How to reverse engineer a simple through-hole board

[victor]

Just scanned something quickly to show how bad it turns out, but I know that some scanners do it pretty well


So in that case a camera gives better results, even with a bad iPhone 3GS camera


In sun light

[Mechatrommer]

Mount your camera on a tripod, if you have one, and point it straight down at the table. Put a piece of paper down on the table, and put the board on top of the paper. Trace the shape of the board onto the paper. Now make sure the board is lined up (this works well with square/rectangular boards, obviously) and take your first picture. Now flip the board, line up with the trace, and take picture #2.

theoritically and ideally speaking... use the greatest focal length you have. anything greater than 50mm (eqv focal length to full size sensor) is acceptable, the greater the closer it is to ideal. to avoid perpective distortion to bigger bulging components. no offense but the tracing you mentioned is an extra and unnecessary work. any photo editor with "scale and distort" feature can align easily. just as in the OP procedure.

i usually put a round brush or contrasty color on each corner, for each layer and make the alignment as in the OP, please note the green blobs in picture below, they are actually overlapped between bottom and top layer. it not only work for simple and square board. but also work with more complicated pcb shapes and bulgy components on each side that is hard to trace on paper.

[PA4TIM]

Something I do a lot: with complex repairs/alignments. I make a picture of the pcb and scan the page from the manual . Much more easy to find adjustment , measure points or components.


This is the drawing from the tek manual projected over a picture of the board. (not the best one but the most are full resolution so not handy  to show.
But the trick the TS does is indeed handy, I heard it from a friend and used it a few years ago for the first time while reparing a HP  5326

[pickle9000]

That is very nice PA4TIM! if you have it of course. 

[envisionelec]

Ah - one of my (many) tricks to reverse engineering. I also use an electron microscope for multilayer boards. It helps to know the owner.

An electron microscope doesn't damage some chips? I never used one or had access to one.

I don't scan board with parts on them. Never tried that, but I can only assume damage.

I don't own the SEM - it belongs to the company for which I work.

[jahonen]

Ah - one of my (many) tricks to reverse engineering. I also use an electron microscope for multilayer boards. It helps to know the owner.

An electron microscope doesn't damage some chips? I never used one or had access to one.

I don't scan board with parts on them. Never tried that, but I can only assume damage.

I don't own the SEM - it belongs to the company for which I work.

I have always thought that SEM can only "see" surface structures due to the principle and even thin coating blocks the view. Can you elaborate how you can look inside with it?

Regards,
Janne

[dds]

"Import then to a blank canvas on your favorite editing program. I'm using Adobe Fireworks,  you photoshop or almost any image editing software. The images must be in separated layers"

How to put images in separated layers in GIMP? Have no money for fancy Adobe products,  and I'm pretty inexperienced in picture editing

Thanks for any help!

 

[redben]

Hi nice tutorial.
Just to satisfy my curiosity.
What is the board in the example used for ?
Thanks to share your knowleges with us 

[Legit-Design]

"Import then to a blank canvas on your favorite editing program. I'm using Adobe Fireworks,  you photoshop or almost any image editing software. The images must be in separated layers"
How to put images in separated layers in GIMP?

File -> Open as Layers...    Ctrl+Alt+O

First you need to download gimp and install it.

[ablacon64]

How to put images in separated layers in GIMP? Have no money for fancy Adobe products,  and I'm pretty inexperienced in picture editing

Question answered by Legit-Design. Just a comment, it's not the cost that makes a good software, Gimp is a very powerful and fully featured image editing software. as good as photoshop is. You just need to learn how to use it. Like Photoshop, it has lots of advanced features to be mastered.

[dds]

"Import then to a blank canvas on your favorite editing program. I'm using Adobe Fireworks,  you photoshop or almost any image editing software. The images must be in separated layers"
How to put images in separated layers in GIMP?

File -> Open as Layers...    Ctrl+Alt+O

First you need to download gimp and install it.

Thanks for the tip. I've installed GIMP and tried it. But I'am again stuck in point 7 of tutorial:

7. "The 2 images are not in the same size, or angle. So we will use the Distortion tool to resize and straighten the corners of the top side so it match the bottom side"

What's equivalent for 'Distortion tool' in GIMP? I've found this manual page: http://docs.gimp.org/2.4/en/filters-distort.html  and there's menu Filters --> Distorts, but I'm bit confused  what and how to do this in GIMP

Thanks for any help.

