EEVblog® Electronics Community Forum
Electronics => Repair => Topic started by: MikeK on September 08, 2022, 01:24:22 am
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Got another 22" monitor. This one for free. I'm not sure I can remove this tape without destroying it. Is it conductive? It's in three separate places. Do I need it?
[attachimg=1]
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It's probably intended to provide some RF shielding, it might also just be used because it sticks well to the aluminum and is sturdy. It looks like HVAC aluminum tape, you should be able to get it from any hardware store that sells ducting components. I know Home Depot carries it.
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Note that there are special types that have (or... are supposed to have, anyway) conductive adhesive, so that shielding is indeed achieved.
Seems unlikely that it would be purely structural; polyimide is more common for that I'd say, and tougher. Or a somewhat thicker polyester.
Tim
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Assuming none of the corners or edges are tucked under, a quick check with a DMM of the resistance between the top surface of the tape and the adjacent chassis would tell you whether it has conductive adhesive. The top left corner looks a little dodgy, so if you get a low ohms reading, lift the tip of the corner slightly with a scalpel and re-test
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if you need to take it out then re-apply again use a hair dryer to easily peel it off or if you want to keep it but take it apart just slice it in the middle where it makes contact to those surface, usually used for shielding of some sort.
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Even if you damage it you can get a roll of copper RF shielding tape for £9 from DigiKey...
https://www.digikey.co.uk/en/products/detail/3m-tc/3M-1194-6-X-12-25/7724580 (https://www.digikey.co.uk/en/products/detail/3m-tc/3M-1194-6-X-12-25/7724580)
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Hardware strore near in the ductape section. This stuff is also used in HVAC, sealing vents and ducts etc.
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I'm skeptical of the HVAC tape? Is it conductive? It certainly doesn't need to be. This tape has low resistance, even on the back (adhesive) side.
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I also wouldn't expect aluminum HVAC tape to have a conductive adhesive, and the roll I've got certainly is non-conductive, however you could overlap its edges with much narrower (and cheaper) copper tape with conductive adhesive.
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I very recently had a 22" Samsung monitor opened up and there was no foil tape. I'm guessing that's because the backlight in that one is LED and the backlight in this HP unit is CCFL.
I'll probably go with the DigiKey foil tape in my next order. At least I'll have some if I need it in the future.
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It's probably just shielding. I would just cut it with a knife and leave it in place, rather than peeling it off. When you reassemble just smush the cuts back together.
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Try the hairdryer method.
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If I manage to unstick the tape with heat, or whatever, what is good for protecting the adhesive back until I restick it? Plastic cling wrap? "Anti-static" parts bags from DigiKey? Household aluminum foil? Cooking parchment paper? My psychic powers?
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If you have a backing sheet from some kind of adhesive labels that should work. Personally I don't bother though, I just peel it off as best I can and stick it back on as intact as possible, sometimes I don't even bother, I never had a problem.
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This is just foil tape. You can just use some aluminium foil tape as a replacement, but it is not worth it.
It should pull off with some force and you can stick it back down. If it comes apart, remove it and use some duct tape or something.
A lot of monitors use this stuff to keep stuff together on the aluminium/steel backing of the LCD.
I have an LG screen that used it to hold the controller board as the monitor had no fasteners at all. Just clamshell construction. :palm:
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This is just foil tape. You can just use some aluminium foil tape as a replacement, but it is not worth it.
It should pull off with some force and you can stick it back down. If it comes apart, remove it and use some duct tape or something.
A lot of monitors use this stuff to keep stuff together on the aluminium/steel backing of the LCD.
I have an LG screen that used it to hold the controller board as the monitor had no fasteners at all. Just clamshell construction.
I'm skeptical. For one thing HP would have used cheaper tape than the foil tape with conductive adhesive if they could have. See the first image below. The four black strips are cheaper tape that held wires in place. The three strips of foil tape hold nothing. The power supply cage is riveted to a larger metal frame that is itself screwed to an outer frame.
My recently repaired Samsung monitor was constructed as you've observed, though, with the power supply box only taped down and not fastened to anything. Second image below.
[attachimg=1]
[attachimg=2]
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I'm pretty sure the foil tape is just there to help it pass EMC testing, it's unlikely to cause any real problems if you leave it out.
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If this piece of tape would have any significance, it wouldn’t be aluminum tape. Since it is aluminum, I highly doubt that the glue on the back is conductive, like copper tape. It’s just plain HVAC tape.
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Its probably there specifically to meet the FCC standards. And it would need to be conductive. However if you can tolerate some EMI it may not be important. If its in a VNA or SpecAn its important.
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Followup: There was more metal tape inside, once I removed the power supply box. Was able to pull it all without much tearing. And it all stuck back down pretty well. This was a trash day find, with the backlight not working. All I had to do was resolder two CCFL bulb connections. Still looks pretty good for over 15,000 backlight hours on it.
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It's used to be secure and act as a ground path - what I've been doing is gently peeling it away, it usually retains enough adhesive that it can be re-used.