Creating a Schematic from a PCB - What tools are available.

I have a desire to take a populated PCB, take a digital photo of the top and bottom, then import the images into a PCB layout tool. What would be ideal would be to lay components on top of the imported PCB image on a different layer, manually route these components (following the tracks from the image), then do a 'Forward Annotate' to create the schematic.

I cannot seem to find a PCB layout tool that will allow me to do this. The tools that I have found, which support forward annotation, will not allow complete components to be forward annotated. Many of the tools will allow the image import but not the level of forward annotation that I desire.

Does anyone know for sure a PCB/Schematic layout tool that will allow this? Thanks Jim

Reply to
Jim Flanagan
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In Altium for instance, you can't place an image on the PCB, only vector. You'd have to draw a crude representation elsewhere, e.g. PhotoShop, and paste it in. Knowing the images, and the outlines and traces and placements, you could then place and route. Altium does support back annotation (PCB to schematic, surely you meant this instead of forward?), but only on limited parameters; the schematic is a fixed construction, and the netlist is derived from it.

I haven't tried back annotation on the level of components and netlist in Multisim/Ultiboard, so I don't know if it supports such an operation. I do know Multisim is more fluid on its schematic representation, and may support something like this. Don't know if Ultiboard supports graphics on PCB.

The total amount of labor is about the same, what's wrong with copying the schematic directly off the PCB by hand?

Tim

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Website: http://webpages.charter.net/dawill/tmoranwms 
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Reply to
Tim Williams

No. What you're doing is reverse engineering the PCB. There are a substantial number of services that will do that for you. Most have built their own tool sets. Google for "reverse engineering PCB".

For example:

The general idea is to build a top view of the PCB showing only the components to form a "schematic" of sorts. Then, connect the traces between components from the PCB using a schematic capture program. When you think you have all the traces run from point to point, move the components around to where they would best be located in a schematic. The lines will "rubber band" and follow the components. Then, clean up the wiring mess. I reverse engineered the glow plug timer schematic in my former Dodge D50 diesel pickup truck this way. While the board was fairly simple (about 40 parts, 2 layers), it was also a learning experience for me in using KiCad:

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Jeff Liebermann     jeffl@cruzio.com 
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Reply to
Jeff Liebermann

I've always understood that if you have a Schem/PCB design in progress and a change is made after the fact to the schematic, then a 'back annotation' is made to the PCB. If the change is made directly to the PCB, then it is called a 'forward annotation'.

Of the tools that I have tested this has been true also.

I'll see if I can find a trial copy of this tool for testing.

The board is of sufficient complexity that I thought that doing it by hand maybe a bit much. However, I may not have a choice. I was hoping to make this effort less of a project in it's own.

thanks for your input... Jiim

Reply to
Jim Flanagan

Yes, I have a thermocouple meter device that has an issue and want to attempt a repair. Thus my desire for a schematic.

This is precisely what I want to do. Thanks for your input... Jim

Reply to
Jim Flanagan

You have it backwards. If the change is in the normal direction of process flow, it's "forward annotation". If the change counters the normal process flow, it's called "back annotation".

Reply to
krw

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