[Repair] Current reading error with DSN-VC288 (100V 10A Voltmeter Ammeter) - Page 1
Forum section: electronics / beginners

author: danon.spy
author_rank: Newbie
timestamp: March 18, 2018, 12:02:54 pm
content: Hi DIYer,I have come across this issue. When I tried to make a power supply using some cheap DC to DC converter and a volt+amp meter, the current meter show an error as in the pictures. It show stable ~15.5A even with or without load. I don't know what have I didWhen I shorted the little current shunt with the LM358 opamp (pin 2 or 3 or 4), it seems to fix the issue. But I don't know if I permanently do that, would it destroy that meter? Will it have any negative effect?Images (click on image for original size):

author: BrankoMN
author_rank: Newbie
timestamp: March 23, 2018, 08:31:17 pm
content: https://www.ittsb.eu/forum/index.php?topic=1351.0

author: danon.spy
author_rank: Newbie
timestamp: March 24, 2018, 09:58:48 am
content: Quote from: BrankoMN on March 23, 2018, 08:31:17 pmThank you so much for that link.I am reading this and test on my meter with the RESET trick, will update for the result.

author: jorgemef
author_rank: Regular Contributor
timestamp: October 19, 2022, 12:14:20 am
content: After some fighting with a latest one from AliExpress I concluded:Best linearity is achieved by using external supply.If using same supply leave ground from voltage plug floating else will add a lot offset impossible to compensate with potenciometer.The best linearity I achieved was by incrementally regulating the potenciometer and reset the module to compensate offset for potenciometer setting unloaded. I used same power supply so with 10ma I read 8ma and with 1,5A I read 1,53A. With external supply I achieved 10mA as 10mA and 5A as 5,01A.I opted for same supply as is enough for my needs and didn't wanted to buy another transformer just to power it up as I am using two independent units in a same power supply to have independent rails. Have small switching PSU Wich I could use but they introduce EMI in the output through the amperimeter.

author: jorgemef
author_rank: Regular Contributor
timestamp: October 22, 2022, 04:48:04 pm
content: Hello.Any bether unit that fits same layout or suggested seller that sell a good version of this meter?Unfortunately one of my units broke during reset. Not sure if is because I reseted with it on, but had done it before without problems. This time microcontroller and LDO let magic smoke out.I was powering them with 28V. Maybe was too much.Will look for a new unit to fit to my almost finished dual rail power supply. If I can find something better than my crippled version will go for it.Cheers,Jorge

author: BrankoMN
author_rank: Newbie
timestamp: October 22, 2022, 08:24:19 pm
content: Try thishttps://www.aliexpress.com/item/1005003786622190.html?spm=a2g0o.order_list.0.0.21ef1802VVJUFkand read carefully product description. Here is a description of how to set it uphttps://youtu.be/NxnhyCE43Vc. I bought one and it works great.

author: xavier60
author_rank: Super Contributor
timestamp: October 23, 2022, 10:52:57 am
content: I wish the display refresh was really 300ms as advertised instead of really being 1000ms.Those 4 digit meters have auto-zeroing on the current meter, so the reading is very stable.

author: smd_hunter
author_rank: Newbie
timestamp: October 24, 2022, 02:18:12 pm
content: Quote from: jorgemef on October 19, 2022, 12:14:20 amThanks for the idea Jorge! I have two DC-DC source modules with segment display to see voltage and current, one of them has a lm358, the other one does not. The one with the op-amp differs the current as it happens to the OP. When I get home I will do some tests.