TIP: How to read unreadable IC/transistor lettering

Yes, just like magic, rub the magic lantern and say abracadabra, well it is pantomime season . I could not read 3 of the 5 characters on a heat damaged TOP66 power transistor. I wondered if a sort of "brass rubbing" would work. I just happened to have some plummer's PTFE tape to hand ( nominal 0.05 to

0.08 mm thick). Laid a piece over it, rubbed with a finger nail, and the missing characters came up like magic. As the characters remained on the PTFE, as an image , I realised you could use this technique to read IC lettering where it is imppossible to read, because of constrictions and inability to introduce a mirror or even just where you cannot get the illumination at just the right angle to read. You need access space enough to introduce a piece of PTFE and then rub it with the wooden end of a small artist's brush, or similar, wrapped in some of the PTFE, so it rubs easily without dragging. Don't rub too firmly because you want the relief print to show as clear and the rest of the PTFE becoming translucent rather than the original white. Remove and read with a backlight or against something matt black. Maybe a couple of attempts to get a clear image in all parts of the label. May even be worth trying on reverse-engineering-proofed, rubbed off, IC lettering.

-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on

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Reply to
N Cook
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Cool. That's a lot cheaper than what I thought of when I read the Subject line.

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Reply to
JeffM

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n

There is a much more impressive system using phase array Xray or MRI or something of very high 3D resolution to read scrolls/ medieval pipe rolls etc without unrolling them

maybe

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but I've not time to download it at the moment

-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on

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Reply to
N Cook

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