EEVblog 121GW Multimeter Issues

[Fungus]

Hello — I'm seeing a problem where the 121gw shows incorrect frequency period. From my waveform generator I feed in a 0-5 V square wave at 1 kHz with a 50% duty cycle. The meter correctly shows a 1.0000 kHz for frequency, but a period of half the expected value at 0.4999 ms. Oddly adjusting the duty cycle changes the period measurement as well. With a 70% duty cycle at 1 kHz the period now reads 0.6999 ms. It seems to be missing the later half of the waveform in the period measurement.

Maybe the number on screen is "duty cycle". 

[jeraymond]

Hello — I'm seeing a problem where the 121gw shows incorrect frequency period. From my waveform generator I feed in a 0-5 V square wave at 1 kHz with a 50% duty cycle. The meter correctly shows a 1.0000 kHz for frequency, but a period of half the expected value at 0.4999 ms. Oddly adjusting the duty cycle changes the period measurement as well. With a 70% duty cycle at 1 kHz the period now reads 0.6999 ms. It seems to be missing the later half of the waveform in the period measurement.

Maybe the number on screen is "duty cycle". 

Well, yes the bug seems to be that the period measurement mode is showing duty cycle instead. In the Hz dial position I press MODE once and get to 0.6999 ms (this should be period) a second press I get to the duty cycle measurement where it shows 70.0.

[bicycleguy]

The latest manual (March 2020) on page 48 says:

The following modes are available on the frequency range :
1. Frequency
2. Pulse width
3. Duty Cycle

However, every where else in the manual they call 'Pulse width' 'Period'.  So it works as I like and the manual is wrong.  I think this was reported years ago.

[markeng]

Hey Dave! Regarding: https://www.eevblog.com/forum/testgear/eevblog-121gw-multimeter-issues/msg2792850/#msg2792850

I sent you couple emails but haven't heard back. I have a broken input jack on my 121GW multimeter SN: 180807570, which is out of the affected range. Can you send me a replacement input jack, I would be happy to pay for it. I couldn't find a replacement jack anywhere online, if you don't want to send one out could you point me in the direction of where I can buy one?

Does anyone else on the forum know of a place to purchase a replacement input jack for my 121GW multimeter?

Thanks so much!

[EEVblog]

Hey Dave! Regarding: https://www.eevblog.com/forum/testgear/eevblog-121gw-multimeter-issues/msg2792850/#msg2792850

I sent you couple emails but haven't heard back. I have a broken input jack on my 121GW multimeter SN: 180807570, which is out of the affected range. Can you send me a replacement input jack, I would be happy to pay for it. I couldn't find a replacement jack anywhere online, if you don't want to send one out could you point me in the direction of where I can buy one?

Does anyone else on the forum know of a place to purchase a replacement input jack for my 121GW multimeter?

Thanks so much!

I don't see any message from your email address.
I'll send you an email.

[DylanW]

Hi all,

I went to replace the batteries in my 131GW and discovered that two had leaked, badly corroding the terminals. I was wondering if there was a source I could purchase some replacement terminals from?

The serial number is 171202952 if that helps.

Cheers!

[oliv3r]

Hey all,

I have an early 1.21GW with software version v2.05 (haven't checked if there's an update yet :p)

I also have a 2 year old fluke 115. I tried to measure some CT Coils with built in burden resistor, to check its resistance. This is where things got funny (due to my lack of understanding). I would have expected to get the value of the copper windings, in parallel to the resistor. Not sure _what_ I'm getting though; as I see a about 8 or 9 ohms, that are constantly changing on the display (walking up, walking down) over 1 or 2 ohms or so on the 1.121 whereas the fluke (with much less digits mind you) was showing something like 20 ohms. Pretty big difference I would think. Could this be caused by _how_ things are measured? Is the coil of influence? I can imagine that the fact that we are measuring ferrite wound coils, an inductor in fact, could throw things off as the inductor 'buffers' energy, and releases it again?

[toomuchesr]

Hi Dave!

Mine has the "cracked plug" problem as well. Serial starts with 1808071__

I would be happy to know which replacement part I could source and where (I'm in the EU).

Thank you!

BR, Hendrik

[J-R]

My 121GW does generate a few changing voltages during resistance auto-ranging.  I think it was 0.2V, 1V and 2V at least.  But otherwise it's pretty stable once in a specific range as best I could tell on my scope without spending too much time to block out noise.

I wonder if the coil is picking up some EMI?  Can you shield it to see if the behavior changes?

[toomuchesr]

Hi Dave!

Mine has the "cracked plug" problem as well. Serial starts with 1808071__

I would be happy to know which replacement part I could source and where (I'm in the EU).

Thank you!

BR, Hendrik

🥺 Dave? Or anyone else who knows which part to source?

[oliv3r]

The changes I see are very 'sine-ey' so that wouldn't be a supprise. The difference between the two multimeters is a big supprise however, which I care more about?

