Testing a Logic board for a Canon MP500?

Hello Folks,
First of all, I'm very impressed by this high quality level of informations in this Forum
Great people, very Helpfull!!
Thank you all to be here!!
My question:
Walking on the street last month, I found a lonely Canon MP500 on the top of a trash can.
There was a reason of course.
I couldn't imagine this beautiful symbol of technology collapsing on a mountain of garbage...
Took it with me like if it would be an injured animal.
Brought it home and started to try to fix it.
First steps, it started!!(Magical moment)
There was still ink on the Cart...
I connected it to my computer (Mac) via USB port and tried to print a .pdf file... Blanck paper...
Started to get interested in and found on the web that it might have been clogged with some old ink.
I printed a Nozzle check (see picture) and found out that there were a problem with the PGBK cart.
I cleaned the printhead ... dried it properly but nothing went better.
Some days later, I found on a web site the same model for sale, the owner told me "the Power supply is dead and it doesn't turn on".
Brought it home, controlled with a multimeter the power supply and found out it was working.
I tried it on my Printer, turned it on... was working.
Tried mine on the second printer: dead.
Than a 2 weeks later, in the morning, my printer wich was working, but not printing black, collapsed too. It was on for 2 weeks (I read that every time you switch it off and on, it use a lot of ink).
I must say I did a "Deep cleaning printhead" via the gear it self before (is that the reason?).
Then I got an Error Message with the Orange "Alarm light" blinking... and the Screen turned black after showing "Error 6300" and than it stopped and never came back to Resurrection...
Does anyone could have an idea if it would come from the Logic Board or from the Printhead ??
Any possibility to control it ?
Than how to test it ?
I do have 2 great MP500 but not one is working... hahaha!!
I like the challenge to bring both of them to life again!! ;-)
Best regards and hopefully I'll get some answers

Can you give us some more information on your rescued pets ?
How many orange flashing lights did you get, please count them and report back..

Hello "The Hat",
Thanks for replying... unfortunately as I remembered, it flashed many times and than it stopped for ever.
I tried to bring back to life but nothing happened...

You find a service manual for the MP500 here, and a parts catalog for the printer here. The service manual has no info about the output voltages from the power supply, but they might possibly be read on the bottom of the power supply. For testing the power supply and info about the interaction between the logic board and the power supply, see this thread. It is not the same power supply, but you can use the same method for testing.

The print head for the MP500 is the same QY6-0059 as used in the iP4200, so the info in the service manual for the iP4200 about the pin out of the of the power supply might also apply to your power supplies. You find a link for the iP4200 service manual in the thread I linked to.

Thank you very much Peter for your Wise advices.
I will make a cable and control it as you did.
But I tested already both of the PS and they deliver the right Voltage.
I just think that there was a problem with the Printhead which burnt the logic board on both cases...
I will try anyway.
Tousend Tak

If the power supplies deliver voltages, even if it is only the low standby voltages, I think they are OK and sadly the print heads and/or the logic boards are defective.

Both a defective print head and a defective logic board can prevent the printer from turning on, so you could try to remove the print head and try if the printer will now turn on. If the printer will turn on without the print head, the print head is defective and there is a chance that a new print head will revive the printer. But a defective print head can ruin the logic board and a logic board that has been damaged this way can ruin a new print head, so replacing the print head is risky.

If the printer will not turn on with the print head removed then the logic board is defective, making the printer a total loss.

To remove the print head you might have to remove the the printers casing, as the print head might be locked in place at the purge station. Maybe one of these workshop articles from druckerchannel.de will be useful for disassembly? Here is an instruction for MP530 and here is an instruction for Canon AIO's. You can use Google Translate to translate into English or French if you don't read German.

Super Peter!!
Danke vielmals, ich verstehe schon Deutsch!!
Many thanks for all this links.
I keep you posted as I'll be back home.
Best regards

You're welcome.

Your Danish "Tusind tak" = 1000 thanks = thank you very much, was almost correct

Hello there,
I was thinking about something...
would it be possible that because of a defect or clogged printhead the mother board could burn component like capacitor for example...because both of the MP500 I got had a clogged or "defekt" printhead...and all this printer are already old... capacitors do have a limited life, specially if there 're cheap.
My interest for Printer became bigger and bigger as a friend of mine asked me to fix her Canon Pixma IP4300 with a similar problem as mine...
Thinking that power supply burned out and than printer is dead... No sign of life, breathing or what ever... No noise, no response... I read some thread and I can see that from a day to another Canon printer stop to work and get very silence for ever...
Like if they would be a kind of fuse or component which give up
Could you imagine that??
I read remarquable explanations from Canon clogged printhead from you Peter and some very instructive thread from Grandad35...
Whatever it seems Canon developed a kind of Fragile concept... It sounds incredible to me to be oblige to change the Motherboard because of a clogged printhead
I haven't look yet at my 3 different Motherboard... But I'm very interested having a look at it.
I'll do it asap...
First I need to be home!!

I think you got Canon a little bit wrong when it comes to a clogged print head.

When you follow the correct procedures a Canon printer will work fine, deviate from that and you can land in trouble but by following some simply steps the printer will last you for years.

If you use the recommended OEM inks and you hit a snag (Like a clog) this will show up as poor output which can then be cleared easily by the printers own maintenance routine (Head clean).

Most head clogs are not in fact heads clogs at all but the inability of the cartridge to deliver sufficient enough ink to the heads which results in poor quality printouts and replacing the offending cartridge will in most cases cure this problem.

However if you continue to test print while experiencing poor quality output, then this usually leads to permanent nozzle loss and damage to the print head (Burnout).

Logic boards very seldom get damaged from this and the purchase of a new print head usually solves the problem and the printer will print again properly, the logic board can however get damages when the print head gets flooded with ink or is put back into the printer after cleaning it while still wet or damp.

The best solution to solving a printer’s problem is to print and examine a nozzle check first and if the printer fails to print then to count the amount of times the alarm LED lights on the front of the printer are flashing !

If you then take the necessary steps and follow the error messages you can usually get the printer back working, one further point which is vitally important when the print output is clearly poor,you should stop any further test prints till you can resolve this issue...