| Electronics > Projects, Designs, and Technical Stuff |
| Adjusting voltage of Dell Power Brick Laptop Adapter |
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| X7JAY7X:
I have a Dell P/N FWCRC ADP-240AB D laptop power supply that I am trying to modify for 24V. See pictures. There is an error in the picture, the DAP09 should be DAS09. I have identified some of the components but I cannot find the datasheets on the DAS09 or DAP026A. I believe the two DAS09's are the feedback but am a little stumped on how to modify this. The two DAS09's go to the leftmost opto. I am also not sure what the LM393 and OPA22UA are doing. Any help would be greatly appreciated. |
| coromonadalix:
For what purpose do you want this modification ?, you may have poprietary parts cpu or pwm ic in there ... they are 19 vdc adapters and pushing it to 24vdc can create more problems than solutions, you will affect load and line regulation I would advise to find an already made 24vdc adapter or an switching power supply ... |
| X7JAY7X:
It is for a 3d printer. I am looking for something small, slim, and no fan. Not many power supplies fit that bill. Plus, I have several of these just laying around. My electronics experience is mostly limited to microcontrollers and simpler circuits. I am not that familiar with power supplies other than the concept how how switch mode supplies work. Why will the L-L regulation be affected? How much are we talking about? |
| tunk:
I don't really have a clue, but there's something like a transistor called IC134 which possibly could be a TL431 (bottom left on IMG_20200220_225228.jpg). There's also a few ZDs at the bottom of the PCB which could be Zener diodes. |
| Prehistoricman:
For the feedback path to the mains switching side, there is usually a voltage reference on the secondary side that is compared to a divided voltage of the output. To adjust the output voltage, either change the reference voltage (if it's adjustable) or the divider ratio. As tunk mentioned, TL431s are common voltage reference ICs. To get a start, you could scope the secondary side of the opto-isolators to see which one is responsible for transmitting this "too high, too low" signal. |
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