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How To Identify Missing/Hard To See IC Part Number

By Jestine Yong on September 11, 2014

I’ve got an email about an LCD inverter board that the inverter IC part number was missing/hard to see. Sometimes the part number just faded away (became blur) after a number of years used. I suggested to him 6 ways that he can use to solve the problem.

If you can’t see the part number you can:

1) Ask forum members

2) Compare with a similar board

3) Call/email repair friends for help

4) Download the exact schematic diagram

5) Download schematic diagram that has similar model (EX- Equipment (say a TV) with the model of SB3100 usually have a quite similar design with equipment with model SB3101 and etc).

6) Think of modification of using an external inverter board. This requires more time as you may need to understand all the important signals. This scenario is the same when I came out with an ebook on how to modify a small switch mode power supplies when there was no data or even missing/burnt components in the power supplies.

The above method is not limited only to the inverter ics. In fact you can use the above first 5 ways to identify other type of components part number too. If you have other suggestion I would like to hear from you in the comment section-thanks.

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electronics repair

45 Comments

Robert

September 11, 2014 at 12:28 pm

Thanks Mr. Yong. Also sometimes it helps when you put a little bit of spit on the IC.

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- Jestine Yong
  
  September 11, 2014 at 1:32 pm
  
  Hi Robert,
  
  That is also a good tip! Thanks.
  
  Jestine
  
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  Reply
  - chard
    
    June 2, 2023 at 7:40 pm
    
    where can i find schematic diagram in internet either paid or free
    
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    Reply
    - Jestine Yong
      
      June 3, 2023 at 9:47 am
      
      Hi Chard,
      
      Try www.eserviceinfo.com
      
      Jestine
      
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      Reply
- Jestine Yong
  
  September 11, 2014 at 9:36 pm
  
  HI Robert,
  
  There was another comment by another reader:
  " on the topic of identifying faded IC numbers, I had some luck with rubbing a light oily substance over the IC , sometimes the letterwork re-appear just enough to identify it.
  
  Afterwards I clean oil with alcohol-based substance.
  
  Kind regards
  Danie
  
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  Reply
- Vipin
  
  March 15, 2018 at 10:29 pm
  
  Hi
  I got it this type ic. That have 8 pin but no. Are rubbing. All boards rubbed by manufacturer now I cannot find ic no. Can u help me Mr.
  
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  Reply
Phumlani

September 11, 2014 at 4:48 pm

I think it will save time not to try to put the external in inverter board ,But thanks any way,those were good tips

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- Jestine Yong
  
  September 11, 2014 at 9:32 pm
  
  HI Phumlani,
  
  You are welcome!
  
  Jestine
  
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marco tapia

September 11, 2014 at 5:31 pm

I love your work especially in troubleshooting switch mode power supplies and the modification secrets which has powerful methods which you can use not only on power supplies but for any electronics work but surfing the net and asking for help is best way to find information when everything else fails.

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- Jestine Yong
  
  September 11, 2014 at 9:33 pm
  
  HI Marco,
  
  Thanks.
  
  Jestine
  
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  Reply
carlos

September 11, 2014 at 7:24 pm

I put a little bit of thermal paste on the component and and then do the cleaning works perfect ....

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- Jestine Yong
  
  September 11, 2014 at 10:55 pm
  
  HI Carlos,
  
  Thanks for the suggestion.
  
  Jestine
  
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Pepper Myers

September 11, 2014 at 7:56 pm

Very good advice Mr.Yong!
Basic component identification can be difficult too.
The older tech may not be keeping up with the times
and the newer tech has never seen the older components.
The PCB silk-screen can be valuable in discerning a
components category, like IC-,Q-, R-, C-, L-, and so on.
Then you might be able to tell the proper orientation of
a polarized electrolytic so they are not inserted backwards!
I have actually photographed a PCB before repair…
Thanks,
Pep

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- Jestine Yong
  
  September 11, 2014 at 9:34 pm
  
  Hi Pepper,
  
  Thanks for sharing.
  
  Jestine
  
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  Reply
Pete Singh

September 11, 2014 at 10:11 pm

Hi Jestine , keep doing what you doing I love your articles and the books you wrote.

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Reply
- Jestine Yong
  
  September 11, 2014 at 10:53 pm
  
  HI Pete,
  
  Thanks for the support!
  
  Jestine
  
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  Reply
Yogesh Panchal

September 11, 2014 at 10:51 pm

Dear sir,

1. Clean up the text with a cotton swab dipped in rubbing alcohol.
2. Wait for the alcohol to evaporate and rub yellow or white chalk on markings.

For detail please visit this web page :
http://electronics.stackexchange.com/questions/5186/how-to-read-the-text-printed-on-top-of-every-ic

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Reply
- Jestine Yong
  
  September 11, 2014 at 10:54 pm
  
  Hi Yogesh,
  
  Thanks for the link.
  
  Jestine
  
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  Reply
neeraj yadav

September 12, 2014 at 12:02 am

Sir, how can i found smd codes and identity that, mount on lcd tuner board?

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Reply
- Jestine Yong
  
  September 12, 2014 at 10:37 am
  
  Hi Neeraj,
  
  For tuner board the best is to refer back to schematic but usually very hard to find such diagram for tuner board. Some or many of the smd parts are without number thus making it very difficult to identify it. The methods suggested by fellow readers are mainly for when the part number of the ic already faded.
  
