Author Topic: PCB Reverse-Engineering  (Read 47861 times)

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Offline Singapura

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PCB Reverse-Engineering
« on: March 30, 2015, 10:51:16 am »
Ever heard or tried reverse-engineering printed circuit boards without schematic diagrams?

You might want to take a look at the following website for more information or tips:

http://visio-for-engineers.blogspot.sg/
« Last Edit: March 22, 2017, 02:53:59 am by Singapura »
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Offline Bloch

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Re: PCB Reverse-Engineering
« Reply #1 on: March 30, 2015, 06:07:21 pm »

First this is more an AD page than blog.

That is this book ?


>PCB Reverse-Engineering


Why are some thing on transistors and DOS ?


Show us some pages there you are teaching PCB reverse engineering
 

Offline Singapura

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Re: PCB Reverse-Engineering
« Reply #2 on: April 01, 2015, 03:02:26 am »
Hi Bloch

Thanks for replying. Sorry that my blog appears to you as an AD.
There are stuffs that I shared in my blog which I'm currently backdating from when I started journaling and organizing them into a book.
If you click on the April and May 2014 archives, or under the Categories section, these should bring you to the pages containing useful information and illustrations.

Thanks for visiting and giving your feedback.
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Offline Singapura

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Re: PCB Reverse-Engineering
« Reply #3 on: April 01, 2015, 04:22:27 am »
By the way, the sample preview pages on my book in Amazon are not within my control.

As for the DOS stuff mentioned in one of the appendices, it's with regard to creating a DOS environment (DOSBox or Microsoft Virtual PC) in order to run a free DOS program that decodes JEDEC fuse map files into Boolean equations, if you're wondering...

Hope that clears up a bit on your questions. Thank you.
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Online Fraser

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Re: PCB Reverse-Engineering
« Reply #4 on: April 01, 2015, 08:52:09 am »
@Singapura

Welcome to the EEVBlog  :)

I do quite a lot of PCB reverse engineering out of necessity as so many manufacturers refuse to release schematic diagrams due to IPR concerns. I was working on a very expensive thermal camera a couple of years ago. It used a MC68340 micro processor that I was not familiar with. I ended up reverse engineering the whole embedded computer PCB and bought an ATARI 520ST (MC68000) on which to practice diagnostic techniques ! The thermal camera was basically an ATARI ST configuration with some additional I/O and a co-processor  :)  That was a very difficult reverse engineering task as the PCB was quite complex and there were many hidden interconnections within the layers.

The cameras PCB was 6 layers and populated with a mixture of VLSI, FPGA and common 74ALS series chips. On another PCB (video processing co-processor) I had to contend with three 250+ pin fine pitch FPGA's :(

As you know, creating a BoM was one of the first steps and fortunately for me the camera used commercial off the shelf components with no custom chips, unlike many specialist test equipment like that of HP and Tek. The data sheets were of great assistance as the camera manufacturer tended to follow the application note design..... always nice to see as it helps to speed up the reverse engineering process.

I used a clever piece of equipment from Wavetek to assist in finding the interconnections through continuity. It is called the Wavetek  SF10  and it uses a stainless steel brush for identifying the area of a connection and then a sharp point to localise it to a specific IC pin. A very useful bit of kit IMHO.

I posted about it here:

https://www.eevblog.com/forum/testgear/wavetek-sf10-short-finder-a-very-useful-tool-if-you-can-find-it/

I use the following equipment when reverse engineering a multi layer PCB:

1. Fluke 87III multimeter with fast continuity response
2. Wavetek SF10
3. Toneohm 850 inductive short tracer and MilliOhm meter
4. Non contact cable tracer and injector
5. Opti-Visor magnifier headset
6. Video Microscope
7. Light panel (to illuminate PCB)
8. Torch for detailed PCB inspection
9. X-Ray (high resolution imaging of PCB)
10. Thermal imaging camera
11. Mk1 eyeball  ;D
12. A lot of time  :-DD

And of course a PC with access to the WWW for chip research and documentation of the reverse engineering process.

I like the fact that you have taken the trouble to detail PCB reverse engineering techniques in a book and hope it does well for you. Would there be the possibility of an EEVBlog discounted edition as the membership here would make an excellent study group.

I attach a (low res) picture of the thermal camera microprocessor PCB that I reverse engineered. The schematic diagram is covered by ITAR and so is unavailable for public release.

Aurora
« Last Edit: April 01, 2015, 09:34:21 am by Aurora »
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Offline Singapura

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Re: PCB Reverse-Engineering
« Reply #5 on: April 01, 2015, 01:19:26 pm »
Hi Aurora

Thanks for your hospitality and nice gesture.

