My summer project: A colour Stacy

[derkom]

Only issue I've seen with more and more caps can be the inrush current when all are fully discharged; that might increase the loading on the PSU start-up.

Shouldn't be a big issue with a refurbished PSU though.

This particular setup is running off a picoPSU with an 80W sustained limit, so it should be capable of powering several Stacys at once.

[JezC]

@derkom Should be fine then... wasn't sure if it was the original PSU.

[derkom]

@derkom Should be fine then... wasn't sure if it was the original PSU.

Nah, part of the whole situation here is the elimination of the original internal DC-DC PSU, which sits totally in the way of being able to do anything with the CPU, which sits directly beneath it.

I actually am using the "original" external PSU, original in quotes because it's really a Sony PSU repurposed. It's got 16.5V @ 3.9A output, so actually that's going to be the limit, at around 60W. Still well more than enough.

[derkom]

Pop a 100uf cap on the board and hopefully that'll help.

Just looking through my supplies here and thinking about what I could use. Isn't 100 uF rather high capacity for this job? The decoupling caps immediately next to the ICs on the H4 are 1 uF. I do have some of the 100s left from the H4 project, but since they're SMT, they'd be a little tougher to bodge onto this board than the 1 uF THTs.

I just checked on the TF536 and I see that the caps there are something in the neighbourhood of 50 uF (and there are indeed two of them).

Incidentally, still no issues after that one spontaneous reboot. Maybe the fridge clicked on and pissed it off or something.

[PhilC]

@derkom i used 10uf on my H4s, so its not overly important what size I guess?

[derkom]

@derkom i used 10uf on my H4s, so its not overly important what size I guess?

I did a little reading around, and it seems like 1-10 uF are the ranges people typically are using for ICs. But it's all a bit of voodoo I don't claim to understand.

Still no second crash anyway...

[derkom]

TF536 installed, proudly showing off @PhilC's handiwork...

IMG_20200729_193417.jpg (151.59 KiB) Viewed 2625 times

The CPU relocator is designed so that when the keyboard is installed, the TF536 will tuck underneath it all the way up to where the 68030 is. I've done all the measurements to verify that this will work vertically, but I can't actually see that for certain until I eliminate the socket on the relocator and solder the TF536 on, which won't be happening with this version. It fits on paper at least!

And a quick GEMBench (no maprom, no alt-ram, just showing that it works)...

IMG_20200729_193345.jpg (129.68 KiB) Viewed 2625 times

I'll probably leave this looping for a while.

[derkom]

A quick picture to show how this works in relation to the keyboard. Right now the keyboard can't sit flat, because various things are too tall in this temporary configuration.

IMG_20200729_194727.jpg (122.18 KiB) Viewed 2622 times

[PhilC]

@derkom looking good. Never seen a Stacy in real life, what are the rough dimensions?

[derkom]

@derkom looking good. Never seen a Stacy in real life, what are the rough dimensions?

When closed, around 38x34x9 cm.