HP97 The journey begins

[teenix]

(10-21-2023 06:40 AM)Didier Lachieze Wrote:  Nice ! Do you use any specific fixture to maintain the board to board pins when soldering them?

It is lucky that the pin spacing in these models is 0.1". I have some narrow inter-connector PCB's with the same hole spacing so I drilled the holes out to 1.3mm which is a nice fit for inserting the pins. A narrow strip of prototyping 0/1" matrix board, drilled as well, would do. You could use the holes in the LED display board, but there is a risk of damage.

Then I loosely put in two end pins and place the strip board over these pins to hold them roughly in place. It is relatively easy to square up the two pins up by eye and then I solder one, verify and minor adjust if necessary, then solder the other. These now serve as place holders for the rest.

I then add more pins at either end, slide the holed board over which keeps the pins in place, a quick verify/adjust then solder them, continuing towards the center.

The 19C has an extra row of pins angled to the print-head board, so I used the newly soldered side pins to hold the 2 boards aligned then it was easy to match these other pins.

The display pins are angled also (30 degrees) but luckily the PCB hole size allowed to pins to sit at pretty much the right angle.

It sounds like a lot but is easy in practice. The tedious part is redoing all of this if there is a board design problem.

cheers

Tony