I'm attempting to repair my friend's "DermaWand". It's supposedly a skin-improving device sold on late night TV.
Anyway, the device produces a glowing spark inside a glass tube very much like those toys you see in the toy and hobby shops that look like lightning inside a glass ball (Tesla's plasma ball). The "lightning" is attracted to your skin when you touch the glass. The DermaWand's output is contained in a small glass cylinder about 1/2" in diameter, with a flat end that is applied directly to the skin.
The one I'm working on does glow, but my friend complains that the intensity is too low and not nearly as much as it used to be. Turning the knob has little or no effect. I've verified that the pot is fine and working, the resistor values match their color codes, and the diodes have about 650mV across them in the right direction. D2 and D3 show open in the wrong direction, and D1 shows about 2V but the schematic shows why.
I'm thinking the triac, as the only active component, is suspect. But I don't have much confidence in being able to diagnose this simple circuit. The coil and tube are pretty much a black box (literally).
Any ideas?
Anyway, the device produces a glowing spark inside a glass tube very much like those toys you see in the toy and hobby shops that look like lightning inside a glass ball (Tesla's plasma ball). The "lightning" is attracted to your skin when you touch the glass. The DermaWand's output is contained in a small glass cylinder about 1/2" in diameter, with a flat end that is applied directly to the skin.
The one I'm working on does glow, but my friend complains that the intensity is too low and not nearly as much as it used to be. Turning the knob has little or no effect. I've verified that the pot is fine and working, the resistor values match their color codes, and the diodes have about 650mV across them in the right direction. D2 and D3 show open in the wrong direction, and D1 shows about 2V but the schematic shows why.
I'm thinking the triac, as the only active component, is suspect. But I don't have much confidence in being able to diagnose this simple circuit. The coil and tube are pretty much a black box (literally).
Any ideas?
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