Brother DCP-L2500D - completely dead

[spleenharvester]

Hi everyone

I have quite a bit of experience with low voltage circuits but basically none with high voltage circuits outside of recapping. So if anyone could point me in the right direction I would appreciate it very much!

This printer, history unknown, has no signs of life when plugged into 240VAC. It has the LT2988-001 board common to many Brother HL-2XXX series printers. The only physical abnormality observed is a green tint to the positive leg on the main 400V filter capacitor. This model is prone to shorts across the four Schottky diodes but all are testing OK by diode check on a multimeter. The two main fuses and one thermal fuse all have continuity. The inductors all have continuity. NTC1 measures about 8ohm to neutral when unplugged. Z1 measures no continuity when unplugged.

Pics attached. Thanks everyone

Edit - nvm I'm being an idiot there is 330V DC across the large cap, 16V and 3V at the output pins as expected so edited the above. There's a video of an identical case and someone says it's the MIP005 IC so I may try that

[spleenharvester]

Found a shorted resistor during testing, replacing it had no effect however. After that I accidentally damaged the board irreparably during testing so I have abandoned this.

[stj]

lol
unless you fucked a transformer anything is repairable
if you had low voltages but it was running then optocouplers and any 431 voltage reference would be suspect.

[spleenharvester]

I didn't quite clean off the 99% IPA enough before plugging it back in to take more readings and the entire board caught fire momentarily and melted all the connectors haha. Between that and getting several zaps I think I'll stick to repairing lower voltage circuitry for now, clearly it's not for me! Before that happened the FET neighbouring the resistor was looking very suspicious though

I managed to get a new PS off aliexpress for £22 so hopefully that fixes it

[stj]

connectors are cheap and easy to get from junk,
how much ipa did you use exactly??

[spleenharvester]

Apparently far too much haha

Replaced the PS with the AliExpress unit today and it fired straight up - for anyone stumbling across this in the future it appears LT3251-001 and LT2884-001 are both crosscompatible with LT2988-001. Unfortunately I can't document what was wrong with the old board as the whole thing started reading short to ground after it caught fire, but I believe it was the large resistor + the FET next to it that were at fault.