On Sun, Jul 30, 2017 at 5:18 PM, Jules Richardson via cctalk <cctalk@classiccmp.org> wrote: > On 07/30/2017 10:59 AM, Ian Frost via cctalk wrote: >> >> Any body any experience in fixing these old Acorn PSUs - or managed to >> source alternative modern supplies?
In general smoke from a power supply that keeps on working is from the mains filter capacitors. Some makes are well-known for this. I would carefully examine them, they crack when they fail There will be class X capacitors between live and neutral and class Y between live and earth and neutral and earth, The former are the ones that normally fail, but I would change the lot. > Unfortunately I did trace out some, possibly all, of that PSU (most likely, > it was certainly a VMS-something in my ACW) years ago, but even if I do > still have the schematics, they're on the other side of the Atlantic. The > PSU in mine had the rectifier diode on the +12V rail go intermittent, so it > would start sometimes and not others. > > Tony D. might have schematics, but I have a feeling they weren't part of the > ACW service manual as the PSU was bought in from an external supplier and > not an Acorn part. I certainly traced out the schematics of mine, but I forget which PSU was fitted to my machine (something tells me it was made by Farnell). I can try to find them. -tony
