Printer - Brother 110 Laserprinter

[anishkgt]

Hi All,

Am trying to test this board of a Brother Laser printer 1110. Would the heat-on on pin 3 switch ON the heating drum, if connected to GND on the board ?

[Cupcakus]

Without a schematic I'm not sure how helpful I can be, but I've worked on a fair share of laser printers... You can be sure a relay of some sort turns on the fuser filament, is there voltage on heat-on?

[anishkgt]

Thank cupcakus! Yes there is it is pin 3


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[Cupcakus]

Well I'd briefly connect it to ground and if you hear a relay switch you have your answer.  Not knowing this printer I would not run it like that for any length of time.  Be very careful, high voltage will be present.

[xavier60]

Looks like there is a triac on the live side, and likely to be driven by some sort of opto-coupler. Then I wonder what the relay is for.

[anishkgt]

Yea I guess will just quickly connect the relay on pin and heat-ON on


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[anishkgt]

Yea there is one, am guessing that is controlled by pin 3 shown in the second pic.


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[xavier60]

Voltage must not be applied directly to the LED side of opto-couplers, there needs to be a current setting resistor in series.

[anishkgt]

Not sure if the opto has anything to do here. Will have to see how pins 2 and 3 works when connected to GND.


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[jdraughn]

I would measure resistance between that pin and gnd, and that pin and logic voltage to see if it's pulled up or pulled down.

[anishkgt]

Would the logic voltage be 5 ?


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