I'm impressed with the array of equipment and accessories you have to help you in the reverse engineering work! Given the complexity of the PCBs you work on, there is no doubt that any additional equipment that helps to speed up and ease the process is a great asset to have. Unfortunately, not every engineer has the luxury of owning these invaluable tools, much less to even attempt the kind of board you're dealing with.

I have done quite a fair bit of reverse engineering on boards as varied as you, as well as whole unit comprising multiple PCBs encased. It's challenging yet gratifying at the same time, and it always give a sense of satisfaction and achievement when it's completed, despite the grilling process we subject ourselves too, isn't it? Sometimes my colleagues would look at my work, shake their heads and give me the kind of look, like you know, you're one crazy guy to even consider this option.

Anyway, after 15 years of doing PCB reverse engineering (besides my primary job scope of test program development and engineering solutions support, including re-hosting of legacy systems for customers and building custom test jigs and text benches), I thought it'll be good if I can document my experience which is why I ended with the book. However, in writing it I did consider the common equipment that most electronic and repair engineers possess as well as the basic skills that'll enable them to have a good start in this demanding discipline. For your case, I do not foresee that my book will serve to advance your skill or knowledge in a big way. However, if you intend to use my book as a guide or reference to aid you in documenting your own experience, and hopefully to write your own on this subject, possibly as an advanced version, then I suppose it might help cut down a lot of preparation work and time.

The pricing of my book was a bit high, unfortunately higher than what I'd like it to be, primarily because it's full-color and uses a better grade paper which CreateSpace charged a premium, and being a non-US resident from a country without tax treaty with US, I am subjected to double taxation. But I am considering an electronic book (ebook) version which Amazon distributes via the Kindle channel, so if there is enough interest for a non-print version, I might just take it up. The pricing will most certainly be much lower than the printed one. Let me warn you that due to the large amount of photos and illustrations (300dpi) the size of the file will be huge (in excess of 50MB).

Once again, it's a pleasure to meet you and to know there are like-minded engineers doing this seemingly impossible but important task.

Cheers!
Singapura
« Last Edit: March 30, 2017, 05:48:24 am by Singapura »
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Online Fraser

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Re: PCB Reverse-Engineering
« Reply #6 on: April 01, 2015, 03:32:11 pm »
Hi Singapura,

Great to hear your story on the book.

My father looked into publishing a book last year and, like yourself, found it to be a very expensive exercise when paper format is chosen. I applaud your determination to continue through to a final paper based release.

eBook format would likely make the book far more accessible and affordable for many users BUT you have the issue of piracy to consider. sad though it is, there are many who will steal your book rather than pay you a fair sum for your efforts. eBooks make this a very easy theft unless you employ appropriate protection in some form. I am not enlightened on how an eBook is protected but presume there are ways that it may be done. For info, an eBook would be my first choice if it lowered the cost of ownership as I just retired  ;) With regard to file size, 50MB is not unmanageable in many countries these days. My Logic analyser software that I updated last night was 70MB in size. In this age of downloading films across the internet, file sizes have increased greatly and in many countries fast broadband makes them a relatively quick download event.

With regard to my reverse engineering capabilities, like yourself, I have been forced to teach myself and work out how best to approach the problems that are inevitable when undertaking such a challenge.  I enjoy repairing equipment and reverse engineering designs as they are like a puzzle that needs to be solved....some people do crosswords and SUDOKU to challenge their mind, I do electronics repair and investigation  ;D

With regard to the sample case that I mentioned, namely the thermal camera, I had a great incentive to succeed in reverse engineering the PCB. The camera is an AGEMA (FLIR) PM570 and it was new in its case. It had been found faulty when a warehouse was cleared and was likely a customer return. I paid £1000 for it but its original cost was $56000 from FLIR  :scared:  As it was mint, I was determined to repair it and keep it for myself rather than attempt to sell it on for profit. When you want to repair something for yourself I feel there is even greater motivation to succeed  :) 

Some background on the FLIR PM570 thermal camera.... this was the first FLIR uncooled Microbolometer thermal imaging camera to market and was a flagship model. It is built to last and put up with abuse. A truly superb design that has become a firm favourite in industry. It has a 320x240 resolution and 60fps refresh making it suitable for all manner of civilian and non-civilian uses. The camera was so popular that it was upgraded with faster processors and better microbolometers throughout the long PM series 'reign' I own examples of all generations (1 through 3). 

