Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems.

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Nelson
 
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Default Creating a Circuit Diagram from a PC Board

I don't know if anyone here has tried this before, but I thought I'd
mention it. I have found creating a circuit diagram from a PC board a
big PITA. Especially vexing is continually flipping the board over to
determine the connections. If you have ever tried, you know what I
mean.

Recently I found a way to make this problem a lot easier. First, take
a digital photo (close up, high resolution) of both sides of the board.
Then use an image editing program like Photoshop to flip the trace
side image to it's mirror image and remove everything but the traces
from the image. That's relatively easy because the board is all green
and the traces are all gray. Finally, paste that image as an "alpha
channel" with semi-transparency into the component side image.

The result is a full color "x-ray" of the PCB showing the traces and
solder joints directly under the components. It takes a little
experimentation to get the transparency and alignment of the two images
just right but the result is worth it.

--
Nelson

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Rheilly Phoull
 
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Default Creating a Circuit Diagram from a PC Board

Nelson wrote:
I don't know if anyone here has tried this before, but I thought I'd
mention it. I have found creating a circuit diagram from a PC board a
big PITA. Especially vexing is continually flipping the board over to
determine the connections. If you have ever tried, you know what I
mean.

Recently I found a way to make this problem a lot easier. First, take
a digital photo (close up, high resolution) of both sides of the
board. Then use an image editing program like Photoshop to flip the
trace side image to it's mirror image and remove everything but the
traces from the image. That's relatively easy because the board is
all green and the traces are all gray. Finally, paste that image as
an "alpha channel" with semi-transparency into the component side
image.

The result is a full color "x-ray" of the PCB showing the traces and
solder joints directly under the components. It takes a little
experimentation to get the transparency and alignment of the two
images just right but the result is worth it.


Then again a decent light underneath usually shows the traces.

--
Regards ......... Rheilly Phoull


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Default Creating a Circuit Diagram from a PC Board

A flatbed scanner instead of a camera might work better, consistent
scaling.

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Sam Goldwasser
 
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Default Creating a Circuit Diagram from a PC Board

"Rheilly Phoull" writes:

Nelson wrote:
I don't know if anyone here has tried this before, but I thought I'd
mention it. I have found creating a circuit diagram from a PC board a
big PITA. Especially vexing is continually flipping the board over to
determine the connections. If you have ever tried, you know what I
mean.

Recently I found a way to make this problem a lot easier. First, take
a digital photo (close up, high resolution) of both sides of the
board. Then use an image editing program like Photoshop to flip the
trace side image to it's mirror image and remove everything but the
traces from the image. That's relatively easy because the board is
all green and the traces are all gray. Finally, paste that image as
an "alpha channel" with semi-transparency into the component side
image.

The result is a full color "x-ray" of the PCB showing the traces and
solder joints directly under the components. It takes a little
experimentation to get the transparency and alignment of the two
images just right but the result is worth it.


Then again a decent light underneath usually shows the traces.


But not where they go behind parts.

Of course, that's still a problem for double sided and more of a problem
for multilayer PCBs.

But I like his general approach.

In fact, I may go and try it as I have a single sided PCB to trace at the
very moment.

--- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
+Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
| Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: Anything sent to the email address in the message header above is
ignored unless my full name AND either lasers or electronics is included in the
subject line. Or, you can contact me via the Feedback Form in the FAQs.
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Sam Goldwasser
 
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Default Creating a Circuit Diagram from a PC Board

writes:

A flatbed scanner instead of a camera might work better, consistent
scaling.


It will work great for the traces but may have problems depending on
how tall the tallest part is. Though, before I had a digital camera,
all the photographs of circuits boards in the FAQs were done on ab HP
scanner.

--- sam | Sci.Electronics.Repair FAQ:
http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
+Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
| Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: Anything sent to the email address in the message header above is
ignored unless my full name AND either lasers or electronics is included in the
subject line. Or, you can contact me via the Feedback Form in the FAQs.


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petrus bitbyter
 
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Default Creating a Circuit Diagram from a PC Board


"Nelson" schreef in bericht
.com...
I don't know if anyone here has tried this before, but I thought I'd
mention it. I have found creating a circuit diagram from a PC board a
big PITA. Especially vexing is continually flipping the board over to
determine the connections. If you have ever tried, you know what I
mean.

Recently I found a way to make this problem a lot easier. First, take
a digital photo (close up, high resolution) of both sides of the board.
Then use an image editing program like Photoshop to flip the trace
side image to it's mirror image and remove everything but the traces
from the image. That's relatively easy because the board is all green
and the traces are all gray. Finally, paste that image as an "alpha
channel" with semi-transparency into the component side image.

The result is a full color "x-ray" of the PCB showing the traces and
solder joints directly under the components. It takes a little
experimentation to get the transparency and alignment of the two images
just right but the result is worth it.

