actualreality

Thanks - I do want to stick with sockets. I bought full 2 sets of RAM as I change memory chips for people - my own Spectrum +2 and +3's for instance I removed the RAM and added sockets with no issue. Also done it to both of my C64's, again with no issue. I have now checked the RAM pins have the correct voltage to them, and they do - measuring over the VCC (Pin 8 +5V) and VSS (Pin 16 Ground) each chip is getting 5.25V to them, so can only assume that something else has gone pop since I changed the RAM. As you say, maybe the MMU or LS158's! I tried removing all socketed chips and re-seating them, but still nothing. Also tried turning the machine on with no ram chips in the sockets at all, but still nothing. Tried with the old RAM in which gave the error in the 1st place of 44 red squares - nothing again. Always particularly careful when I'm completing work like this. Definitely didn't snag any traces or pulled through any "bobbins".......... Edit: Just bought 2 x LS158's so will see how they fair. All is not lost as I have my eye on another 800XL in any case, but would be really great to get this one working as I have spent so much time with it

All the correct way round (took photos at every stage to ensure that they were the same way around. Chips pulled from the 800XL were MT4264-15 - replaced with KM4164B-15. From datasheets I cant see anything that would cause an issue. I did check for broken traces etc before I added sockets, all fine. I guess I will have to remove them all again and solder the chips directly to the board, making sure I solder above and below the board. cant solder above of course at the moment as I have sockets on it. Didn't think last night, but will also make sure each chip is getting a 5V supply and work from there I think.

Hi all I bought an 800xl from ebay last week. Plugged in and got 44 red squares and 4 green so ordered some sockets up and RAM chips (same as the C64 memory i believe) Removed the old ram chips, added sockets and the new ram. When i turned it on again i just got a black screen. checked the psu voltage. Just over 5v. Also checked my solder joints and all good. Would love to get this working so any advice would be greatly appreciated. regards darren