[Legit-Design]

Thanks for the tip. I've installed GIMP and tried it. But I'am again stuck in point 7 of tutorial:
7. "The 2 images are not in the same size, or angle. So we will use the Distortion tool to resize and straighten the corners of the top side so it match the bottom side"

Tools -> Transform tools -> pick your tool

No need to do everything by the book, I here by give you the right to improvise. 

[victor]

Hi nice tutorial.
Just to satisfy my curiosity.
What is the board in the example used for ?
Thanks to share your knowleges with us 

It's used on a ancient inversor to generate a square wave, actually is a pretty bad design (not mine).

Thanks for the tip. I've installed GIMP and tried it. But I'am again stuck in point 7 of tutorial:
7. "The 2 images are not in the same size, or angle. So we will use the Distortion tool to resize and straighten the corners of the top side so it match the bottom side"

Tools -> Transform tools -> pick your tool

No need to do everything by the book, I here by give you the right to improvise. 

I'm not familiar with GIMP but I'm pretty sure it can be done.
as I said on the first post, some things will be slightly different on other softwares.

 "The adjustments are subjective and will depend on your board color, illumination, exposure, etc... there are many variables, play around and find what values works best for you."

[victor]

http://extrazoom.com/image-35217.html

[dom0]

When I was a lad (actually not a lad at the time) we used a flatbed scanner on a board component side down with a 200 watt incandescent above. The flatbed we had kept in focus up to almost 2 cm which covered most stuff. Cameras at the just didn't have the resolution. The beauty was you could see through most boards and the scanner light was bright enough to illuminate the components. No not perfect but this was a number of years ago.

Yeah I'm doing this for a long time, I used to have a old flat bed scanner, those with fluorescent light and it was able to focus like 1~3 cm above the glass, but I can't with my actual scanner.

Flatbed CCD vs flatbed CIS. CIS ones are cheaper and have about 1 mm of focus depth. Those with a CCD line usually have 2-4 cm focus depth.

[victor]

CCD Scanners have actual optics inside then instead of just a blob of acrylic that they call contact lens somethin-something.

Nowadays digital cameras are more accessible than ccd flatbeds

[albert22]

Victor, nice work. Thank you for the post!
As a contribution here is what I posted in another thread:

...
For me one key point in rev eng. is to assign component names to everything on board. If there is not a silkscreen or it is incomplete. I do that by taking a photo of the board and then tracing the outline of each component using powerpoint. This is not very tedious because you can copy and paste the outlines of similar components. Then I print only the outlines to have a clean layout of the board. Where I can assign names with a pencil to correlate them to the schematic.
...
I use powerpoint because it is very simple and it is installed in most of the PC that I use. BTW OpenOffice would do it too. With the photo on the background, my outlines are very crude, just rectangles circles and ellipses.  Once I get the printout I continue using only pencil and lots of paper.
I also used photocopies years ago when there were no digital cameras or scanners. Punctured the photocopy at each pin and then sketched the components by hand on the other side of the paper.

[ez24]

To Victor

I like the original post's layout.  I think it is better than attaching pictures via the "options".  Did you do it with html?  I saw that one picture is posted at

"i.stack.imgur.com"

I really liked the animation.  Was it a gif?

Since no one has complained about linking in pictures from another site, I would like to learn how.   Maybe this is common on this forum but yours is the first I have seen.

If html can you show (if possible) a few lines of code to link in a photo to get me started.

thanks

[victor]

To Victor

I like the original post's layout.  I think it is better than attaching pictures via the "options".  Did you do it with html?  I saw that one picture is posted at

"i.stack.imgur.com"

I really liked the animation.  Was it a gif?

Since no one has complained about linking in pictures from another site, I would like to learn how.   Maybe this is common on this forum but yours is the first I have seen.

If html can you show (if possible) a few lines of code to link in a photo to get me started.

thanks

Most forums I participated don't allow html, just BB code.

to attach pictures I host the pictures on a image hosting service like imgur

Code: [Select]

[img]http://i.stack.imgur.com/uRkHO.jpg[/img]
to limit it to the max width of the forum for large images.

Code: [Select]

[img width=700]http://i.stack.imgur.com/uRkHO.jpg[/img]

for clickable pictures

Code: [Select]

[url=http://linkofthefullpicture][img]http://thumbnail.jpg[/img][/url]
The animation I used the same software (Adobe Fireworks) to combine multiple screenshots into a GIF.

Attachments are good, only if you could inline then in the post would be great, and you can't view then when not logged on most forums.

[ez24]

thanks