exxos's Atari, Amiga & retro forum

I think this is as far as I should sensibly go until the missing IC and dip sockets show up next week.

I'll probably do those first with the last crystals etc, then the resistor networks and then all the connectors/sockets, with pin-headers last so there is less chance of getting pins bent while turning the board over.

Note the size of that cooler & SIMM socket 0 :p close, but not quite!

dml wrote: 08 Jun 2025 13:13 Note the size of that cooler & SIMM socket 0 :p close, but not quite!

Oh.. so close but not quite a perfect fit! You could probably cut a little bit off it with a bandsaw :)

I recon there would have been just enough space for the cooler if the simm sockets sat more snug next to each other - they don't necessarily need that much space between them.

Fitting 45 degree angled Simm sockets might help?

If I could find someone with an end-mill, I could maybe lengthen the CPU indent/channel under the cooler and move it 4mm horizontally out of the way. But that's a big 'if'. I'll leave it alone for now. :)

Meanwhile, the missing IC and the DIP sockets turned up so I should in theory be able to finish building the main board very soon...

BTW some of the ICs so far had no indication at all for pin 1, except the orientation of the writing. No dot, no groove, no line. Nothing, top or bottom. So the probability I have at least one in backwards is ... > 0.0

@dml join the club with fitting stuff backwards :lol:

dml wrote: 11 Jun 2025 18:46 BTW some of the ICs so far had no indication at all for pin 1, except the orientation of the writing. No dot, no groove, no line. Nothing, top or bottom. So the probability I have at least one in backwards is ... > 0.0

KiCad pin 1 marking is not very clear but it is there. Sometimes it is a line, a square with a missing corner or the said missing corner!

You can also switch on pin 1 marking in the interactive BOM which is helpful. :)

sety wrote: 12 Jun 2025 02:10 KiCad pin 1 marking is not very clear but it is there. Sometimes it is a line, a square with a missing corner or the said missing corner!

You can also switch on pin 1 marking in the interactive BOM which is helpful. :)

Oh - I meant the components themselves, not the board. I found the board a little cryptic in places but the marking is aways there in some form :)

On closer inspecting one of those ICs under microscope though, I did find a marking in a place I didn't notice before - not on the top or bottom of the package but a very tiny indent/notch on the side of the package, just above the pin shoulder.

Surfacemount component MFRs are getting very economical with the human-readable information, even when there's space for it :)

dml wrote: 12 Jun 2025 08:24
Oh - I meant the components themselves, not the board. I found the board a little cryptic in places but the marking is aways there in some form :)

On closer inspecting one of those ICs under microscope though, I did find a marking in a place I didn't notice before - not on the top or bottom of the package but a very tiny indent/notch on the side of the package, just above the pin shoulder.

Surfacemount component MFRs are getting very economical with the human-readable information, even when there's space for it :)

Oh yeah! The industrial world is now using pick and place machines. Markings are obsolete, which doesn't help the home builder much. Caps are the worst. Put a strip of them in to the wrong container and the whole lot is a write off :lol:

A Poska pen can help. give the IC a dab of paint and wipe it off with your finger, if there is a pin 1 indent, it will show up good.

sety wrote: 12 Jun 2025 09:56 Markings are obsolete, which doesn't help the home builder much. Caps are the worst. Put a strip of them in to the wrong container and the whole lot is a write off :lol:

A couple of times I did that - I solved it by poking sharp probes through the film with a capacitance meter. But then its difficult to find space to write the value on the back of the strip as its mostly made of holes.

sety wrote: 12 Jun 2025 09:56 A Poska pen can help. give the IC a dab of paint and wipe it off with your finger, if there is a pin 1 indent, it will show up good.

Good tip!

I think I have assembled enough of this to start thinking about some basic tests - checking for shorts on rails, making sure +5/12v isn't appearing on the wrong pins etc... maybe some tests with power applied. And then move towards programming the ICs.