Ok so I have an Amstrad 6128 and I did the piggyback method to rule out which ram could be the issue (it has the black border and solid colour screen, no text or garbled graphics).
I piggybacked a new ram chip ontop of the one on the bottom right and it all worked! basic screen came up and it was just that one ram chip.
fantastic. so i desoldered the faulty chip and as i pulled it...
there was this tiny thin wire soldered underneath the chip, it was short (about 1cm in length) but it broke away soon as i began lifting the chip!
pictured you can see it was wrapped around the 3rd left from the left on the bottom row.
(https://imgur.com/gallery/QQBcglF) https://imgur.com/gallery/QQBcglF
now when i turn it on with the new ram chip installed.. nothing. just the black border and solid colour screen again!
what did this wire do?
it worked when i put the new chip ontop of the faulty one so this wire definitely did something.
thank you
maybe from a previous repair a PCB track/solder point was damaged and the connection was repaired with this wire. Check if there is a connection between Pin3 of all ICs. If any connection is missing, solder a wire from pin3 of the not connected IC to pin 3 of a connected IC.
That "thing" in the picture is the copper that was in the hole that connects the top and bottom layers of the PCB (the via). The "wire" was most likely the PCB trace that you tore off the PCB while removing the chip. Solder a small jumper wire between pin 3 of this chip and pin 3 of the next RAM chips on either side and it should work again. Pin 3 is the write enable, they are all connected in parallel from one chip to the next.
Bryce.
excellent this makes sense to me now, I will try this tomorrow. I was tearing my beard out today with repairs going wrong (i have no hair on top left haha).
When it fired up all good when testing the ram chip on top i was so relieved and ready to move on to the next repair (xbox one controllers :'( ) When that wire came out it was a case of just another repair being set aside, so this advice will save me a whole load of time tomorrow thank you
And I would recommend the solder side... So just solder the Ram Socket in, and then connect the lines on the backside.