issues with IR Thermometer pen DT8220 - Page 1
Forum section: electronics / general

author: kalel
author_rank: Frequent Contributor
timestamp: October 03, 2017, 03:10:11 am
content: I doubt there's any hope here, especially not having the knowledge, repair skill (especially no SMD skill at all) or even having basic tools like a memory programmer. I want to share the experience just in case.I've bought this (black version, not from the link - just for example):https://www.amazon.com/Infrared-Thermometer-DT-8220-Pen-Type/dp/B00IC2A3DCAnd it had a bit strange readings. They didn't seem very consistent, while every x tries it gave what should be a "reasonable" result. I don't have a way to test it accurately.I looked at the sensor, and inside found what seemed to be like a piece of foil. This is the reflector taken off, and where the "foil" was above the sensor is marked. I don't have an image of the actual foil.Now, was this foil actually something important, to focus the light? I don't know. It seemed to have slightly curved edges and really seemed like something that shouldn't be there, and I wasn't happy with the readings as they were anyway. Once I opened the unit, and taken away the reflector from the sensor, the "foil" fell out by itself, so it wasn't an attached part to something.Anyway, after closing it, the readings seemed very strange (stranger than before? probably, but I didn't memorize the exact initial results). The manual does say that "10 cm" is optimal distance, but every single cm gives a drastically different reading (with skin for example). So I get readings like ~50 deg C for skin when holding it directly (no distance) and ~40 deg when I hold it about 10 cm away as recommended (it's hard to be exact here, how would you know to always hold it 10 cm away).I just tried my forehead, and it said 60 degrees C (it does say C, not F - setting it to F shows much higher readings). I tried different batteries (ones built in measured fine), same thing.I'm not sure what the cause is, and even without being able to fix it, it would still help me understand better if someone might know the reason for these readings. Was the foil-like thing an actual element that is normally used and by removing it and exposing the entire sensor (instead of just left and right edges of the sensor) to light ruined things? I assume it did mess up the calibration, but initial results weren't great either. So, if this was some foil that was not supposed to be there, and the factory calibrated it with that inside, it might need recalibration which I wouldn't be able to perform.Anyway, here are some images if anyone is interested in seeing the parts. They are not perfectly focused. The small damage on the plastic case (near the text) was not made by me. There's a small scrape like that on another position too (close to the reflector). I just looked at the packaging (plastic) and it was also burned at those spots. So probably it was burned from the outside after packaging. I think this shouldn't have anything to do with the accuracy.

author: kalel
author_rank: Frequent Contributor
timestamp: October 07, 2017, 11:10:52 am
content: I know that there isn't likely anything I could do to fix this (and those that could - it's questionable if it would be worth their time to do the actual fix), but I'm curious if there's any thoughts over:What that "foil" might have been, was it an element normally used or just something that got stuck between the sensor and reflective part in production.Any guess over the cause of the issue?I know I haven't provided much information (I don't have much knowledge about this and information to provide), but the answers might at least help consider if this or a similar model is worth getting again in the future.