When I first opened the camera I was pleasantly surprised by its well designed clamshell format that positioned the two main boards in opposite halves of the case, with flexible ribbons between. Unlike some designs you did not end up with a pile of PCB's falling out on the bench when the case was opened ! Initial impressions of the PCB's was Oh Dear, high levels of integration and custom VLSI. I was, however, wrong. The unit contains two independent computers. One for the whole system management and one for the image processing required to tame a microbolometer. Both PCBs were in fact populated with the common commercial products of Motorola, Altera and Cypress and not custom VLSI. The overall system management board appeared the likely cause for the fault which was 'Failure to boot'. 

I contacted every FLIR service agent that spoke English in an attempt to gain any information on the AGEMA/FLIR thermal camera inner workings and boot sequence. All were sworn to secrecy under FLIR NDA's and ITAR restrictions on design information release. I found one who was willing to give me a tiny bit of help and some price quotes for parts. He advised that the problem was either the power supply module or the  LiCO board (MC68340 based system control). This sounded plausible. The LiCo was most likely and would cost £5000 + fitting + programming the OS into flash + camera calibration (essential as cal data resides on this board) The total cost.... likely to be around £7000  :o
As the engineer said..."you buy a Mercedes, you pay Mercedes spares prices". The engineer was not allowed to supply me with ANY technical details, not even the expected voltages coming out of the power supply module ! He did talk to me in general terms though, which is more than I can say for all the other service agents around the world. He explained that the service centres just identify and replace PCB's, then do calibration. They do no component level repair and I doubt that the chap even had schematics beyond PCB interconnection diagrams and voltage / waveform test points for diagnostics.

So with regard to repairing the faulty LiCo board, I was definitely on my own. As I stated, I created a BoM and tracked down the datasheets for every chip used on the LiCo. I had not worked on a MC68000 based computer before but knew the normal basic tests that may be carried out on any embedded computer. I did the usual checks on power supplies, clocks, address & data busses, and specific control/flag lines. The MC68340 was in HALT due to a critical error and that was all that could be determined.

I bought books on MC68000 series embedded computer design and studied its operation and design principles. Its a pretty smart processor and the MC68340 is just a MC68000 with some addons for interfacing to the outside world and memory. After thoroughly studying MC68000 architecture I purchased an old Atari520 ST to on which to practice logic analyser based diagnostics. It was very easy to create a HALT condition  ;D In truth I did not really need the ATARI computer as I was also cutting my teeth on the LiCo board to see exactly what was happening where and when. I had the full service manual for the ATARI 520ST though and that was helpful. It became clear that I needed to reverse engineer the whole LiCo PCB as there were many possible causes of the HALT condition. A key pint to note is that the LiCo board would not work unless all other boards were connected to it (an important point that will be explained later)

I started reverse engineering the LiCo PCB by first placing the board on a photocopier and enlarging the image onto A3 paper. This gave me an excellent view of the PCB component identifiers and also visible tracks. It was a 6 layer PCB though  :(

My colleagues at work saw my A3 images and when told what I was intending to do, said, "you are mad....just give up on it and chuck the camera in the bin" ! Such a negative attitude  >:(  I had an advantage over them though.... many years of component level repair experience. They just saw a PCB packed with tiny components, I saw a PCB with many interconnected blocks that interact and form a sort of code that just needs to be unravelled. Nothing to be scared of. You just need to deal with it logically and in small sections to prevent yourself becoming overwhelmed  :)

I had lots of the large A3 images so that I could scribble notes on them etc. Very handy.
For me the next step was to take all of the knowledge that I had gained from the datasheets, application notes, books on MC68000 computer architecture and the Atari 520ST schematics to connect all the various chips together in my own configuration, guided by logic. It isn't that hard as thankfully computers normally contain the same basic elements and have similar needs in order to work. I will not bore the readership by detailing all of them. I ended up with a block diagram/schematic that had all of the chips on the LiCo board interconnected in a logical manner that would form a viable computer.

It was then just a case of using simple tools to confirm expected interconnections between chip pins, and where the expected interconnection did not exist, finding where it went instead. That may sound easy but it is not when you are dealing with FPGA's. They act as Glue logic connecting many different ICs together in a unique fashion. Much time was spent working out which chips were servicing, and being serviced by, the FPGA's. The Wavetek SF10 was invaluable in this exercise as I could quickly work out which FPGA was involved with a chip pin that I was investigating. It did still take many evenings of work under the magnifying glass though !

I ended up with an accurate schematic of the IC interconnections and overall block diagram of the whole LiCo board  8) Once seen in this format it was not daunting at all and I restarted my investigation into the failure to boot.

