exxos's Atari, Amiga & retro forum

Not many components on that board so should be a quick build.

stephen_usher wrote: 25 Mar 2025 12:23 Not many components on that board so should be a quick build.

Yeah, just waiting for the remainder of parts to arrive.

Should be done in a few days.

Looks good !

HigashiJun wrote: 26 Mar 2025 00:40 Looks good !

Thanks :)

Small issue though, it suggests on github that the board can be powered from the Amstrad, but I just don't think that is true, however once all the parts are here I should be able to test out the theory. I'm just waiting on IC's and some connectors.

In case it requires power I've got a PicoPSU coming and the way the schematic seems to work is that there is a 12v barrel jack into the ISA board, and that feeds the PicoPSU, which in turn powers the ISA board and the Amstrad PPC.

I have all the pinouts, so I should be able to adequately test the ISA board voltage outputs before I plug it into the machine, hopefully ruling out any chance of magic smoke!!!

rubber_jonnie wrote: 26 Mar 2025 00:54 Small issue though, it suggests on github that the board can be powered from the Amstrad, but I just don't think that is true, however once all the parts are here I should be able to test out the theory. I'm just waiting on IC's and some connectors.

I guess the Amstrad is powered via an AC/DC adapter.

In such case, you can still use a splitter to power your machine and the board at the same time (provided the voltage is the same):

HigashiJun wrote: 26 Mar 2025 05:18

rubber_jonnie wrote: 26 Mar 2025 00:54 Small issue though, it suggests on github that the board can be powered from the Amstrad, but I just don't think that is true, however once all the parts are here I should be able to test out the theory. I'm just waiting on IC's and some connectors.

I guess the Amstrad is powered via an AC/DC adapter.

In such case, you can still use a splitter to power your machine and the board at the same time (provided the voltage is the same):


Splitter.jpg

It has a single 12v input and if I'm reading it right (not 100 % sure) the ISA board has a spot to plug in the PicoPsu and a power connector, plus a connector on board to serve the PicoPsu with 12v.

So the power brick I'm using at the moment would power the ISA board and the ISA board then powers the PPC over the expansion connectors.

It's a bit janky but means no need to split the 12v power, it'll just go into the expander rather than the PPC.

Also, I found this in the service manual: "When an expansion unit is fitted, the PPC must be powered via the expansion connectors." and that fits in with my understanding of what's what.

rubber_jonnie wrote: 26 Mar 2025 08:40 It has a single 12v input and if I'm reading it right (not 100 % sure) the ISA board has a spot to plug in the PicoPsu and a power connector, plus a connector on board to serve the PicoPsu with 12v.

So the power brick I'm using at the moment would power the ISA board and the ISA board then powers the PPC over the expansion connectors.

It's a bit janky but means no need to split the 12v power, it'll just go into the expander rather than the PPC.

Also, I found this in the service manual: "When an expansion unit is fitted, the PPC must be powered via the expansion connectors." and that fits in with my understanding of what's what.

Ok, get it now...

I didn't catch the end of your previous post.

Quite weird to power the Amstrad via the expansion.

HigashiJun wrote: 26 Mar 2025 09:42

rubber_jonnie wrote: 26 Mar 2025 08:40 It has a single 12v input and if I'm reading it right (not 100 % sure) the ISA board has a spot to plug in the PicoPsu and a power connector, plus a connector on board to serve the PicoPsu with 12v.

So the power brick I'm using at the moment would power the ISA board and the ISA board then powers the PPC over the expansion connectors.

It's a bit janky but means no need to split the 12v power, it'll just go into the expander rather than the PPC.

Also, I found this in the service manual: "When an expansion unit is fitted, the PPC must be powered via the expansion connectors." and that fits in with my understanding of what's what.

Ok, get it now...

I didn't catch the end of your previous post.

Quite weird to power the Amstrad via the expansion.

Yeah it is odd. Unfortunately there aren't a lot of instructions on the github, so it isn't really clear that this is the case, and it hints the expander can be powered from the Amstrad, but looking at the service manual, the power pins on the connector are all inputs to the machine and not outputs, then with the spot for an onboard PicoPSU it started to make sense.

Trouble is the 20 pin ATX connector I can only seem get from Ali Express, so I'll have to wait for those to arrive.

rubber_jonnie wrote: 26 Mar 2025 10:05 Trouble is the 20 pin ATX connector I can only seem get from Ali Express, so I'll have to wait for those to arrive.

:(

HigashiJun wrote: 26 Mar 2025 10:11

rubber_jonnie wrote: 26 Mar 2025 10:05 Trouble is the 20 pin ATX connector I can only seem get from Ali Express, so I'll have to wait for those to arrive.

:(

Indeed