Defeat the 1 Minute Automatic Shutoff of the Derma Spec 4 Watt Blacklight!

updated 8/5/2001.

This requires some electronic reapir skill. Do this at your own risk. Also, this unit is not of really good quality anyway - at least the price is right if you get it from Hosfelt Electronics or Electronic Goldmine or All Electronics.

Now for the hack: There are two steps: 1. Locate C1 which is a 47 microfarad electrolytic capacitor near R3 which is a 1.2 meg 1/4 watt resistor. Short this capacitor. You would want to solder a small piece of wire or add a large blob of solder across this capacitor's terminals. This step alone will defeat the automatic shutoff, but now a transistor in the circuit can overheat.

2. To avoid overheating a transistor in the circuit, find the heatsink with that transistor in one corner of the board. You need to add some sort of extension to this heatsink.

I soldered two 6-inch lengths of 10-gauge stranded wire to the heatsink. It is tricky soldering to aluminum - use fine sandpaper to scrub off the oxide layer and immediately tin the scrubbed area. Do this only towards the ends of the heat sink fins to avoid cooking the transistor during soldering. Do the tinning as quickly as possible with a high wattage (~40 watts or more) iron. You may need to push around a blob of solder on the freshly scrubbed aluminum, lightly scrubbing it again with the soldering iron tip in the process.
After solder is solidly stuck on at least two points of the heatsink, allow the whole heatsink to cool and then solder on the two pieces of 10-gauge wire. You probably want this wire to be insulated. After the wire is soldered in place, you probably want to add some epoxy somewhere on the board to keep the wires from breaking off from the heatsink.

CAUTION - Hack this unit only at your own risk.

CAUTION if you operate this unit while it is open - high voltage is present. I also recommend operating it only with a 4 watt fluorescent tube in place. Operating the unit unloaded may result in excessive voltage spikes in some of the circuitry.


ANOTHER HACK - Converting the unit to a 120 VAC unit.

Suggested by a website fan who did not get the hack above to work for him...

Remove the board and replace it with a 4-6-8 watt fluorescent lamp ballast. This part is a little hard to get but may be available at some hardware stores and at some electrical supply shops. You will have to rebuild the circuit using the usual "preheat" fluorescent lamp circuit in The Fluorescent Lamp Document. You will have to add a starter or a push-to-start momentary contact pushbutton. Hacking the board to make use of its start button will work, but it seems to me that the contacts of that on-board button will eventually be oxidized by sparks.


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Written by Don Klipstein.

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