Create design from layout and generate schematic?

Hello,

Trying to reverse engineer a power supply in order to fix it. One way would be to ‘copy’ the layout and then generate a schematic. Is this possible?

Many thanks for any suggestions!

Regards,
Staffan

Some variant of this question seems to come up on the Forum every couple of months. This week’s version is “Convert PCB file to schematic”

Your power supply wouldn’t happen to be a model “HUP45-30”, from XP Power, would it? I manually traced out that schematic a couple months ago.

KiCAD does NOT include any built-in way to create a netlist - much less a schematic - from a KiCAD layout. In general, it’s difficult to do it reliably with any automated tool. And, in your case, there’s the problem of getting from an completed board assembly to the PC board layout. Assuming it’s a two-layer board, you’re gonna spend a lot of time looking through a magnifier, gently prodding parts out of the way, and checking continuity with your multimeter just to get the layout into KiCAD. For that much effort you can just as well sketch the schematic without duplicating the layout.

Dale

P.S. - You might consider adding a few lines about yourself in your profile. It sometimes helps us compose an effective reply if we know who we’re talking to.

When you say ‘copy’, do you mean you have a design file already, in KiCAD format, or did you mean a literal copy like a scan or photo ?
I’ve heard the Chinese can reverse-engineer a board by imaging, but that involves stripping a provided board, and quite a bit of ‘manual assist’… not quite a ‘fix it’ pathway.

If you do have a PCB file, in the thread linked above is a link to my script PcbNew_Export_PcbNew_NET.py, which can export a netlist.
You can then use that to more easily check your manually sketched schematic.

In general terms anything is possible.

In power supply terms, presumably switching supply, you are about to enter hot waters.

Apart from that you just take a photo of the pcb under side flip it, scale it accordingly and import it as e.g. dwgs.user layer as a reference. You might want to change the opacity to have it sit faintly in the back.

A second photo of the top side on another layer is very helpful as well. You might want to temporarily desolder large obstructive components for a better top view.

As a side note. KiCad definitely needs more engineering layers.

Then you start in a new schematic to enter all the components as you find them on the board. You most likely will have to define some of those components (symbol, footprint etc.) explicitly since you are unlikely to find them in the included libraries.

Follow the tracks to establish connections. F8 to Pcbnew every now and then to place the components roughtly where they are in that background photo. Refine the design step by step as you build up the schematic.

Once you have build up a decent ratsnest you can begin to layout tracks, zones etc. that match the background photos more or less.

Keep going with lots of patients, and voila before you know it you are done.

If the original power supply is a two layer design, it is not too hard. If it is 4 or 6 layer it is much harder

Hello,

Many thanks to all taking the time replying!
I only have photos of the populated boards (it’s a power supply to a Wiltron Network Analyzer by the way) - and the boards themselves of course.
Will try to go from schematic and generate PCB so I know connections are right.

Regards,
Staffan