Thanks Antonio, The location of the diode is arrowed on this picture: https://rjarratt.files.wordpress.com/2022/11/img_20221120_205802-arrowed.jpg
You can also see the heatsink where the transistor used to be. Regards Rob > -----Original Message----- > From: Antonio Carlini via cctalk <cctalk@classiccmp.org> > Sent: 20 November 2022 20:38 > To: Rob Jarratt via cctalk <cctalk@classiccmp.org> > Cc: Antonio Carlini <a.carl...@ntlworld.com> > Subject: [cctalk] Re: Identifying a Failed Diode in a Rainbow H7842 Power > Supply > > On 20/11/2022 17:40, Rob Jarratt via cctalk wrote: > > The H7842 PSU in my Rainbow failed yesterday. At first the machine > > just powered down and there was a slight burning smell, I wasn't next > > to the machine when this happened, so I didn't see or hear anything to > > tell me where the problem might be. Not being sure if there was a > > short in the machine or a problem in the PSU, I disconnected the fans, > > FDD and HDD and, probably foolishly, I applied power again to see if the > machine would work. > > At this point there was a bang and a flash in the PSU. > > > > > > > > > I blogged this here (it repeats most of that I have said above): > > https://robs-old-computers.com/2022/11/20/dec-rainbow-h7842-power- > supp > > ly-fai > > lure/ > > > > I have Rainbow PSUs H7842A, H78420 (which I suspect I may have misread! > ...) and H7842D available. I can look tomorrow; if you can supply an overview > picture and maybe circle the location of the offending parts that might help > me identify them more quickly (always assuming that they are marked at all, > of course). > > > Antonio > > > -- > Antonio Carlini > anto...@acarlini.com
