LC III - Will it ever run?

[stephen_usher]

Right! I need a microscope. One ordered from Amazon.

Taking a picture and blowing it up shows all the pins all over the place, so I'm going to have to take the chip off again.

[stephen_usher]

Looking on-line there is, in fact, a QFP pin straightening tool. However, and it's a big one, it costs £265!!! But with free delivery.

No other hits on Google other than this: https://kaisertech.co.uk/lead-straightener-qfp-tool

[peters]

Is that too small to 3D print an alignment block ?

[stephen_usher]

Is that too small to 3D print an alignment block ?

To align the pins horizontally, yes. There is a gap of less than 0.2mm between the pins and the resolution of a filament 3D printer is 0.4mm. You could make a block to align the bend in the pins, however.

[stephen_usher]

The CPU is back off and no extra pad damage.

IMG_3632.jpeg (340.67 KiB) Viewed 2070 times

As you can see here the CPU's pins aren't exactly fully straight.

IMG_3633.jpeg (251.29 KiB) Viewed 2070 times

[lilwashu]

The other CPU was much the same - I hope you have better luck with it than I did. I’m pleased that the pads are mostly still good as I must have put quite a lot of heat into some of them trying to get the pins to sit flat/straight.

[stephen_usher]

Designed and 3D printed a former for the chip legs.

IMG_3634.jpeg (281.13 KiB) Viewed 2049 times

Although it can't fix the spacing between the legs it does allow the legs to be bent into shape and the correct distance from the body of the chip both vertically and horizontally. It also allows the chip to be held securely to tweak the leg spacing whilst not disturbing any of the other legs.

I've since offered it up to the PCB and it's made a world of difference. I have a chance of soldering it correctly now. It's not perfect but it's huge improvement over how it was previously.

[peters]

Nice one.

Is the printing resolution good enough to align pairs of pins ?

[stephen_usher]

I'm afraid not. The legs are separated by approximately 0.2mm and the width of the extrusion is 0.4mm.

I was thinking of an upper former which would press down and force the legs to conform to the shape.

[rubber_jonnie]

Designed and 3D printed a former for the chip legs.


IMG_3634.jpeg


Although it can't fix the spacing between the legs it does allow the legs to be bent into shape and the correct distance from the body of the chip both vertically and horizontally. It also allows the chip to be held securely to tweak the leg spacing whilst not disturbing any of the other legs.

I've since offered it up to the PCB and it's made a world of difference. I have a chance of soldering it correctly now. It's not perfect but it's huge improvement over how it was previously.

Nice