Uni-T ut33d ampere displays over load repair help request - Page 1
Forum section: electronics / repair

author: ABHIRAMSHIBU
author_rank: Contributor
timestamp: July 02, 2017, 02:12:59 am
content: I have been using this multimeter for 3 years. It was working fine until last week I accedentally blown off fuse while I was measuring mill amps. Then I replaced the fuse. Here in India we get cheep crusty fuses and I put one with 0.5mA rating. Yesterday it happens again, now with fuse ampere measurement of the multimeter is broken. All ampere ranges will give 1 (overload) even 10A when not connected.I have looked inside the multimeter and didn't find any thing burnt or broken.All other measurements work and is upto spec.I can't afford a new multimeter now.. If I could repair it, it would be better..Can anyone please tell me what to check and what is most probably blown off.There is a detailed review with all teardown pictures posted in this forum by another user.I didn't find any schematics for this multimeter and it has very low input protection but better than cheep Chinese metres to say..

author: MosherIV
author_rank: Super Contributor
timestamp: July 02, 2017, 12:27:13 pm
content: Most people would just get another meter since it is so cheap, however since you are on a budget.The UT33D is basically the DT830D re-packaged by Uni-T.Search for the DT830, the schematics are on the web. Some people have dedicated web sites to itWatch Dave's video on how DMMs work to gain an understanding of how they work in general.My guess it that you have damaged the transistor the amplifies the current sense voltage since both the fused and unfused ranges show the same fault.PS use a properly rated fuse in future, this is what happens if you do not.PPS have you considered getting another better meter and keeping this one as a back up all be it without Amps measurement working?

author: ABHIRAMSHIBU
author_rank: Contributor
timestamp: July 02, 2017, 03:25:48 pm
content: Quote from: MosherIV on July 02, 2017, 12:27:13 pmThanks for the info.. I will try to get the schematics of dt830d and also will watch the video about how multimeter works.I will check for that transistor, if it's there in the schematic.When you are free, please suggest me a multimeter with most of the features a hobbyist would need and is very cheap...If I'm able to repair this multimeter, it's a bonus..

author: testian
author_rank: Regular Contributor
timestamp: July 02, 2017, 05:32:41 pm
content: Quote from: ABHIRAMSHIBU on July 02, 2017, 03:25:48 pmWhat is your definition of cheap? I have the UT61E (~50€) and i am quite satisfied satisfied with it.Do you have other measurement equipment to check for faults?

author: MosherIV
author_rank: Super Contributor
timestamp: July 02, 2017, 05:42:14 pm
content: QuoteI think your definition of cheap is different to my definition of cheapIn general, you should be checking out the test equipment forumhttps://www.eevblog.com/forum/testgear/If you want a specific dmm to look at, try the UT139C. It is safe to measure mains and has all those extra feature like temp, freq and capacitance that some seem to want.If you want to measure current without the risk of blowing more fuses, look at the UT210E clamp dmm. I have one and it does what it is famed to do, measures dc Amps down to 1mA. Though I would not use it to measure mains voltages.Hope you consider them to be ok price wise. Stay away from things like the Vici and Aneng. There is a reason why they are cheap :About 6min30sec into the video, the Harbour freight explodes in a plasma fire ball .This is why cheap meters are cheap - because they either do not know what they are doing or they are cutting costs over safety.Edit: The UT61E is not a good meter for you. It is cheap for a DMM with that accuracy specifcation BUT there are doubts on whether it stays in spec. I have one and while it is impressive for the price, it is only worth getting if you are after a meter with 0.05% accuracy (most hobbiest do not). No I have not checked the accuracy has stayec in spec

author: ABHIRAMSHIBU
author_rank: Contributor
timestamp: July 03, 2017, 02:33:17 am
content: Quote from: testian on July 02, 2017, 05:32:41 pmI'm mainly into power electronics.. dealing with voltages upto 400v max.My definition for cheap is maximum robustness ( robust for common tasks ), have so many functionality yet cost is less than other metres which do these tasks.Normally I have 3 metres1) UT33D2)DT830D ( crap meter bought this for current measurements when my Uni-T blown) it is for dc current3)MTQ666 AC clamp meter. (Mainly uses it for measuring high voltages and ac current)Normally in the past I used all crap dt830d meters. Sometimes when probing something the meter will blow off.. At last I was fed up and found eev blog. And saw that Uni-T is more robust and safe than dt830D. So bought which a Uni-T which is available locally and is in my budget.Now what are the down sides I see with Uni-T meter I have is it don't have a hrc fuse, and fast blow glass fuses which people sell locally here are not fast at all.I have seen this videohttps://youtu.be/cB0K5p7CgtEUni t did not do well in that test and he was able to blow the chipset. That makes it not repairable.Now I'm going for fluke 115 which is not good for micro amp measurements.. It is beyond my budget but if I try harder and save money, might be able to buy one. In that video he told it's very robust. So in my use case sinario it might not fail at all..I have experienced mutimeters blown into flames.. this happend when I was making a Tesla coil transformer and was probing the primary, it was roughly 200-300v but when I was away the meter burst into flames...I need to measure micro amps so for that I might make a circuit which converts ua to something like Milli volts.Thanks all for your support

author: joeqsmith
author_rank: Super Contributor
timestamp: July 03, 2017, 03:50:10 am
content: But keep in mind, you damaged you meter after blowing a few fuses and I never do any sort of robustness tests with the current inputs.