Canon printer board repair

[adel87]

Hello , I have a canon pixma mp550 printer that doesn't work at all and I think the formatter (main) board is broken.
since I'm sure the power supply is working fine and has no any problem I think the problem is because something like a bad resistor or capacitor.
but I'm a newbie and I need help, the psu have 5 wires/pins and here is the information about each of them:
1: printer controller, standby 0V , working 5V+
2: gnd (-)
3: standby 8.5V+ , working 22V+
4: gnd (-)
5: standby 11V+ , working 31V+
normally when the printer is off it has the standby voltage and when it turns on it has working voltage, after pressing power button the printer should send something between 3.5 and 6 V+ to the psu from the wire/pin 1 and after that psu goes into working mod and ...
now my problem is when I press the power button nothing happen! the button working fine and connectors are good, but one strange thing is that the whole board instead having + VCC , is gnd (-) ! even after connecting the psu connector to the board, the wire/pin 1 instead of 0V or 5V+, it turns into gnd (-)!
I appreciate any help in advance.

 

[theupsstorelosan]

Here are a few steps you can take to troubleshoot further:

1. Check for visible damage: Look for any burnt components, bulging capacitors, or broken resistors on the formatter board.
2. Resoldering: Sometimes, cold solder joints or broken connections can cause issues. Resoldering any suspicious joints might help.
3. Replace components: If you identify any faulty capacitors or resistors, replacing them could resolve the issue.
4. Consult a professional: If you're not comfortable with these steps, it might be best to consult a professional technician.