Now the killer blow..... I could find no reason for the LiCo board to not boot. I even fitted new SMD DRAM just in case it was some weird RAM issue. No, still no boot. Now remember I mentioned that the LiCo would not work unless all other boards were connected to it ? There is a good reason for that. The LiCo effectively checks that all boards are present and operational as a sort of limited initial self test. Well what was actually happening was that the LiCo was not receiving a correct response from the other computer board and so it went into critical failure (HALT) mode and stopped the Boot sequence before it got properly started. The MC68340 would attempt a restart but fail on HALT. I had been chasing a fault on the wrong PCB  :palm:

In my defence, as I had no access to technical info on the start sequence or camera firmware, I was not to know that the MC68340 was checking on the other computer and expecting an 'OK' response. As far as I was concerned the MC68340 would boot and report any issues with its video processor board. That was not the case at all.

SOOOOOOO back to square one..... an embedded computer that fails to boot, but this time it was the video processor and not the LiCo ..... more reverse engineering  :'(

Fortunately the video processing board is nowhere near as densely populated as the LiCo. It is a dedicated image processing unit so has a relatively simple architecture. The bad news was that it contained three huge >250 pin FPGA's  :scared:  Each was programmed at boot but could in itself prevent correct boot, that would HALT the LiCo board ! There were also some key communication and data lines running between the LiCo computer and the video processor. Each needed to be identified and its ability to cause a HALT condition assessed.

Long story cut very short, I reverse engineered the video processing Board with little difficulty as it was a basic embedded computer design, just with specialist I/O. It has its own SRAM and Flash ROM so is independant of the LiCo for booting purposes. It was not booting because a 74ALS244 buffer that sits between the CPU and one of the FPGA's had a failed gate. The FPGA's were not being programmed and the CPU was stuck.

A new $0.50 74ALS244 was fitted and the $56000 camera was fully operational  :phew:

This task took many weeks and much dedication as I was doing it in brief sessions after work in my evenings. It would have been far better to dedicate a decent period of uninterupted time to the task as the human mind can tune into the design and not need to 're-learn' it after a break.

All good fun and I got a real thrill out of getting the camera to boot correctly after a long period of fault induced sleep. She's a beauty and I shall be keeping her.

I attach some pictures of another of my cameras... the PM575 which looks the same as the 570 in all but colour (the 570 is black). The open case images are from a PM695 that I was working on. Note the clam shell design and flexible interconnects between sides.

As you can see, I like my hobby  ;D

Best Wishes

Aurora

« Last Edit: April 01, 2015, 05:41:01 pm by Aurora »
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Offline Singapura

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Re: PCB Reverse-Engineering
« Reply #7 on: April 02, 2015, 02:28:38 am »
Hi Aurora

Thanks for your compliment, encouragement and great sharing on your exploit on the FLIR thermal camera adventure. It's always refreshing to read and feel the experience of someone who shared the same passion as myself. I couldn't agree more with you that PCB reverse engineering is like doing jigsaw puzzle and as the schematic diagrams begin to take shape, the greater the excitement and gratification, which is why I liken it to an art, one in which only those who put their mind and heart into can really appreciate and derive satisfaction.

From what I can tell through your narration of your attempt on the FLIR PM570, you certainly know your craft as an electronic engineer and will go to great lengths to finish what you set out to do, which is an essential trait for anyone who's thinking about taking up PCB reverse engineering. I reckoned I might have taken almost the same steps you did apart from buying the Atari 520 ST and creating those large A3 size images of the internal PCBs. I prefer to use Visio to create those PCB artwork to facilitate creating of BOM and collecting the necessary datasheets as a preliminary preparatory task. I believe by going through such exercises, I will become more acquainted with the PCBs I am working on.

Attached are some artwork of one of the units I worked on, the first is a front view with the panel cover removed, the second is the rear view with the connector slots in which the PCBs are plugged into, and the third is the layout diagram of the solder side of one of the PCBs, which is showcased in my book under advanced topics where I discuss about using Visio's layering technique.

I can identify with your enthusiasm and love for electronics, which has become your life-long learning and hobby. Kudos to your dad to for his desire to write a book. Perhaps after you get hold of a copy of my book, it might rekindle the fire in him to start the exciting journey, who knows?

Singapura
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Offline Singapura

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Re: PCB Reverse-Engineering
« Reply #8 on: April 02, 2015, 02:36:50 am »
By the way, what you said about the risk of distributing ebook is also my main concern, which is why I decided on printed book in the first place. I will have to check with CreateSpace and some other regarding ebook piracy issues before I decide if I want to go ahead with it.

