BY127's I have plenty of.. 
I do also have a +2A PSU, but that's at the back of the barn behind all the boxes of components, laptops, other computers, valves, etc.!!! Also have a smaller 'laptop charger' size multivoltage thing, will have to see what the current rating is, that might do OK. 
Standby alert 
4116 RAM chips), and +12V (for same, and video encoder). Where's a 9V in there? Or am I missing something here? (Spectrum 128K / +2 / +3 machines?)
. the transistor failed and replacements failed instantly at switch on...I had to replace the oscillator transformer to cure it as it appeared to have been damaged - overheated? - there was certainly a whiff coming from it - when the original transistor went short circuit...I was very lucky to be able to get a replacement as this was some years after the 128 was current and the local TV/video repair shops supplier still listed them! ! What voltage checks I've been able to do)quickly) indicate the +5v and -5v line ok, but the +12v line low, I think either one or more 4116's drawing heavy current, or the LM1889 colour encoder doing the same, although I do get up a picture of sorts with coloured blocks all over, so that's probably ok! I know 78xx's are pretty cheap but I was trying to use what I've already got lurking around, without having to buy anything if I can help it !(got a few spare new-old-stock 4116's luckily - hope they're ok... !) Yes, very likely a problem with the lower RAM, one of those 4116 chips (as so often with ZX Spectrumsgozzo wrote:although I do get up a picture of sorts with coloured blocks all over, so that's probably ok!
). You could try feeling if one gets hotter than the rest, or (with board powered off) some resistance measurements between D and Q pins, and GND / 5V supplies (wouldn't know exactly which, try various pin combo's). Maybe there's one chip that deviates noticably from what you get for the other IC's.
