL-Spec requires it on parts above 
a certain mass.

73
Glenn
WB4UIV

On 6/16/2020 9:47 AM, Todd K. Rodgers wrote:
> Hello group
>
> I've got a Cubic R-3080 (half width) receiver. It's been working fine 
> for 10 years now. On the last power up attempt, nothing. Removing 
> covers, the power supply has faulted. I warm up the soldering iron, 
> pull out the VOM and know to look for bad electrolytics, blown 
> thermistors, etc. I pull out the manual, start comparing the power 
> supply schematic to what I have and it just doesn't look the same.
>
> I then notice that the power supply part number on the exterior of the 
> module is ASSY NO. 2871-1104, then that the diagonal stripe on the 
> module top face actually "slopes" in the opposite direction from all 
> other modules (no straight "line" here) and isn't in the last module, 
> right most (viewing from front of chassis, top side) position. Opening 
> up the power supply module (not ever done before) reveals some 
> evidence of modification, and some gunky stuff around the large filter 
> caps (perhaps original glue to affix the device better to the board, 
> perhaps leakage). The internal board layout doesn't match any of the 
> drawings/schematics I've been able to get my hands on.
>
> Anyway, the repair operation can take two routes:
>
>  * Trace out everything, make sense of this "new" circuit", and
>    judiciously replace parts and restore this odd power supply to
>    working order
>  * Or, attempt to replace all innards with modern switching power
>    supplies for +-16VDC and 8VDC (either mounted in the original power
>    supply casing or externally). I'm guessing heat generation might be
>    an issue (so perhaps best to avoid linear supplies) so don't want to
>    go overboard.
>
> The second option begs the question what current level outputs are 
> required for the 3 voltages? Does anyone on the list have any ideas?
>
> Any thoughts/suggestions, most appreciated. Any source of original and 
> appropriate power supply modules (ASSY NO. 2140-1124) also of interest.
>
> thanks!
>
> Todd, KC1SQ
>
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-- 
-----------------------------------------------------------------------
Glenn Little                ARRL Technical Specialist   QCWA  LM 28417
Amateur Callsign:  WB4UIV            wb4uiv at arrl.net    AMSAT LM 2178
QTH:  Goose Creek, SC USA (EM92xx)  USSVI LM   NRA LM   SBE ARRL TAPR
"It is not the class of license that the Amateur holds but the class
of the Amateur that holds the license"