I have a "GE 7.5 foot" pre-lit Christmas tree that was purchased from Costco some years ago. This tree has a small hard-wired controller box with four settings: white, white/colored (fades back and forth), colored, and off. Last year, the lights failed, and I replaced the 29v DC power supply with one from Amazon (TS-18WL29V) which was somewhat higher wattage. The new power supply worked for a short time (tens of minutes) and then the string failed again. I have determined that the power supply still works, but the controller box has failed. Connecting the DC power supply directly to the strings (of which there are approximately 8 on the tree) lights them up in the white color.
The controller box takes in the 29VDC and outputs... two wires. Opening the controller box shows what appears to be a set of MOSFETs in an H-bridge configuration. I am guessing that the LED "bulbs" on the tree actually contain two LEDs, one white wired in one polarity, and the other colored and wired in the reverse polarity. I have theorized that the controller box simply swaps the polarity of the power to the LED strings to choose between colored and white.
Is this accurate? Is this a "standard" configuration? Could I replace the controller with something easily (and cheaply) obtained? Is it safe to drive the LEDs directly from the DC power supply, or do I risk damage to them by driving them at too high a current, in the event that the old power supply's lower current limit was serving as a limit to the current in the LED string? If this is the case, could I set up a simple MOSFET driven via PWM to limit the current to something safer?