Problems with EEV 121GW Multimeter. - Page 1
Forum section: electronics / testgear

author: duodiode62
author_rank: Contributor
timestamp: December 14, 2020, 12:29:39 am
content: Hello all.I'm having trouble with my 121GW multimeter. When set to the diode test function, I get the "Lead" error. This doesn't happen all the time; about half the time. When it does happen, no amount of turning the multimeter off and on or changing ranges fixes it. Does anyone know of this problem, and how to fix it? The multimeter is less than a year old.Regards, Stuart

author: bc888
author_rank: Regular Contributor
timestamp: December 14, 2020, 03:30:34 am
content: Not posted at these locations?https://www.eevblog.com/forum/testgear/eevblog-121gw-discussion-thread/andhttps://www.eevblog.com/forum/testgear/eevblog-121gw-multimeter-issues/

author: DaJMasta
author_rank: Super Contributor
timestamp: December 14, 2020, 04:00:31 am
content: First off, you do have the leads in the correct positions, right? Positive lead to the V/Ohm/Diode/Temp position and negative to black?If you do, sounds like it's an issue with the probe detection in the A/uA jacks. I don't know what mechanism they use, but I'm assuming it's like an audio jack with sense and it's pushing a contact open when a probe is inserted, in which case maybe that is bent or damaged.

author: duodiode62
author_rank: Contributor
timestamp: December 14, 2020, 11:52:22 pm
content: Yes, I searched for a specific discussion location for the 121GW but nothing came up, so I assumed that it must've been taken down. Unfortunately, the search doesn't seem to work very well.

author: duodiode62
author_rank: Contributor
timestamp: December 14, 2020, 11:53:12 pm
content: Yes. The probes are in the correct positions.

author: EEVblog
author_rank: Unknown
timestamp: December 15, 2020, 02:45:45 am
content: Very strange fault.A far out there idea - given that the lead detection comes from a high impedance input on a split jack of the current inputs, maybe it's some gross nearby EM source?A bad connection in the dectection input circuit would make it not work at all, not make it false trigger, so I'd rule out that.There have been issues with the input jacks, but that's cracking due ot brittle plastics, and to my knowledge no shorts between the contacts.I'd usually replace it, but unfortunately it's copletely out of stock due to component shortages for the next couple of months.

author: J-R
author_rank: Super Contributor
timestamp: December 16, 2020, 03:23:44 am
content: Do you get the Lead error with the selector in the Volts positions? If it does it in the Diode position but not Voltage, then perhaps the jacks themselves could be ruled out. Maybe inspect the selector contacts and associated area on the PCB.

author: duodiode62
author_rank: Contributor
timestamp: January 28, 2021, 04:55:23 am
content: Sorry for not getting back sooner. The problem is worse now, and the multimeter unusable. I've e-mailed the supplier, but they did not get back to me. Help please. I feel I will have to get in touch with consumer affairs if this is not resolved.

author: bc888
author_rank: Regular Contributor
timestamp: January 29, 2021, 05:20:50 am
content: Sorry to hear of your issues. Who was the supplier you emailed? FYI, Dave had earlier noted he was going on Vacation. If he was the recipient of your email, please give him some time.

author: EEVblog
author_rank: Unknown
timestamp: January 29, 2021, 06:06:39 am
content: Is there any contaminent inside the connector jacks?Maybe clean them out with isopropyl. Even a low leakage inside one of the current jacks could cause leakage and activate the high input impedance detection circuit.

author: duodiode62
author_rank: Contributor
timestamp: February 01, 2021, 11:10:14 pm
content: Thanks for your reply. I finally found my receipt, and my multimeter is unfortunately out of warrantee. Looks like I'm on my own. Yes, I'll have to pull it apart and see if I can clean the plug detection contacts.Frustrating though, to have such an expensive meter fail so quickly.Stuart

author: Kean
author_rank: Unknown
timestamp: February 07, 2021, 11:36:38 am
content: @OP this document with dissassembly instructions was written for the early batch with some tolerance issues related to the rotary switch.https://www.eevblog.com/files/How%20to%20Replace%20121GW%20Rotary%20Switch-180411.pdfI don't think that issue applies to your unit, but it could have a similar issue affecting switch contacts. Maybe give the contacts a clean/tweak.

author: duodiode62
author_rank: Contributor
timestamp: February 08, 2021, 05:50:49 am
content: Hi JR and others. Thanks for your help. I should be able to pull it apart enough to examine the plug detector with the disassembly instructions, when I get time. I tried pulling it apart; undid all the screws I could find, but it is still stuck together. Don't want to break anything. I'll get back to you.