I also tried with vga card on the ISA slot and not only with vga port on the motherboard but that had no effect.
Checked voltages on the motherboard side of power connector(s) and they seem close enough. At least that
leads me to believe there are no shorts on voltage lines.
Inserting a VGA card in a slot will not be the only thing you have to do to try getting video output external to the onboard Paradise adapter. You have to deactivate the "internal VGA" first. That is done with an option link (AKA "jumper" for the rest of us).
All the relavent info regarding the option links is on the hardware page I linked to back in post #14 of this thread under the heading "1/2/3xxx DIP switches and option links." Where the "1/2/3xxx" in the heading can be translated into "model #s 1xxx or 2xxx or 3xxx", or in our case "2286" specifically. So that you don't have to hunt down the link in post 14, the URL is
https://web.archive.org/web/20101216023809/http://web.ukonline.co.uk/cliff.lawson/atpcs.htm.
RAM chips seems to be tms44c256-12N chips, 256kx4bit chips. I don't think I have anything that I could test these out with.
They are all socketed. I tried to pull and push them back, did that also on ICs 149-152 that were socketed but that did not help.
I'm guessing these bigger ICs may be bios and keyboard ROMs.
Yes, how many banks are there? You may try swapping them around. Also just reseating them can sometimes help.
I agree RAM swapping is a good idea to try to get the machine running. But, for a complete understanding of memory configuartions on this machine, read the section "Adding memory" on the above link. Adding memory is really one of the best things you can do with the 2286. I've been able to install a full 16MB on these machines maxing out the 80286 addressing capabilites. The motherboard has an onboard LIM EMS system also. This allows you to use the entire memory as extended, EMS or XMS memory and in combinations just like it was a 386. (The special MEMM.SYS driver available on the system disks is needed for using the RAM as EMS.)
There are no sim rams on the slots. I think they are not mandatory since the smaller sims make 1Mbit of RAM. I might find
30 pin sims from some other old pc I have lying around to test the board with, but I'd need to know jumper setting to make
the change. I'm guessing the smaller RAM chips need to be pulled out before 30pin sims could be installed.
Again, the info you need is in the "Adding memory" section. But, briefly, you guessed right: you would have to pull out the RAM chips first, the system wasn't designed to use both memory types at the same time. Also, not just any 30 pin SIMMS will work. The details are on the above link. (Hope no one got sick of me saying that over and over.)
I'm wondering if failed RAM chip will prevent the motherboard from POSTing? This new trouble was a shame and
a bit surprising too, since the motherboard does not look corroded.
Especially if the first addressable RAM chips are bad, the POST probably won't run. While I can't be sure on the 2286 because I never had any bad RAM chips installed on one, I know that some BIOSes do use the first 64K for data storage, etc during the POST.
One final note: While searching the internet for more data about the 2286 service manual, I came across this thread on another forum:
https://www.cpcwiki.eu/forum/other-retro/amstrad-pc-2286-help/
Coincidentally, there is another 2286 in the process of being restored. I thought you might want to join that forum and invite the other owner/restorer to join in on the process over here. Perhaps the 2 of you can benefit from the help from both forums.