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Hi getting a 3400 up and running (240) lovely machine came with a 64MB ram expansion, recent few days it’s be raising an intermittent memory check error on start up and then only using 32MB. anyone have similar experience? wonder if it’s a broken solder connection or a mb connector issue? On...

Thanks I will, you too. So yeah the video is a tutorial on testing bridge rectifiers, my question was is it normal to get a reading on the two ac pins? I was getting .600ish in one configuration, see first two pics below. So as it happens the new rectifier turned up today and no, it’s not good...

Yeah appreciate that @techknight, not skilled at testing some of these more complicated components - hence the video, trying new parts is a way forward. Even with the schematic I'm not sure which components you're referring to, can you give me a reference at all? Hope it's not grenaded itself...

So following this guide on YouTube looks like the bridge rectifier D101is shorting - I understand from this that both middle ac pins shouldn’t give a reading but I’m getting .6 from pin 3(- lead) & 2(+ lead), can anyone confirm?

Replaced the diodes at 105 & 106 same issue, just starting to replace components now! Following this thread https://68kmla.org/bb/index.php?threads/macintosh-iisi-power-supply-diodes.32114/ I’ve ordered a STR80145, not sure how to test these so ordered replacement, probably D101 too. - any...

Hi Joshc, on pause for a few days, figured out how to test continuity on those traces, all seems good. Ordered some diodes and a couple of thermistors will re-flow those joints at the same time and see. Watching videos on repairing switching PSUs!

TH101 was blown apart! have replaced, diodes read ok and resistors check out - and still blowing fuse, some corrosion on the board from around D301 C302 see picture, maybe from leaky cap previously could this cause short?

Yes Sony, thanks Joshc something to get started with, much appreciated

Recapped the power supply and main board a couple of years ago and all working well, not used for 6months or so went to boot up last week and there was a pop from the psu, I’ve taken it apart and had a clean round no obvious faults, replaced fuse and pop again, any ideas or advice on where to...