--
Nelson


Well... It's a way. I used a scanner to make the pictures. As most of the
times I cannot remove the components, I keep a mirrored full color picture
of the solder side next to the real thing. Of course, things became more
difficult over time as PCBs tend to be soldered on all sides these days.

petrus bitbyter


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Jeff Liebermann
 
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Default Creating a Circuit Diagram from a PC Board

hath wroth:

A flatbed scanner instead of a camera might work better, consistent
scaling.


It won't. A scanner has a very narrow depth of field. If there is
anything between the scanner glass plate and the board, it will cause
the board to be out of focus. I've tried it and it doesn't work.

I use a digital camera to take photos of both sides of a board. I
then use a photo editor to flip over, convert to a transparency, and
eventually create a composite image. If I'm ambitious, I play with
the colors sufficiently to remove the uniform board and trace colors,
leaving only the components. Then, it's easy to just connect the
dots.

If I'm really ambitious (or have lots of time), I import the component
layout BMP into a CAD or PCB layout program, overlay the components
with component symbols, overlay the connect the dot traces with rubber
bandable lines, and then drag the components into something resembling
a schematic. I recently did this with the glow plug control box for
my diesel truck, which was very simple. I don't recommend this method
on anything complicated.

A few years ago, I inherited a large pile of boards without
documentation. I wanted to get them working and had to generate a
schematic. It was tough because of the large number of SMT parts. So,
I sacrificed one board, used a propane torch to remove the components
(on both sides), and ended up with a bare board. Much easier than
trying to trace the board with the components in place.

Incidentally, there are companies on the internet that advertise
circuit board reverse engineering services. If this is a complex
board, you might want to get a quotation before attacking. For
example:
http://www.armtec.net/circuit_reverse_engineering.shtml
http://www.cadx-pcb.com/CADX_ReverseEngineering.html
(many more...)


--
Jeff Liebermann
150 Felker St #D
http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
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Nelson
 
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Default Creating a Circuit Diagram from a PC Board

Here are some links that show a sample board I did:

http://i68.photobucket.com/albums/i1...components.jpg
http://i68.photobucket.com/albums/i1...5/2_traces.jpg
http://i68.photobucket.com/albums/i1...races_mask.jpg
http://i68.photobucket.com/albums/i1..._composite.jpg

It's overkill for this board, I know, but it is a good example of the
technique. You can see how it wouldn't work with a scanner because of
the height of the components, particularly the heat sink. As it was, I
had to prop up one end when photographing the traces to keep it level.

--
Nelson

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Hamad bin Turki Salami
 
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Default Creating a Circuit Diagram from a PC Board

On Thu, 25 May 2006 05:11:12 -0700, rubenz1967 wrote:

A flatbed scanner instead of a camera might work better, consistent
scaling.


Isn't there a problem with static on a flatbed?

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Pooh Bear
 
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Default Creating a Circuit Diagram from a PC Board


Hamad bin Turki Salami wrote:

On Thu, 25 May 2006 05:11:12 -0700, rubenz1967 wrote:

A flatbed scanner instead of a camera might work better, consistent
scaling.


Isn't there a problem with static on a flatbed?


Why should there be a problem ?

Graham




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Sam Goldwasser
 
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Default Creating a Circuit Diagram from a PC Board

Jeff Liebermann writes:

Hamad bin Turki Salami hath
wroth:

On Thu, 25 May 2006 05:11:12 -0700, rubenz1967 wrote:

A flatbed scanner instead of a camera might work better, consistent
scaling.


Isn't there a problem with static on a flatbed?


No. Methinks you're thinking of a non-flatbed scanner such as one of
the multi-malfunction desktop printer/scanner/fax/modem/shredder
combinations. The ones with rubber rollers or sheet feeders might
create a static charge, but always have brushes at the paper exit
slots to remove the charge. Besides, I wouldn't want to run a
populated circuit board between the rollers anyway. Crunch.

Drivel: Long ago, one of my products was in the prototype stage when
marketeering decided to stop everything so that they could take some
pictures. The boards were carefully sent to a photographer, who took
numerous photographs under the bright studio lights. When I got the
boards back, they were all dead. All the (2716) EPROM's had been
partially erased. I don't think a flat bed scanner will do the same
thing, but I wouldn't want to find out.


The typical flatbed scanner just uses a bright fluorscent lamp so shouldn't
have any effect on erasable programmable parts.

I used to use an HP scanner for all the photos of reasonably planar circuit
boards in the FAQs and still do. The resolution and perfect geometry are
amazing for such inexpensive technology!

--- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
+Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
| Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: Anything sent to the email address in the message header above is
ignored unless my full name AND either lasers or electronics is included in the
subject line. Or, you can contact me via the Feedback Form in the FAQs.
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g. beat
 
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Default Creating a Circuit Diagram from a PC Board

"Nelson" wrote in message
.com...
I don't know if anyone here has tried this before, but I thought I'd
mention it. I have found creating a circuit diagram from a PC board a
big PITA. Especially vexing is continually flipping the board over to
determine the connections. If you have ever tried, you know what I
mean.

