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What type LIGHT do you use to read part numbers?

gary350

Well-Known Member
I have a terrible time reading part numbers on, transistors, mosfets, any black package with heat sink tabs. LED lights are blinding all I see is light glare.
Incandescent lights are better than LED but still hard to read. Real sunlight is best be we don't have sunlight in TN for 6 months all winter.

I cannot read color rings on resistors, LED light is the worse, old incandescent lights are better. Some colors don't show up as the real color. I have to ohm every resistor to see what they are.

Black, green, blue, body electrostatic capacitors with white letters are no problem.

I have a 3" diameter magnifying glass that is helpful.

What type light do you use to read part numbers?
 

tomizett

Active Member
I like to smear a little heatsink compound on ICs and transistors to make the lettering stand out.
I vaguely recall someone saying that green (I think?) LEDs where good for reading ICs, but I've not tried it.
 

sagor1

Active Member
I use a Loupe, a small magnifying lens that has x10, x20 or x30 power to read those really small lettering like those on SOT23 transistors, etc. At that magnification, a LED flashlight at reduced output (2 level output flashlight) is ideal for me.
If still having issues, look into those USB "microscopes" that are magnifiers with a lens you can adjust.
 

dknguyen

Well-Known Member
Most Helpful Member
Is it really the light that is the problem? Or just the smallness? I'd assume the presence of a loupe would be a far greater help than the type of light used.
 

alec_t

Well-Known Member
Most Helpful Member
As for tricky-to-decipher colour bands on resistors, I find it helps to get a close up photo of the component, then use the colour probe tool in an image processing app to determine the R,G,B components.
 

gary350

Well-Known Member
Is it really the light that is the problem? Or just the smallness? I'd assume the presence of a loupe would be a far greater help than the type of light used.
Good idea but, used salvaged parts have faded number. Bigger does not make almost invisible number easier to read. Magnifier is helpful for numbers not very faded.
 
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gary350

Well-Known Member
I have a desk lamp with a "grow" lamp see https://www.ikea.com/au/en/catalog/products/40373682/

Makes invisible writing easy to read.

Mike.
I have a work shop lamp. Maybe if I had a light bulb like a grow light that make light almost = to sunlight it might work to read part numbers. If I take hard to read parts outside in the sun I have no trouble reading them. 2 days this week is the first time we have seen the sun in 2 months. Now it is over cast and rain again. TN gets 250 days of rain per year.
 

Mickster

Well-Known Member
I use a combination of an illuminated desktop magnifying lamp on an articulated arm, and a regular incandescent/LED flashlight, plus the MKI eyeball.
MKI eyeball looks through the illuminated desktop magnifying lens, and the DUT is manipulated, along with the flashlight, to provide the most legible result. Shining the flashlight at a shallow angle, across the face of the device, gives good results IMO.
 

gophert

Well-Known Member
Most Helpful Member
If I find chips with the white letters flaked off, I heat them gently under an incandescent bulb then place them in a small box with an open superglue bottle. The vapors of cyanoethylacrylate selectively deposits where the white letters were. Then I shake the chips in a ziplock bag with some talcum powered - the white powder bonds to the superglue and the letters are now clearly visible. Unfortunately, the superglue/talc does not bond well to the chip and it quickly flakes off so you need to take a close up picture before the ink flakes off. Once I have a clear photo, I white the talc superglue off of the chip and then apply some positive photo-resist film to the chip, I then use the NOTES app on my iPad to type the chip's name, I take a screen capture and then use an image manipulation app to flip the image and scale it to appear about the size of the chip on my screen. I then set the iPad directly on the chip to expose the photo-sensitive emulation (set the screen to brightest and turn off the evening (no UV) reading backlight). Then dip the chip in a bicarbonate solution to develop and then wipe acrylic ink across the entire remaining emulsion - let it dry overnight. Then gently rub the ink to lift the photo-resist to leave a perfectly printed set of white letters. At least I think that all works, I've never tried it, I only buy new parts from good distributors. I did have fun occupying my time by writing this as I wait for my red-eye back to Pittsburgh (CES was so cool in Vegas).
 

Pommie

Well-Known Member
Most Helpful Member
If I find chips with the white letters flaked off, I heat them gently under an incandescent bulb then place them in a small box with an open superglue bottle. The vapors of cyanoethylacrylate selectively deposits where the white letters were. Then I shake the chips in a ziplock bag with some talcum powered - the white powder bonds to the superglue and the letters are now clearly visible. Unfortunately, the superglue/talc does not bond well to the chip and it quickly flakes off so you need to take a close up picture before the ink flakes off. Once I have a clear photo, I white the talc superglue off of the chip and then apply some positive photo-resist film to the chip, I then use the NOTES app on my iPad to type the chip's name, I take a screen capture and then use an image manipulation app to flip the image and scale it to appear about the size of the chip on my screen. I then set the iPad directly on the chip to expose the photo-sensitive emulation (set the screen to brightest and turn off the evening (no UV) reading backlight). Then dip the chip in a bicarbonate solution to develop and then wipe acrylic ink across the entire remaining emulsion - let it dry overnight. Then gently rub the ink to lift the photo-resist to leave a perfectly printed set of white letters. At least I think that all works, I've never tried it, I only buy new parts from good distributors. I did have fun occupying my time by writing this as I wait for my red-eye back to Pittsburgh (CES was so cool in Vegas).
Might have to try this next time. :D

Mike.
 

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