  Jestine
  
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  Reply
Andre Gopee

September 12, 2014 at 2:38 am

Hi Jestine, Thanks for all your help in the past... I came across a product that the manufacture scrape off the IC number and for years I tried to find out what was the part number. I kept trying different IC until I finally got one to work. It took a long time but it was wort it in the end and know I can finally repair hundreds of them in a short time making me look like a champion. But without your ebooks I could not have done it. Another that I do it is to put the IC under a microscope and angle the IC in different direction and I am able to see the number. This work great as well.

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Reply
- Jestine Yong
  
  September 12, 2014 at 10:32 am
  
  HI Andre,
  
  Thanks for the support and the great tip too.
  
  Jestine
  
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  Reply
- zed
  
  September 12, 2014 at 12:52 pm
  
  hi andre,
  
  What equipment do you repair that you found the part number of ic? can you share to us IF YOU DONT MIND so that if someone encountered it in other country like here in the Philippines we can know the ic part number. THANKS.
  
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  Reply
Lynn

September 12, 2014 at 2:41 am

Easy trick. Take a little white heat sink compound rub it on then remove excess. The numbers now can easily be read.

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Reply
- Jestine Yong
  
  September 12, 2014 at 10:31 am
  
  HI Lynn,
  
  Thanks for the tip. It seems that are many ways to see the part number as posted by fellow readers:
  
  1) Use oil
  2) Use heat compound/thermal paste
  3) Use thinner
  4) use saliva
  5) Use alcohol then rub with yellow/white chalk
  6) Use microscope
  
  The more the readers share the more we know. So if any of the readers here have any good repair articles you can send it to me and if the content is good I will post it into my blog.
  
  Thanks.
  
  Jestine
  
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  Reply
leonard williams

September 12, 2014 at 6:06 am

i alwayse used thinner to clean the part nothing works better

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Reply
- Jestine Yong
  
  September 12, 2014 at 9:57 am
  
  HI Leonard,
  
  Thanks for sharing.
  
  Jestine
  
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  Reply
philip odhiambo

September 12, 2014 at 7:09 am

Thanks Jestine.Another one is to cumunicate with the manufacturer for the circute board or part number.But i tried one and did not succeed.Do they realy heilp ?

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Reply
- Jestine Yong
  
  September 12, 2014 at 10:34 am
  
  HI Philip,
  
  If you have tried all the method above and still not be able to solve it then the last option is to modify it by using an external board.
  
  Jestine
  
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  Reply
Atish Chand

September 12, 2014 at 4:27 pm

Hi Jestine
brilliant ideas friend, sometimes,i get stack on this issue ...........

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- Jestine Yong
  
  September 12, 2014 at 7:31 pm
  
  Hi Atish,
  
  Thanks.
  
  Jestine
  
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  Reply
Atish Chand

September 12, 2014 at 4:39 pm

Sometimes,tilting theIC s and rflecting against light also number becomes visible........

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Mojy

September 13, 2014 at 2:58 am

Dear Jestine,
Hi & fully health for you.
You can try this one too.
Take a photograph by your mobile from an IC when its flash
is active and in diferent angles. One angle give you
the best view. I've tested it.
Thank you for your useful articles.

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Reply
- Jestine Yong
  
  September 13, 2014 at 9:51 am
  
  Hi Mojy,
  Thanks for the tip and will try it.
  
  Jestine
  
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  Reply
Abdoulie Bah

September 13, 2014 at 5:07 pm

Thank you very much you really great.

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Reply
- Jestine Yong
  
  September 14, 2014 at 7:44 am
  
  You are welcome!
  
  Jestine
  
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  Reply
reza

September 13, 2014 at 9:38 pm

hi mr yong
thank u for this good artilce

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Reply
- Jestine Yong
  
  September 14, 2014 at 7:47 am
  
  You are welcome!
  
  Jestine
  
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  Reply
Raymundo Saura

September 14, 2014 at 8:27 am

Good morning sir, Thanks for sharing sir Jestine very informative i learning a lot from all the things you share

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Bartek

September 15, 2014 at 6:16 am

First of all I start look in google for board number and on some of pictures over the web you can find this number.If it fail then split on the part as one friend mention before.
Best regards for Your good work Mr. Yong

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Taring K Arioka

October 31, 2014 at 12:25 am

Hi Jestine
It so good to learn new ideas from you. Thank you for your helpful article

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- Jestine Yong
  
  October 31, 2014 at 8:27 am
  
  Hi Taring,
  
  You are welcome!
  
  Jestine
  
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  Reply
Amir Mukhtar

February 6, 2015 at 3:36 pm

Thanks you Sir Jestine for Guidance and tips .

We are very Greatfull to you for BLOG Forum and Expertise Sharings.

YOurs Student
Amir Mukhtar Ashrafi

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mariwan

May 20, 2015 at 12:37 am

You can take a photo and try to change color or use different filter to make the picture as x_ray picture ..etc... It will help you to see things that is not possible otherwise

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- Jestine Yong
  
  May 20, 2015 at 6:59 am
  
  Hi Mariwan,
  
  Thanks.
  
  Jestine
  
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  Reply