How to adjust the printhead on a dot matrix printer?

Question

We have an Epson LQ-590 that we use for pay slips. Our problem is that it's printing "too hard", in that you can read the print on the cover sheet of the slips, and you can quite easily make out the details.

We've pulled the slider right back to 7, but it still prints through. We almost need an 8th option on the print head adjustment.

Is there anything we can do to manually pull the printer head back a bit further?

Answer 1

Not sure about your model, but there used to be two main methods to set the default spacing between the face of the printhead and the platen called the PH gap.

Before you try to reset the PH gap, try and remove the print ribbon, move the gap lever all the way back and look at the printhead face. The pins and the small ruby chip that aligns them should be flush with the front of the printhead. If the pins and/or the ruby chip is not flush - especially if the ruby chip is recessed and the pins are forward of the front of the printhead - this would indicate the printhead is worn out and may need to be replaced. The pins sticking out from the printhead would cause the strike to be too hard. Otherwise you can try...

On those models with screws that held the heads and slotted holes on the printhead, you would set the gap lever to like level 2 (next to closest to platen) and then space with a single sheet of 20# paper. Then push the printhead gently up to it and tighten the screws. That would set the gap.

On those where the printhead snaps in or the screws won't allow for adjustment, sometimes you had to disassemble the printer, unscrew the gap lever, spin the adjustment bar to set the gap with a piece of paper like before and then rescrew the gap lever at the level 2 position.

Answer 2

It's been a while, but have you tried removing the paper and reloading it to see if the print head adjusts itself properly? Also, have you verified the paper thickness setting?