Thanks for highlighting it as a good reminder. Much appreciated!  :)
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Online Fraser

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Re: PCB Reverse-Engineering
« Reply #9 on: April 02, 2015, 11:26:00 am »
@Singapura,

Totally agree on the Atari. It was an unnecessary step that was driven by my desire to test a new 32 channel logic analyser on a working MC68000 based computer. In all honesty it added little to the investigation in the end. I mentioned it because I sometimes think outside the box, exploring possible aids to understanding a designs operation. The Atari was really just a physical version of what I has read in the reference books.

The photocopy of the PCB is a technique I have used a lot as it is fast and aids my less than perfect eyesight when wishing to have an overview of the PCB. It also allows me to mark IC pins as they are traced or to highlight pins that are of specific interest. I have also used the large i.mages the create hand drawn PCB component layout diagrams. Your Vision approach to creating the drawings is far more sophisticated and an approach that I will try. I already have Visio loaded on my main PC as I use it for block diagrams.

Best Wishes

Fraser
« Last Edit: April 02, 2015, 05:55:16 pm by Aurora »
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Offline mikeselectricstuff

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Re: PCB Reverse-Engineering
« Reply #10 on: April 02, 2015, 11:38:33 am »
Quote
A new $0.50 74ALS244 was fitted and the $56000 camera was fully operational
One important lesson for both repair and reverse engineering - First try the things that are easy to try first, even if they aren't very probable faults.
Where there are very simple devices like HCMOS, it can be worth spending a little time running round all the pins with a scope to see if the signals make sense.
Ditto simple analogue parts like opamps.

Quite often when digital chips fail, their outputs or inputs will show intermediate voltages between rails, and can be easy to spot on a scope. Similarly opamp outputs will tend to hit rails if things aren't right.
« Last Edit: April 02, 2015, 11:45:44 am by mikeselectricstuff »
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Online Fraser

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Re: PCB Reverse-Engineering
« Reply #11 on: April 02, 2015, 06:04:37 pm »
@mike
Good advice indeed. In my case it was less simple though. The buffer chips had a failed input that was fed from one of the monster FPGA chips. I was unable to predict what what should be happening on that pin and it stayed low. The FPGA was actually unprogrammed due to the fault so was very unpredictable anyway. The fault was an input on the buffer that was low at all times. I could have used a pulser on the pins to stimulate some activity but with an FPGA connected to the pins I was a little cautious. This was a learning experience on these cameras and I now know them well so all the effort was not in vain. You are totally right about checking the easy bits first though. I have even resorted to changing chips without testing them if it is faster and safer than proding around a circuit looking for errors. DRAM would be a typical case where I might do such.

I must say I like the topic of this thread. I am not sure that reverse engineering has been discussed in much detail before ?
« Last Edit: April 02, 2015, 10:29:31 pm by Aurora »
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Online Fraser

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Re: PCB Reverse-Engineering
« Reply #12 on: April 02, 2015, 11:10:50 pm »
@Singapura,

I have just ordered your book through Amazon.co.uk and look forward to receiving it in due course. I feel sure that I will learn from your experience and look forward to seeing how you are using Visio. Thanks for putting the effort into authoring such a book and I hope it is very successful.

Whilst talking of reverse engineering PCB's I thought I would tell you my nightmare scenarios when attempting to do such.

I have opened up sophisticated equipment and found the PCB has been sanitised. By sanitised I mean that either it has been covered in opaque varnish coating or worse still, all of the important IC identification details have been ground off or laser erased  :( When I see this, my heart sinks. I am left to work out or guess what the IC is and its purpose before even starting the search for suitable candidates. This seems common practice on some Chinese equipment and the teardowns of DSO's on this forum provide plenty of examples. Fortunately an oscilloscope is a well understood topology and the architecture of many Chinese DSO's is similar. As such I always hunt for data or PCB pictures of other similar products in the hope that they have not erased the IC's used in a similar area of the design. a classic case is the DSO input channel IC's and the ADC chips. The clever members on this forum have often identified the anonimised chip by its location in the circuit and possible function, leading to a likely candidate from one of the well known manufacturers like Analogue Devices. This is where a forum such as this is invaluable. There are many very knowledgeable people here. If an anonimised chip cannot be identified, I am left with pin monitoring to establish the inputs and outputs, plus likely functionality of the IC. For simple gates and amplifiers this is relatively easy, but when you meet a complex VLSI chip things get more difficult to say the least. In such cases I tend to treat the IC as just a black box and detail its inputs and outputs. Once the reverse engineering of the schematic is complete it is sometimes possible to work out the blocks functionality. FPGA's are a classic case of a 'black box' as the configuration is not normally available or extractable in any meaningful way. The 'Resin Blob' IC's are also quite common in Chinese equipment. No clue is given to the identity so it must be extrapolated from the measured functionality. Multi layer PCBs can make this even more difficult as not all die connections can be seen or probed.

