Where is the scope connected? Can you measure across the 5v connection and spread out the trace to see the ripple? When connected there you should a fairly square wave with no negative going pulse. The top part of the trace should hsve the ripple.
Sent from my iPhone > On Sep 3, 2025, at 00:24, Rob Jarratt <[email protected]> wrote: > > >> >> >> One other thing… >> With it powered on and measuring voltage at the outputs but not at the >> plugs, wiggle the plugs a bit and see if there wierdness with them. >> plugs and connectors go bad often and it doesn’t seem obvious that they do >> but saves a lot of time just by checking them now. >> >> Sent from my iPhone >> >>>> On Aug 31, 2025, at 13:34, Wayne S <[email protected]> wrote: >>> >>> Ps if you didn’t get continuity for a moment in one direction then the cap >>> is >> open. If you get continuity in both directions then it’s shorted. Hope this >> helps. >>> >>> >>> Sent from my iPhone >>> >>>> On Aug 31, 2025, at 13:28, Wayne S <[email protected]> wrote: >>>> >>>> Rob, replace c21 because of the bulge. If you want to check an >>>> electrolytic >> cap with a ohmmeter ,(kinda hard with a digital one), connect the meter >> across the ends. You should get either infinite resistance or a momentary >> reading of zero going back down to infinite resistance as the cap charges. >> Then reverse the leads and it should be infinite from the start. >>>> On an old analog meter with a dial, you can quickly tell by see the needle >> deflect full scale in one direction then settle back down to infinite. I >> keep an >> old meter around just for this purpose. >>>> > > > Replacing those caps seems to have fixed the issue, need to do a bit more > testing. However I am unsure about some spikes on the +5V output when I try > to check the ripple. > > This is the scope trace: > https://rjarratt.wordpress.com/wp-content/uploads/2025/09/5v-output-ripple-after-replacing-caps.png > > Does that look reasonable or should I try to work out where these spikes are > coming from? I replaced C21 and C35. > > Thanks > > Rob >
