Uni-T UT71E - Page 1
Forum section: electronics / testgear

author: h1386343
author_rank: Regular Contributor
timestamp: September 29, 2012, 02:06:50 pm
content: Would find at Uni-T UT71E scheme. And then dragged along a friend - waiting for repair and calibration. Without the scheme can not repair.

author: Lightages
author_rank: Unknown
timestamp: September 29, 2012, 06:31:07 pm
content: I am not sure what you are trying to say or ask. It is obvious that your first language is not English. What would be your first language?Anyway, the UT-71E is not a reliable meter and if you need to spend any money to get it or fix it, don't bother.

author: h1386343
author_rank: Regular Contributor
timestamp: September 29, 2012, 07:03:01 pm
content: Yes, you're right. Unfortunately I do not know English. Therefore translate text via googe. So forgive me.About Unitrend UT71E - I'm looking at this scheme multimeter. Very necessary. Help.

author: Wytnucls
author_rank: Super Contributor
timestamp: September 30, 2012, 04:00:39 am
content: Here is a calibration video for the E model. Ask the poster for some help.

author: nukie
author_rank: Frequent Contributor
timestamp: September 30, 2012, 05:19:07 am
content: Don't bother getting the last digit right, it loves to drift.tapatalk

author: h1386343
author_rank: Regular Contributor
timestamp: September 30, 2012, 05:32:43 am
content: Thank you for your answers. How to calibrate the I already know. This is a video I have. Now the problem is repaired. Therefore, a circuit diagram for UT71E. Help me find the schematic diagramm UT71E.

author: Smokey
author_rank: Super Contributor
timestamp: September 30, 2012, 06:22:32 am
content: I love how google translate makes everyone sound like a drunk yoda.

author: Wytnucls
author_rank: Super Contributor
timestamp: September 30, 2012, 06:42:50 am
content: Quote from: h1386343 on September 30, 2012, 05:32:43 amI have never seen a circuit schematic published for the 71 model. Best to ask Uni-T if they are willing to release it.What's wrong with your meter anyway?Mine came with a 3 year warranty in Hong Kong.

author: h1386343
author_rank: Regular Contributor
timestamp: September 30, 2012, 08:15:30 am
content: I have never seen a circuit schematic published for the 71 model. Best to ask Uni-T if they are willing to release it.What's wrong with your meter anyway?Mine came with a 3 year warranty in Hong Kong.Not all segments are displayed. And, strangely enough, he was approached by the display Voltcraft VC940. But he also does not work as well as native. Through google learned that Voltcraft VC940 exactly like UT71E. I found a diagram on Voltcraft VC940. But not sure that they are 100% the scheme are the same. There are even pictures of interiors. If you want I can put the scheme in this forum.Oh, and I doubt very much that the company UNITREND, so simply because the scheme will give to your brand.

author: h1386343
author_rank: Regular Contributor
timestamp: September 30, 2012, 09:32:43 am
content: If they are exactly the same, I do not understand then why do they have different names. In general, Voltcraft whose firm?. I know nothing about it. Clean the contacts already tried - did not help.

author: Wytnucls
author_rank: Super Contributor
timestamp: September 30, 2012, 09:38:27 am
content: Quote from: h1386343 on September 30, 2012, 08:15:30 amYes, cleaning the zebra strip is a good start, otherwise check the connections on the display driver pins.I have the B and D models. I believe the 71E circuit board is quite different, but if you can post the schematic here, it would still be beneficial for some users, I'm sure.

author: Wytnucls
author_rank: Super Contributor
timestamp: September 30, 2012, 09:44:18 am
content: Voltcraft, as far as I know, is a German company; they sell other manufacturer's meters under their own name, mostly through Conrad. Extech, Uni-T, etc...

author: h1386343
author_rank: Regular Contributor
timestamp: September 30, 2012, 09:47:46 am
content: Quote from: Wytnucls on September 30, 2012, 09:38:27 amWell, then, I'll add to the forum circuit from voltcraft 940.

author: h1386343
author_rank: Regular Contributor
timestamp: September 30, 2012, 09:53:59 am
content: But the photo UT71E. Photos taken from another forum.

author: Wytnucls
author_rank: Super Contributor
timestamp: September 30, 2012, 10:45:11 am
content: Well, in the end, the board is very similar to those on the other models.The 71E has an extra uC (U9) under the LCD screen ( TI M430FE425), probably for W computations.http://www.ti.com/lit/ds/symlink/msp430fe425.pdfThe other one is TI M430F149, aka TI LSD0007, on the other side of the board, like the 71D model (16-Bit Ultra-Low-Power Microcontroller, 60 kB Flash, 2KB RAM, 12 bit ADC, 2 USARTs, HW multiplier).Same Holtek 32x4 LCD controller too:http://reverse.0cpm.org/grandstream/datasheet/HT1621.pdf

author: h1386343
author_rank: Regular Contributor
timestamp: October 01, 2012, 04:59:38 am
content: In general, we have got to repair UT71E. For a long time we were looking for the cause of failure, until I came up with an idea. Namely, the soldering station properly warmed fee. Hope was not enough, it would work, but it worked. All segments of the work. It now remains - checking and, if appropriate, and calibration. But I think it still needs calibration.

author: h1386343
author_rank: Regular Contributor
timestamp: October 01, 2012, 01:01:55 pm
content: My friends. There is another problem. On a range of 'resistance' Extremely lying. For example if the 1k resistor, METER shows 0.4 ohms if 10k, it shows 8 ohms. Who can tell what resistors affect the accuracy of the resistors?

author: h1386343
author_rank: Regular Contributor
timestamp: October 02, 2012, 03:17:46 pm
content: Does not anyone know what resistors are responsible for the accuracy in the range of "resistance."

author: Wytnucls
author_rank: Super Contributor
timestamp: October 06, 2012, 09:04:25 am
content: Here is a picture of my Uni-T 71B, modified with a 10A Bussmann BS 1362 ceramic fuse. I'll install a proper HRC DMM fuse when I get one from Jaycar in Australia. Possibly a Fluke one if it fits, otherwise a SIBA DMI fuse.The 500mA glass fuse is more difficult to replace, as there is less space on the board to install the fuse clamps.