Another pet hate of mine is the PCB that contains lots of glue logic and little else. As the chips are configured in a format only known to the manufacturer, you basically have a schematic with 'black boxes' connecting to other 'black boxes'. Little help in working out whether the board is working correctly or not. At least with discrete logic chips and chips for which datasheets exist you can work out the functionality and correct states that should be seen.

Anyway, I have waffled on enough so I will finish here.

Best Wishes

Fraser
« Last Edit: April 02, 2015, 11:24:31 pm by Aurora »
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Offline Singapura

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Re: PCB Reverse-Engineering
« Reply #13 on: April 03, 2015, 07:27:03 am »
Hi Fraser (Aurora)

Thanks for your kind support!

Yes, I feel the same way you do when face with anonymised components (especially ICs) i.e. have their markings erased or covered with tough opaque compounds, as well as resin blob multi-pin unknowns (usually hybridized custom parts). I mentioned this in the footnote of my book under legal and copyright issues, commenting that some OEMs go so far as to use programmable logic devices or embedded designs with security bit protection, or even produce their own ASIC or proprietary components,  in-house or out-sourced, just to be sure that there is no way to reproduce a functional copy of their product but to go back to them for repair. It's understandable for the protection of their design and business, but can also be a sword that cuts both way in that customers may then opt for COTS to prolong their investments on the systems they're purchasing, unless the OEM happens to be the sole proprietor of certain ground-breaking technology or the expert designer house of that particular system.

Even if such obstacles are not an issue to contend with (i.e. not present on the PCB), one may still find certain design challenging because the hardware designer intentionally used peculiar approach in circuit topologies that defy conventional knowledge. PCB reverse engineering is more of an iterative as well as incremental process in which one constantly make adjustments and even major changes to the schematic's interconnectivity as it takes shape, and more of the inter-relatedness between components are discovered. So besides having a resolute spirit that is needed to see one through the tough exercise, some degree of being able to visualize and a sense of artistic proportion are invaluable too.

In my humble opinion, basic preparation such as gathering the necessary datasheet and information of components present, ascertaining the identity of the parts and creating a BOM for quick reference and keeping tabs, acquainting with the PCB layout and establishing a strategy, etc. will help greatly to reduce time and effort when the real work begins.

No matter what, doing reverse engineering on a PCB is always a pleasurable challenge that stimulates our engineering mind and curiosity, and once you have it figured out and pieced up, it's like Sherlock Holmes solving a mystery case - the satisfaction is immensely gratifying.

Do leave me your frank review at Amazon after you've received and gone through the book. Much appreciated!

Cheers!
Singapura
« Last Edit: January 05, 2018, 07:57:27 am by Singapura »
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Online Fraser

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Re: PCB Reverse-Engineering
« Reply #14 on: April 03, 2015, 10:28:33 am »
@Singapura,

It will be a pleasure to provide feedback on your book. As you have already highlighted, I have gone a little further than your books target audience in terms of my analytical equipment inventory so I will keep that in mind. The basic process will be the same however and your use of Visio greatly interests me.

I am also minded to start a new thread that details companies who are willing to provide the public with schematic diagrams fro their equipment. Some will do so for free whilst others choose to sell a complete service manual for a nominal charge (cost of production).

Examples of such friendly companies are Hameg, Digimess (Ex. Grundig) and Thurlby Thandar Instruments (TTi). I have found that it is always worth contacting a companies support agents and advising them that I wish to repair their product myself and request a schematic or service manual. It can save a lot of reverse engineering if they agree to help  :-+

As an example I bought a Hameg 200MHz HM-2005 oscilloscope recently. From past experience I knew that Hameg will release schematics to the public. Hameg used to include the schematic in their user manuals but that ceased when R&S bought them. I contacted Hameg customer support and requested the schematic diagram. It was sent to me by return email. A great company to deal with.

