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The Renard SS-16 Christmas Light Controller board comes equipped with an on board 5V supply.  Having several high current 5V supplies on hand, I decided to use them, sparing the expense of the transformers, regulators, caps, diodes, etc.

Mostly Complete Renard SS-16

Shown above is a mostly complete Renard SS-16, sixteen channel christmas light controller.  J1 & J2 and the PICs were backordered and added later.  Below are the steps necessary to add an external power supply without cutting traces.  The board can later be restored to its original functionality.

• Do not populate C1, C2, D1 – D4, TF1 and U1.
• R1, R2 and U2 are not populated in this example as I wished to use a ZC (zero crossing) signal generated externally and sent over the CAT-5 cable.  ((See below for on-board generated ZC)).
• Install a jumper between the two terminals of C1 (see photo 2).
• Install a green 2 terminal block in the place of U1 (see photo 3).
• Optionally: you may populate C2 if you wish to bring additional filtering to the board, however this should prove unnecessary.

Jumper Installation (Photo 2)

Terminal Installation (Photo 3)

DISCUSSION: The jumper across C1 simply shorts the unregulated side of the voltage regulator, U1, to ground.   This brings ground to pin 1 of the U1 pads, thereby bringing ground to the terminal strip.  Installation of the terminal strip places the terminals over the unregulated, input, side of U1, and the regulated, output, pads.  The left terminal will be ground, the right terminal +5.

NOTE: C2 is left functionally intact, so this could be populated with a suitable capacitor should noise on the 5V line prove to be a problem.

ON BOARD ZEROCROSSING: Elimination of the transformer also eliminates the on-board generation of the zero crossing signal.  This can be easily rectified by performing the following modification;

(CAUTION: this will place 120VAC in unexpected places on the board, use standard safety protocols when working on a live board, as you should be doing anyway.).

• Run two jumpers from the primary pads of TF1 to the cathode sides of D1 and D2 respectively. (See photos 4 & 5)
• Replace R1 and R2 with 22K Ohm 1/4 watt resistors (the 27K resistors used as pullups elsewhere should be sufficient).  (Refer to photo 2 or 3)
• Populate U2 as usual.

Primary Detail (Photo 4)

Diode Detail (photo 5)

REN-T LIKE ZC: I decided to use an outboard, master zero crossing generator, like the REN-T, a all in one 5V supply, RS485 converter, ZC generator outlined in the ChristmasInShirley.com Wiki.

Addition of this capability is very simple, run a jumper from pins 7/8 to the ZC test point on the SS-16 board (see photo 6).  It may be desirable to remove R9, the 27K Ohm collector pullup resistor on all but the very last board in the string.  With my 4 boards, the parallel resistance of these resistors will add up to 6.75K ohms, a bit strong for a pullup.  Simply unsolder one end and bend off the board.

ZC Jumper Detail (Photo 6)

IN CONCLUSION: These modifications are as yet untested, but should, in theory, work.  Any updates will be posted here.