Optoma EP716 Projector, No Power - Page 1
Forum section: electronics / repair

author: LiftedTrace
author_rank: Regular Contributor
timestamp: July 12, 2025, 01:50:43 am
content: Ive been racking my brain on this for a while and I find I keep running in circles on why this power supply wont start up. I dont know enough about it and I feel I am caught in a chicken and egg scenario trying to track down whats wrong.In the first pic, I have 155V across the main cap, and no activity on the transformer for the output (taps circled in red)In the second pic, I have 0v getting supplied to the power factor chip (ICE1PCS01), and that chip seems to be fed from the smaller one that is labeled 8K. From what I looked up, assuming I found the right one, its a voltage regulator, a 12v voltage regulator and it supposed to be provided 19ish volts on the pin where I measured 0.I tried to track down where this comes from, but it seems it comes from an output I dont have, that comes from the chip thats not getting powered....I put a oscilloscope on a few points and I dont even see a blip like something is trying to startup. Nothing on the pin powering the voltage regulator, nothing on the pin powering the power factor chip, nothing on the outputs or inputs of the transformer.I found a YT video on testing opto couplers by providing a small voltage and low current on the led side and measuring the resistance on the transistor side. I did that to both the opto's on this board and they both changes values with varying voltages...so I am guessing they are ok.The power factor chips gate pin is connected to the gate of a 20N60C3 CoolMos.The CoolMos seems to be connected to another coil device with three taps from I can see. I thought it was a transformer, but I'm not sure.Im pretty lost and could use some help.Thanks.

author: Harry_22
author_rank: Frequent Contributor
timestamp: July 28, 2025, 07:57:38 pm
content: Hi,could you add back side photos.Don't worry. We will check it step by step.

author: LiftedTrace
author_rank: Regular Contributor
timestamp: July 29, 2025, 07:59:33 pm
content: I was all happy when I got a response to help me troubleshoot this so I sat down, was going to snap some pics with some scope measurements and stuff.I had to solder a wire on to get some scope points and well, I got side tracked when moving the wire from point to point to gather some good pics to help this endeavor out, and wouldn't you know it...I was distracted and forgot to turn power off. Soon as my solder iron touched the solder, I let the smoke out....of the transformerMain winding is open as well as the winding responsible for powering up the high voltage section.So...thank you for the offer to help, but this power supply is dead.

author: Harry_22
author_rank: Frequent Contributor
timestamp: August 02, 2025, 04:34:07 pm
content: Hi!Shit sometimes happens.Don't operate with SMPS while it connected to mains. Always use DC power supply.Sorry for the delay. Sometimes it's hard for me to keep up with messages, especially those that are late in responding.Anyway, please send me the photos.I'm not sure your transformer is dead.

author: LiftedTrace
author_rank: Regular Contributor
timestamp: August 05, 2025, 01:23:11 am
content: Here are some pics of the board.No worries on talking a while. This power supply aint going anywhere.