EEVblog 121GW Multimeter Issues

[jcosper]

Hello all,

My GW121 recently starting misbehaving. I pulled it out after a 2 week vacation, and now it beeps constantly and displays "LEAD" in resistance/capacitance/continuity modes (but diode mode doesn't beep and seems to work). It also happens in voltage measurement mode, and some current measurement modes, but not all.

I changed the batteries (standard cells) with no change. I tried different probes (and no probes) with no change. Fuses test good. My meter has FW 2.05 sn 210403113. I didn't find mention of this code in the manual, and no relevant hits searching. Any thoughts? AFAIK, it was fine when I stored it away after last use, but something gave up.

Thanks!
Jay

[J-R]

It is odd that it doesn't beep in diode mode.
What current modes does it beep?

Typically the first step is to thoroughly clean the A and mA jacks.  Has it been used in a dirty environment?
Beyond that you could return it if it's still under warranty.
If not, disassemble and inspect the "Input Warning Circuit" as shown on the schematic.  The resistances involved are pretty high, so again I'd look for some contamination as the first suspect.
https://www.eevblog.com/wp-content/plugins/download-attachments/includes/download.php?id=11618

[EEVblog]

Typically the first step is to thoroughly clean the A and mA jacks.  Has it been used in a dirty environment?

Yes, always the first step.

[jcosper]

It is odd that it doesn't beep in diode mode.
What current modes does it beep?

Typically the first step is to thoroughly clean the A and mA jacks.  Has it been used in a dirty environment?
Beyond that you could return it if it's still under warranty.
If not, disassemble and inspect the "Input Warning Circuit" as shown on the schematic.  The resistances involved are pretty high, so again I'd look for some contamination as the first suspect.
https://www.eevblog.com/wp-content/plugins/download-attachments/includes/download.php?id=11618

Thanks for the input. It beeps in uA but not A/mA (shows 0.07mA with nothing connected). I really only use it in my home lab. I guess I'll start tearing it apart and give it some tlc. I have owned it for a couple of years now.

[J-R]

In that case I think I would focus on the A 500mA jack first.
No need to open it up for the cleaning.  Just scrub the inside of the jack to start.

[jcosper]

In that case I think I would focus on the A 500mA jack first.
No need to open it up for the cleaning.  Just scrub the inside of the jack to start.

I cleaned the jacks and now Ohm/continuity/A/uA don't beep and display "LEAD" but capacitance and voltage measurements still do. I'll scrub it some more to see if I can get all functionality to recover. 

[snoozer]

Hi,

I have one of the plastic ferrules around the input jack for the positive Volt, Ohm etc broken, I found it stuck in the test lead. I wonder are the replacement terminal still available ? I am not using the meter on the road etc, its exclusively used on the bench in my hobby lab. I don't post the SN of the 121GW here but I can ofc on request give it. I also have the invoice of Welectron where I bought the meter on the 28/08/2019.

Kind Regards
J. Paulini

[J-R]

Hi,

I have one of the plastic ferrules around the input jack for the positive Volt, Ohm etc broken, I found it stuck in the test lead. I wonder are the replacement terminal still available ? I am not using the meter on the road etc, its exclusively used on the bench in my hobby lab. I don't post the SN of the 121GW here but I can ofc on request give it. I also have the invoice of Welectron where I bought the meter on the 28/08/2019.

Kind Regards
J. Paulini

E-mail or PM Dave for info on this.

[EEVblog]

I have one of the plastic ferrules around the input jack for the positive Volt, Ohm etc broken, I found it stuck in the test lead. I wonder are the replacement terminal still available ? I am not using the meter on the road etc, its exclusively used on the bench in my hobby lab. I don't post the SN of the 121GW here but I can ofc on request give it. I also have the invoice of Welectron where I bought the meter on the 28/08/2019.

Because you bought it from Welectron, they will have to handle support, so I can't send a free replacement, but if you want to pay for shipping I can send one. I'm not sure if they offer the jack.

[snoozer]

Hi,

thanks for getting back to me. I was not even considering a free of charge spare part, I am happy to pay for it. How shall we proceed with this, I am not happy putting my address etc. public. Shall I PM you or will you PM me ?

Thanks
J. Paulini

[robert.rozee]

I have one of the plastic ferrules around the input jack for the positive Volt, Ohm etc broken, I found it stuck in the test lead [...] I bought the meter on the 28/08/2019.

this seems to be an increasingly common occurrence with multimeters and other test equipment, where mechanical components are failing within a few years of purchase. yet i use older gear dating from the 1990's that have been subject to significant wear-and-tear without bits 'breaking off'. i just had a look at an HP34401A and see it has solid copper tubes where the shrouded banana plugs fit in; a Fluke 8842A has machined brass with a chrome plating.

i'm not wanting to criticize Dave, but...

1. it is not fair to expect better from modern manufacturers? how functional will (for example) a 121GW be 10 years from now? or a Fluke 87V, that i believe suffers similar failures.

2. why hasn't someone come up with a retrofit for such pieces of relatively expensive gear? sockets made out of solid copper that can be fitted in place of the current ones that seem to keep failing. it seems that something could be turned out by an automatic lathe for minimal per-piece cost.

Dave: my apologies, i think you are doing a sterling job helping out owners of the affected gear. my criticisms are for the manufacturers who must surely be aware of the failings.


cheers,
rob   :-)

[J-R]

I have one of the plastic ferrules around the input jack for the positive Volt, Ohm etc broken, I found it stuck in the test lead. I wonder are the replacement terminal still available ? I am not using the meter on the road etc, its exclusively used on the bench in my hobby lab. I don't post the SN of the 121GW here but I can ofc on request give it. I also have the invoice of Welectron where I bought the meter on the 28/08/2019.

Because you bought it from Welectron, they will have to handle support, so I can't send a free replacement, but if you want to pay for shipping I can send one. I'm not sure if they offer the jack.

But what is the arrangement for the serial numbers that had the known issue (if snoozer's DMM S/N is within that range)?  Is Welectron handling those as well?  Since it was purchased in 2019...

[EEVblog]

thanks for getting back to me. I was not even considering a free of charge spare part, I am happy to pay for it. How shall we proceed with this, I am not happy putting my address etc. public. Shall I PM you or will you PM me ?

Send me an email.

[EEVblog]

But what is the arrangement for the serial numbers that had the known issue (if snoozer's DMM S/N is within that range)?  Is Welectron handling those as well?  Since it was purchased in 2019...

I have no insight into what Welectron do, they buy the meter direct from Kane Test and handle their own support.