I will advise when I have the book in my hands  :)

Best Wishes

Fraser
Cogito, ergo sum
 

Offline albert22

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Re: PCB Reverse-Engineering
« Reply #15 on: April 03, 2015, 03:38:03 pm »
Thanks you guys for your useful insights. The SF10 seems like a wonderful aid. 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.
In some smps I had to unsolder the transformers because its windings were almost a short.
As you say it is very rewarding and a opportunity to learn new things, as you try to match the datasheets and app circuits with the actual implementation.
Regards
 

Offline Singapura

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Re: PCB Reverse-Engineering
« Reply #16 on: April 06, 2015, 03:52:54 am »
Hi Albert22,

You are right to note the importance of assigning reference designations (R, L, C, D, U, etc.) to unmarked components before doing PCB reverse engineering. I am quite surprised that you use Microsoft Powerpoint to create the PCB layout from a photo-shoot of the board, considering its drawing tools are quite basic. But I guess if your aim is to name the components without caring too much for its artwork then that's fine.

I'm a perfectionist which is why I opted for Visio to do the job because it allows me to create pretty complex and nice component symbols for both the layout and schematics with ease, and working on the PCB with a beautiful layout artwork in a way inspires me better. There were instances where I photocopied the PCB (provided it is flat enough without those irregular, protrusive components), grayscale and lighten it, and use it as reference to place my Visio symbols over the component locations, which is much faster. Of course, you need to take care to scale the photo correctly for accurate placement, as well as the perspective errors associated with scanning.

My book also discussed this issue on unmarked components in chapter 2. Attached is an artwork of another PCB from a payload control and logic unit that I worked on. Hope it'll inspire you to upgrade to a better drawing tool for your future RE endeavors. For me, Visio is the way, unless you have the time to pick up an EDA tool to master its intricacies and steep learning curves, with the intention to reproduce the PCB. RE is a tough and laborious undertaking, and good artwork serves to document your hard work as well as professional portfolio.

Singapura
« Last Edit: March 02, 2019, 09:46:47 am by Singapura »
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Offline Singapura

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Re: PCB Reverse-Engineering
« Reply #17 on: April 06, 2015, 04:01:15 am »
Oh, before I forget, reasons for having a PCB layout in print and electronic form:

1. Proper documentation of the PCB, including missing reference designators and additional data you might care to put in, such as the BOM side by side for quick reference.
2. Ease of locating specific components since it is in electronic form and therefore searchable even across multiple pages (Visio supports multi-page drawings).
3. Facilitate marking  (highlighting) of probed points to allow you to view your progress and cut down on repetitive probing, saving time and reducing wear or possible damage to the PCB.

See attached photo (also included as a 300dpi picture in my book) for an idea what I just said above.
The best experiences of our engineering careers and endeavors can become a lasting legacy for future generations of engineers.
 

Online Fraser

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Re: PCB Reverse-Engineering
« Reply #18 on: April 07, 2015, 03:41:15 pm »
Just arrived from Amazon.co.uk

Very nice quality book with very good paper and excellent image quality

 :-+

Sat in my conservatory enjoying the rare British Sun, perfect for a quick browse of the book  :)

Aurora
« Last Edit: April 07, 2015, 03:43:32 pm by Aurora »
Cogito, ergo sum
 

Offline albert22

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Re: PCB Reverse-Engineering
« Reply #19 on: April 07, 2015, 11:04:42 pm »
Singapura
Thank for your advice. You get very nice layouts indeed. 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.
For detailed documentation and pcb I use Altium. Although not for RE. A drafted schematic serves me well for repair or learning what is going on.
Regards
 

Offline Singapura

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Re: PCB Reverse-Engineering
« Reply #20 on: April 08, 2015, 02:10:48 am »
Hi Aurora

Wow! I feel excited just knowing that someone as experienced as you in RE are reading my book! And seeing the book in print brings a sense of joy to my heart too...

Yeah, the weather in UK tends to be overcast most of the time, so having good sun to enjoy is rare indeed! When I was in UK about 10 years ago, I remembered seeing a man walking his dog in the light rain on my way to a business meeting.

Hope you'll enjoy my style of writing (I tried to make it as engaging and narrative as I could without losing the engineering focus) as well as the content of the book.

Singapura
The best experiences of our engineering careers and endeavors can become a lasting legacy for future generations of engineers.
 

Offline Singapura

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Re: PCB Reverse-Engineering
« Reply #21 on: April 09, 2015, 08:42:53 am »
Just to revisit the idea of distributing my book in e-format. After doing a bit of researching at the CreateSpace forum and hearing from other self-publishing authors, the risk of piracy is too much to take for the nine-months of hard work I put in, so I've decided to stick with the printed form of distribution on CreateSpace eStore and Amazon (US and UK).

