maynuo m9710 dc load problems - Page 1
Forum section: electronics / general

author: radiogeek97
author_rank: Regular Contributor
timestamp: June 13, 2015, 02:23:31 pm
content: FolksI have a m9710 dc load that i recently purchased and I am having issues getting it to work. I am wondering if any of you have had similar problems.What it is doing is that when i try to set it for a CC (constant current mode) it reads out "unreg" Nothing i try gets the unit to respond and go into CC mode. I have read the (poorly written) manual over and over and cant figure this out. I have tried several good bench top supplies including my dp832 and this just wont respond. The unit will pass the internal self tests and it will go into constant voltage mode. I contacted the seller and they say ship it back to chinaAnybody else with one of these units that can point me in the right direction. I have emailed sales and service several times maynuo as well and have had no reply in over a week

author: jadew
author_rank: Frequent Contributor
timestamp: June 13, 2015, 02:27:52 pm
content: Does it draw any current?

author: radiogeek97
author_rank: Regular Contributor
timestamp: June 13, 2015, 02:45:21 pm
content: once in a great while it will flutter between "unreg" and cc my dp832 will show wildly fluctuating readings.Oh and onother thing this I noticed, the maynuo appears to read about .4 volts low when compared to what my dp832 is feeding it. I send in 12vdc from the rigol and the maynuo reads 11.6v. i have checked thei over the entire range of my dp832's output capacity. I have also cehecked that the dp832 is accurate with 2 dmm's

author: con-f-use
author_rank: Unknown
timestamp: June 13, 2015, 02:52:22 pm
content: Sound's like yours is broken. My 9812 reads a tiny bit low, too, even with short heavy cables and the sense wires of my supply directly at the load's input but its <10 mV @ 12V, 1A and it regulates very well. Without sense wire's bad cabeling might account for 0.4V voltage drop but not for a non-working CC mode.

author: Fraser
author_rank: Super Contributor
timestamp: June 13, 2015, 03:19:11 pm
content: Not wishing top bring bad news but when I investigated the M9710 I discovered that it is a 'China only' non export model. The reasons given for this included lower quality control, cheaper components and higher failure rate. The M9712 is the export grade model but more expensive as a consequence of better spec components and QC. It is cheap to return an M9710 within China but the OEM does not want warranty claims outside China as it gets expensive in postage and the customer gets narked. The M9712 has a good reliability record. I have yet to see any evidence of higher failure rates in the 9710 but there quite a lot of discussion on English and Chinese electronics forums.It would be worth carefully inspecting the build quality of your 9710 and correct any poor quality found. Sorry I cannot help on the diagnostics of your problem though.The 9710 model has no support outside China so I doubt the OEM will be much help to you. They specifically tell their agents to not sell that model overseas.RegardsAurora

author: radiogeek97
author_rank: Regular Contributor
timestamp: June 13, 2015, 03:19:54 pm
content: i figured this thing was buggy, I mean if i can figure out how to use my dsa-815 I didnt think i was doing much wrong here in this case. I guess I can void the warranty and crack this open and take a poke arround, Not as if i am going to pay 100usd to ship this back to china. I should have purchased one from t-equipment but they are soo much more. Penny wise and pound foolish on my part. Thank you for the speedy reply

author: radiogeek97
author_rank: Regular Contributor
timestamp: June 13, 2015, 03:24:09 pm
content: auroraThanks I wasnt aware of the export only status of the 9710 and lack of support. I guess i can try buyier protection or call my credit card company and see what i find out. I mean nowhere in the add does it indicate not for export

author: Fraser
author_rank: Super Contributor
timestamp: June 13, 2015, 03:27:59 pm
content: Good luck with the repair.Would you be able to post pictures of the PCBs as others on this forum have the M9812 and they may be able to tell you which, if any components are different make/quality etc. You may be able to upgrade any poor quality parts like capacitors, transistors and MOSFETs. I can't imagine that the differences are that great.You could list the OEM symbol of the key parts manufacturers within your unit and maybe a helpful forum member will compare them to a M9812 ?I believe that there are already pictures of the MS9812 PCB's on this forum.Aurora

author: radiogeek97
author_rank: Regular Contributor
timestamp: June 13, 2015, 04:32:28 pm
content: sure that's the least i can do for the folks here. once the baby naps i'll snap a few

author: con-f-use
author_rank: Unknown
timestamp: June 13, 2015, 04:36:29 pm
content: Might just be a bad solder joint or a faulty component.