i4000

I have had a good look around the board and cannot find any obvious shorts, solder splashes etc., I don't appear to have a C49 on my board which is a PAL C070067 REV B, from what I can see the board is basically a 130XE with the second bank of RAM and the MMU removed. The current DRAMs are a mixture of MT4164 & Sharp LH2164, from what I can see there has been no re-work on these so I guess it was what was knocking around the factory at the time of production. I have ordered myself up some Samsung DRAM as replacements. I will let you guys know how it goes. Thanks for the help and advice so far :)

Thanks TZJB, I'll go for the DRAM chips first then. Yes, I do have 16 DRAM spaces on my motherboard (8 unpopulated).

Thanks for the advice, any suggestions on reliable brands to go with, or is it just anything except MT?

Thanks for the suggestion StickJock, unfortunately it occurs with the keyboard disconnected

Hi all, I am a long-time lurker on the forums but decided to post today for the first time to ask for some advice. I have an issue with a 65XE that I am looking for a bit of advice with. I took my 65XE out of storage earlier this month, powered it on and all was fine, however I quickly noticed that (a) I had no audio and (b) I could not load anything from cassette. After a bit of digging around I found a few posts discussing C19 which is part of both the audio output channel and the SIO audio path. I whipped this out along with the adjacent C20 and tested them in an LCR tester and C19 was dead (complete open circuit, and no capacitance) and C20 was not far behind. So, I ordered a couple of NP electrolytics and replaced both of these. Unfortunately, after setting everything back up, my 65XE will now no longer boot into BASIC, it just boots direct into the memory test, completes the first line of dots (no reds) and then displays a blank green screen. A little bit annoying as, for a change, I had observed all ESD precautions when working on the PCB. I have done a bit of digging and from what I understand, if the machine boots direct into the memory test, then it indicates that a memory error has been detected during initialisation. None of the chips are socketed so I checked all the RAM chips and FREDDIE for dry soldered joints, corrected a few that looked a little 'suspect', but this made no difference. I tried checking for hot chips whilst the computer was powered on and I noticed that if I touch the FREDDIE chip even the slightest amount that the screen corrupts and the computer crashes, in fact it appears that you just need to bring your finger close to it for the screen to start flickering, I am not sure if this is normal. I re-flowed all FREDDIEs pins but no change. Unfortunately, I do not have access to an oscilloscope so cannot start checking signals. I am a little stumped what to do next, ultimately my intention is to upgrade the RAM, I haven't decided yet if this will be a 128KB, 320KB or 1MB expansion via the relevant methods, but I obviously need to get the base RAM working before I start anything. I was just on the verge of ordering a bunch of MT4264-15's, MMU, DIL sockets, and FREDDIE replacement but thought I would check here first before pressing the buy button. What do you guys think? Has anyone come across anything similar before? Am I in the right area?