MeanWell RT65B Issue

NuttyMonk · Joined: Jun 30, 2020 Posts: 62 Location: UK

Hi all,

i messed up with a circuit i built on some perfboard and didn't cut the traces underneath the IC socket. This created a short. I then went back over the circuit to find the problem, fixing the issues it had but then i noticed there was something wrong with my power supply. When i did a continuity test on the power supply there was continuity between the ground and 5V rails. Also when i turn it on there is continuity between the ground and -12V rail as well.

I've taken it apart but everything looks immaculate inside. Nothing looks damaged. I expected to find a component or two that had some heat damage or a burst cap or two but i can't find anything wrong with it at all.

Does anyone have any advice for me on how to go about finding the problem? I can't find schematics for this unit online.

Cheers

NM

DES · Posted: Sun Aug 28, 2022 6:05 pm Post subject:

I don't think there is a crowbar circuit in those...sometimes they can fail shorting the output to ground. Just as a sanity check - you did have the power supply disconnected from every thing before doing your continuity checks? Just in case it's something further down the line causing the short... Are you actually seeing zero ohoms or just zero volts? Look to see if there are any fuses that are blown...

There may be a FET or MOSFET that is keeping the circuits shut down. Without a schematic it's tough to say exactly where. You can always use the 'Easter Egg Hunt' method and just start testing compnonents in circuit and see which ones are showing shorts. Start from the output and work back.

It will take time unless you're lucky. Might be better to just buy a new one. Not sure what they cost in UK but I get them here from my local supplier for about $24. I don't know if they have any stock on them. I usually use seperate supplies for all the rails.

Did you try contacting Meanwell for schematics?

dave