The price of the printed book may be a little high, but its reasonable considering it is full-colored and uses good quality paper with 300 dpi resolution photos and illustrations. On top of that, I'm also giving away freebies that are downloadable at my website, some of which are supplements to my book which I'd like to include in but didn't because that would make the price too high no one will want to buy or afford it.

The latest is an ebook containing 152 pages of prefixes and suffixes of IC part numbers from 90 semiconductor manufacturers, which I've just put in my blog for download. It is in rar format and freely downloadable but you'll need the password to access the content, of course. (see attached snapshots)

So, Aurora, if you're following this post, you may want to go get your copy. I'm almost done with the through-hole layout  Visio stencils for DIP (300, 400, 600), PGA, and ZIP packages (ICs, footprints and sockets) totaling 210 symbols. Once they're ready I will also put up in a separate page for download.

That's my way of saying thanks to those who support my effort in writing my first book, and to add value for their money.  :)
The best experiences of our engineering careers and endeavors can become a lasting legacy for future generations of engineers.
 

Online Fraser

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Re: PCB Reverse-Engineering
« Reply #22 on: April 09, 2015, 06:28:31 pm »
@Singapura,

Yes I am monitoring this thread  :-+

I have not had much spare time to delve deeply inside your book (relations staying with us at the moment) but what I have read is most excellent and I congratulate you on your excellent writing style. Very easy to read and a true accomplishment in the form of this book.

Your kind gift of Visio art to purchasers of the book is most welcome and a path that I wish other book authors would follow. I have had many books with a CD included but the very fact that such is present bumps the price up in the UK as it ceases to be a VAT free book and becomes software adding 20% to the price !

When I look at the work that you have put into this book, I feel the asking price is more than justified and, as you have stated, publishing a book with such quality paper and images is not cheap.

I am having a bot of a book 'moment' and have also purchased the Art of Electronics today. That book is a little larger than yours at 1000+ pages and has a retail price of £60, but it currently has a far greater production run.
 
It will be in good company sitting along side your book in my lab library  :-+

Best Wishes

Fraser
« Last Edit: April 09, 2015, 07:27:40 pm by Aurora »
Cogito, ergo sum
 

Offline Singapura

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Re: PCB Reverse-Engineering
« Reply #23 on: April 10, 2015, 06:28:45 am »
Hi Aurora

Glad to hear that you're enjoying my book thus far, and for understanding the constraint imposed on the price. I've actually approached a publisher prior to doing it on CreateSpace and the cost of printing a copy was almost double I immediately scrapped the idea. I've done quite a bit of homework in order to ensure my potential readers get the best quality at the most reasonable price, so thank you for your kind remarks.

I guess the years of doing repair and reverse-engineering, and having to write service and failure analysis reports had in some way sharpened my ability to express the accumulated knowledge in written form. In fact, the book went through a number of revisions in the course of writing - at times while I was working on a later chapter, some flashbacks would occur in my mind about certain earlier topics that are related and I'd go back to re-read and revise those sections with additional illustrations just to make the flow of thoughts better and more coherent. And yes, I took great pains to do and re-do the photos and artworks so they'll appear nice on print.

Though my book is considered complete in itself in terms of the fundamentals of RE, indirectly I still treat it as a work in progress by supplying my readers with complementary materials and works, something like an after sales support, as much as I can, in the form of free downloads on my website and blog. This is one way to offset the cost of the book and to make it available in the shortest possible time (which still took me almost a year). I'm sure my readers will love to have such surprises and bonuses instead of thinking that their entitlement ends with the sale of the book.

I have a copy of The Art of Electronics too, albeit it's the second edition. I think your copy is the third and latest edition available on Amazon. It's a classic and must-have reference of every electronic engineer.

Wishing you a wonderful time of bonding with your family and relatives during their stay with you. Cheers!

Singapura
The best experiences of our engineering careers and endeavors can become a lasting legacy for future generations of engineers.
 

Offline Singapura

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Re: PCB Reverse-Engineering
« Reply #24 on: April 13, 2015, 11:59:04 am »
Just put up the through-hole IC layout symbols (210 shapes in six stencils) on my website blog for buyers of my book to download at:

http://www.visio-for-engineers.com/blog/through-hole-layout-symbols

These include DIP-300, DIP-400, DIP600, DIP-SKT, PGA and ZIP packages.
The DIP packages include six different types (four plastic, one ceramic and one hermetical ceramic) plus two footprints (component and solder side).
They will be made available for purchase at $24.95 for the general public at a later date on my website store section.
« Last Edit: April 14, 2015, 06:44:05 am by Singapura »
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