exxos's Atari, Amiga & retro forum

@exxos I should be able to try it in an STM & Mega.

Well dang! Once I clear out a few projects I'll need to pick up a 288xl and update at least one of my ST536's (probably both eventually)

Just looking at pricing for them on Mouser in the US and they're up to around $100 USD per....

PhilC wrote: 26 Oct 2025 20:25 @exxos I should be able to try it in an STM & Mega.

Cool. Will PM you when I am done messing about with it :)

exxos wrote: 26 Oct 2025 20:43

PhilC wrote: 26 Oct 2025 20:25 @exxos I should be able to try it in an STM & Mega.

Cool. Will PM you when I am done messing about with it :)

I'm going to get something from your store if you want to get it sent at the same time?

coonsgm wrote: 26 Oct 2025 20:35 Well dang! Once I clear out a few projects I'll need to pick up a 288xl and update at least one of my ST536's (probably both eventually)

Just looking at pricing for them on Mouser in the US and they're up to around $100 USD per....

Mouser take the pi$$ lately. I can send you some new chips, I got mine NOS and wasn't anywhere near that price , and they all genuine new as well ;)

PhilC wrote: 26 Oct 2025 20:44 I'm going to get something from your store if you want to get it sent at the same time?

Yeah makes sense. Probably need a couple weeks though to finish tests.. I'm not at home much this week , so won't have much time this week to do much.

exxos wrote: 26 Oct 2025 20:45

PhilC wrote: 26 Oct 2025 20:44 I'm going to get something from your store if you want to get it sent at the same time?

Yeah makes sense. Probably need a couple weeks though to finish tests.. I'm not at home much this week , so won't have much time this week to do much.

Lol ok well I've placed the order, please let Dawn know not to send it until you're ready with the st536.

PhilC wrote: 26 Oct 2025 20:48 Lol ok well I've placed the order, please let Dawn know not to send it until you're ready with the st536.

:chairsmack: :2k2:

I can probably get some more ST536 "birdseed" boards make soon if people can solder the socket and PLD themselves to finish the build. There needs to be more BETA testers out there before I even consider going for a small full production run (it's rather expensive!) .

Bad news from my side. I think I destroyed my first ST536 proto not one time, but three times ... :hide: :cry:

What do you think, which pin is +5V at PWR2 connector ?
No, it's not where the "+" is. This one is a fiducial :oops:


CPU and EPROM were already inserted, when I powered it via PWR2 and wrong polarity for programming. Both of them seem to have survived (Work in TF536 and Programmer). The CPLD also accepted programming afterwards and 3.3V also works, so CPLD is most likely still OK.
Unfortunately my Mega ST shows a pink screen, exactly, what it also does, when no processor is in.
So probably some 5V chip sacrificed itself to protect the others ? But which one ? I think I really can't trust the board anymore, so it may make some sense to build the second ST536 before trying a repair on the first one. I wish I had already one PCB working to rule out, that something doesn't work together with the ST's IMP chipset or the like.

I tried the latest EPROM image (26.10.2025) and the CURRENT7,18 and 20 firmwares. I didn't try the 8MHz though. Everything the same.
There are two jumpers on the bottom side (SJ1+2), which I didn't set. What is the purpose of these ? VCC was 4.98V all the time during testing.
"Mandatory" fixes are done (2.2k resistors throughout). I wish I had a schematic ...