Recently I found a way to make this problem a lot easier. First, take
a digital photo (close up, high resolution) of both sides of the board.
Then use an image editing program like Photoshop to flip the trace
side image to it's mirror image and remove everything but the traces
from the image. That's relatively easy because the board is all green
and the traces are all gray. Finally, paste that image as an "alpha
channel" with semi-transparency into the component side image.

The result is a full color "x-ray" of the PCB showing the traces and
solder joints directly under the components. It takes a little
experimentation to get the transparency and alignment of the two images
just right but the result is worth it.

--
Nelson


Jim Garland had this same issue -- needing to create a circuit diagram from
a PC board.
He used CIRCAD - for the HRO-600 project.

His challenge was the very rare National HRO-600 receiver.
http://www.miami.muohio.edu/presiden...ers/hro600.htm

The details of his extensive investigations, repair and restoration
(including finding a long-discontinued Motorola IC of the "MECL II" family
for the repair)
http://www.miami.muohio.edu/presiden...storation.htmg. beat

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Jeff Liebermann
 
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Default Creating a Circuit Diagram from a PC Board

Hamad bin Turki Salami hath
wroth:

On Thu, 25 May 2006 05:11:12 -0700, rubenz1967 wrote:

A flatbed scanner instead of a camera might work better, consistent
scaling.


Isn't there a problem with static on a flatbed?


No. Methinks you're thinking of a non-flatbed scanner such as one of
the multi-malfunction desktop printer/scanner/fax/modem/shredder
combinations. The ones with rubber rollers or sheet feeders might
create a static charge, but always have brushes at the paper exit
slots to remove the charge. Besides, I wouldn't want to run a
populated circuit board between the rollers anyway. Crunch.

Drivel: Long ago, one of my products was in the prototype stage when
marketeering decided to stop everything so that they could take some
pictures. The boards were carefully sent to a photographer, who took
numerous photographs under the bright studio lights. When I got the
boards back, they were all dead. All the (2716) EPROM's had been
partially erased. I don't think a flat bed scanner will do the same
thing, but I wouldn't want to find out.

--
Jeff Liebermann
150 Felker St #D
http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
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Hamad bin Turki Salami
 
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Default Creating a Circuit Diagram from a PC Board

On Sat, 27 May 2006 08:26:34 -0700, Jeff Liebermann wrote:

Hamad bin Turki Salami hath
wroth:

On Thu, 25 May 2006 05:11:12 -0700, rubenz1967 wrote:


Drivel: Long ago, one of my products was in the prototype stage when
marketeering decided to stop everything so that they could take some
pictures. The boards were carefully sent to a photographer, who took
numerous photographs under the bright studio lights. When I got the
boards back, they were all dead. All the (2716) EPROM's had been
partially erased. I don't think a flat bed scanner will do the same
thing, but I wouldn't want to find out.


Going further afield ... this reminds me of the experience of a composer
I knew (actually well known, but I won't identify him). He landed a
performance of an extremely difficult opera he wrote. The technical
difficulty limited the possible performers to a very rarified set of
companies, and getting any performance of a modern opera at all is a major
coup for a composer. Of course, he had a recording done one of the
nights, and the performance was brilliant, beyond his hopes. The next
week, the engineer had the master tapes in his studio. While mucking
around for something, he placed a telephone on top of the tapes. As fate
would have it, that moment the telephone rang. It was one of those old
telephones with a big electromagnet driving the clapper of a bell ...
and that was the end of the recording of that brilliant performance.





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Neil Preston
 
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Default Creating a Circuit Diagram from a PC Board

I just recently went through this myself. Use the scanner to image the foil
side of the board, then mirror the image to make an x-ray view from the
component side. (My print dialog has this as an option.) Then using a red
pen, I draw the component symbols between the trace pads. Identify the DC
supply and ground traces, and use various color highlighters on them. When
done, it's fairly straightforward to draw the schematic of the circuit.

I've had moderate success scanning the component side of the board, too.
Seems many scanners have fairly good focus at 1-2" from the glass.

Neil



"Sam Goldwasser" wrote in message
...
writes:

A flatbed scanner instead of a camera might work better, consistent
scaling.


It will work great for the traces but may have problems depending on
how tall the tallest part is. Though, before I had a digital camera,
all the photographs of circuits boards in the FAQs were done on ab HP
scanner.

--- sam | Sci.Electronics.Repair FAQ:
http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
+Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
| Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: Anything sent to the email address in the message header above

is
ignored unless my full name AND either lasers or electronics is included

in the
subject line. Or, you can contact me via the Feedback Form in the FAQs.



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