How is this for 5€? DT830D teardown! - Page 1
Forum section: electronics / testgear

author: tmammela
author_rank: Contributor
timestamp: October 07, 2013, 02:55:56 pm
content: Hi! Just joined this forum after watching the Youtube channel for a few weeks. First I must say thanks to Dave, your videos are really inspiring! Got me back to doing some electronics stuff.I just want to show you this cheapo multimeter I got for five euros. No, it's not going to be my real multimeter, just a toy / spare meter while I wait for my online order to arrive. After watching the 50$ multimeter shootout, I was really expecting to find something terrible inside this cheapo. I was surprised to find that it's not that bad, at least to my newbie eyes. The input sockets are cheap of course, but the board layout and soldering quality seems ok, and it seems to have some input protection and ceramic fuse. Only problem I found was that the fuse was not properly inserted at factory, but that was easy to fix. What do you think, is this going to blow on my face?

author: TMM
author_rank: Frequent Contributor
timestamp: October 07, 2013, 03:20:54 pm
content: It's hard to do a bad pcb layout with so few components lol. Looks like we have a ptc, maybe a spark gap and what seems to be a ceramic mains appliance fuse. Hardly impressive but probably better than others at that price point. I still wouldn't be putting that near mains - for one the case doesn't seem to have very deep grooves around the edges so if it pops it is likely to burst open and eject shrapnel (assuming the front and back mouldings don't separate). It is fine if you plan to keep it on the lab bench away from high energy sources.

author: Robomeds
author_rank: Frequent Contributor
timestamp: October 07, 2013, 03:52:03 pm
content: Wow! That is worlds better than the Cen-Tec 830 Multimeters often 'sold' for free with any purchase at Harbor Freight in the US. I picked up about 5 for that price a while back.Anyway, that looks like someone said told the manufacture meet some minimum level of safety or get out. The HF ones by comparison are complete crap.https://www.eevblog.com/forum/reviews/harbor-freight-cen-tech-90899-small-teardown/I think the only safety bits on the HF models are a non-conductive housing (plastic vs metal), a current limiting resistor on the non-current inputs, a glass fuse, a recommendation to wear safety glasses when changing the battery (!), and a recommendation to have a 'friend' take the measurements for you.Seriously, from a safety POV the Cen Techs are crap! However, I have on occasion recommended them with the warning that they should only be used for low voltage stuff and never on things that are plugged into the wall.I noticed that on both voltage ranges that meter says 250V max. Interesting. I wonder if that is actually because the voltage range didn't meet a safety target or because they only used 250V fuses in the current ranges. It's cheaper to say don't test over 250V (which is probably a non-issue for most buyers of this sort of meter) vs buying better fuses.

author: Wytnucls
author_rank: Super Contributor
timestamp: October 07, 2013, 03:54:16 pm
content: At first glance, it looks pretty safe to me for a CAT II 250V rating . Nice PCB battery contactors, proper shielding, PTC, mA 250V polyswitch, grooved case. Just don't short the mA range on 250V, as it could damage the meter circuitry.

author: tmammela
author_rank: Contributor
timestamp: October 07, 2013, 04:47:46 pm
content: Quote from: Robomeds on October 07, 2013, 03:52:03 pmThis comment got my attention there:Quote from: AlphZetaObviously they are not from the same manufacturer, the real DT looks almost premium compared to that!Quote from: Robomeds on October 07, 2013, 03:52:03 pmMaybe it's both. Either way, it's good that there's no 1000 volt rating, someone might actually try it... I can't believe that HF one has 1000 volts on it...Quote from: RobomedsGift for a "friend" that one would want to get rid of.

author: tmammela
author_rank: Contributor
timestamp: October 07, 2013, 05:38:55 pm
content: What is that small trimpot used for? Can I use it to calibrate voltage readings if I have a reliable voltage reference available?

author: nikifena
author_rank: Regular Contributor
timestamp: October 07, 2013, 09:03:50 pm
content: Pretty clean inside for cheap multimeter

author: Lightages
author_rank: Unknown
timestamp: October 07, 2013, 09:37:05 pm
content: I am surprised! It looks like it actually is not a bad cheap meter. I would keep it on the bench only but for the price it looks quite well built and useable.

author: retiredcaps
author_rank: Super Contributor
timestamp: October 07, 2013, 11:35:31 pm
content: Quote from: tmammela on October 07, 2013, 05:38:55 pmMost 830 have a single trim pot for DC Voltage.Thanks for sharing photos of the insides of this 830. It is by far the best looking 830 internally.

author: amyk
author_rank: Super Contributor
timestamp: October 08, 2013, 01:31:27 pm
content: Quote from: Robomeds on October 07, 2013, 03:52:03 pmThat's aUL830, not a DT830. The basic design is the same but different manufacturers will have different board layouts. It looks like this one was a quick attempt at satisfying some safety standard, as there is no socket for hFE but the function is still there.I'm almost willing to bet the "250V" range will read accurately up to 1kV, it's just been derated for safety reasons.

author: tmammela
author_rank: Contributor
timestamp: October 08, 2013, 05:59:05 pm
content: Quote from: retiredcaps on October 07, 2013, 11:35:31 pmOkay thanks.Quote from: retiredcaps on October 07, 2013, 11:35:31 pmNo problem. I guess after all this little device has some serious bang for the buck!Quote from: amykI came with a little adapter that would fit to the probes for the hFE function.