82240B printhead fried itself in a puff of smoke

[teenix]

(02-26-2018 04:08 AM)tcab Wrote:  Can anyone suggest how to remove the ribbon cable? There seems to be no unclipping mechanism. Pulling on the cable seems fruitless. There are some ribbon cable removal techniques listed here but I can't seem to find the exact scenario that matches the 82240B.

Perhaps if I push a flat headed screwdriver in and try to lever the pins away from the cable, as I pull?

Ribbon cables usually pull out easily, unless there is a locking mechanism on the socket which doesn't look the case.

Its hard to tell, but does the ribbon connector have screws on the side - maybe they are tightened to hold the cable firm in the socket.

It looks like one or more of the heating resistors in the print head have overheated for some reason, even though the head is supposed to reach temps of up to 350 degC. If they shorted, I might expect the ribbon cable to show signs of heat damage as well because of the high current.

The driver circuit (PIK chip and associated high power driver) could also have failed causing the high drive current to be applied for a lot longer time than normal, which is only a short pulsed signal of around 5mS I believe. As the head elements heat and cool very fast, I don't think they would last long if turned on for extended periods. It would be terrible to replace the print head and have it fail again.

cheers

Tony