[EEVblog]

Hi Dave!

Mine has the "cracked plug" problem as well. Serial starts with 1808071__

I would be happy to know which replacement part I could source and where (I'm in the EU).

Thank you!

BR, Hendrik

🥺 Dave? Or anyone else who knows which part to source?

Send me an email with your address and I'll send you one.

[uer166]

Wow so first the A/mA jacks cracked at top, now entire Volt jack sleeve came off from next to no use of meter 

See attached..

Bad batch, see here:
https://www.eevblog.com/forum/testgear/eevblog-121gw-multimeter-issues/msg2792850/#msg2792850

It happened again with the replacement as well after a few months. Is this maybe just a general problem with these input not supporting say unshrouded banana jacks? I do sometimes use Pomona bananas in the meter. @Dave maybe you can setup a store item for replacement jack assemblies?

[snoozer]

Hello,

I am glad I found this in the forum, I was a bit puzzled why the sleeve around the positive V terminal broke cause I don't do anything mobile or off the bench and always use test leads with the shround around the conductor.Is that input terminal assembly still available for replacement or do I have to send my 121GW to the supplier to get fixed ? I bought mine from Welectron with an invoice date of 28/08/2019.

Kind Regards
Jan P.

[mbalmer]

I'm having an issue with my 121GW that I can't seem to figure out.

Firmware is v2.05, S/N is 210403337.

When trying to measure frequency, the meter just seems to ignore any signals it's given. I initially noticed it when I was trying to measure the frequency of a composite sync signal to make sure that it was properly tuned, and the meter was constantly reading zero. I then tried attaching the leads to my HP function generator with a 1KHz square wave and the meter just acted like it wasn't there.

It's almost like the leads are completely disconnected when the meter is set to Hz mode. All of the other modes work fine, but for whatever reason, I can't get the thing to respond when measuring frequencies.

Any ideas?

[AVGresponding]

I'm having an issue with my 121GW that I can't seem to figure out.

Firmware is v2.05, S/N is 210403337.

When trying to measure frequency, the meter just seems to ignore any signals it's given. I initially noticed it when I was trying to measure the frequency of a composite sync signal to make sure that it was properly tuned, and the meter was constantly reading zero. I then tried attaching the leads to my HP function generator with a 1KHz square wave and the meter just acted like it wasn't there.

It's almost like the leads are completely disconnected when the meter is set to Hz mode. All of the other modes work fine, but for whatever reason, I can't get the thing to respond when measuring frequencies.

Any ideas?

Is the signal level high enough?

[joeqsmith]

Any ideas?

Maybe put a cap in series with the meter to strip any DC bias.  It's been a few years since I looked at this meter.  I don't remember running into any problems with the frequency function but it seems like it was limited to a MHz. 

[EEVblog]

I'm having an issue with my 121GW that I can't seem to figure out.
Firmware is v2.05, S/N is 210403337.
When trying to measure frequency, the meter just seems to ignore any signals it's given. I initially noticed it when I was trying to measure the frequency of a composite sync signal to make sure that it was properly tuned, and the meter was constantly reading zero. I then tried attaching the leads to my HP function generator with a 1KHz square wave and the meter just acted like it wasn't there.
It's almost like the leads are completely disconnected when the meter is set to Hz mode. All of the other modes work fine, but for whatever reason, I can't get the thing to respond when measuring frequencies.

Maybe a signal level issue? I don't recall what the minimum signal level is, but it's not designed for low level signals.

[oliver602]

Are the replacement jacks still available? I've been using Probe Master 8017S test leads and part of the plastic sleeve broke off from the +volts jack. Emailed Dave a while back but didn't get a response.

[EEVblog]

Are the replacement jacks still available? I've been using Probe Master 8017S test leads and part of the plastic sleeve broke off from the +volts jack. Emailed Dave a while back but didn't get a response.

Emailed.

[hainjedaf]

Are the replacement jacks still available? I've been using Probe Master 8017S test leads and part of the plastic sleeve broke off from the +volts jack. Emailed Dave a while back but didn't get a response.

Emailed.

Same question:

My input jacks on my 121 GW are busted because I used probemaster probes and banana jacks directly in the meter sockets.
Mine is a 2019 built 121gw qith very brittle plastics on the input jacks.

I can't seem to order them from UEI or Brymen EU.

I'd be glad to pay the postage to get my meter repaired.

[EEVblog]

Are the replacement jacks still available? I've been using Probe Master 8017S test leads and part of the plastic sleeve broke off from the +volts jack. Emailed Dave a while back but didn't get a response.

Emailed.

Same question:

My input jacks on my 121 GW are busted because I used probemaster probes and banana jacks directly in the meter sockets.
Mine is a 2019 built 121gw qith very brittle plastics on the input jacks.

I can't seem to order them from UEI or Brymen EU.

I'd be glad to pay the postage to get my meter repaired.

Email me your address and phone number.

[hainjedaf]

To which email address?

If i click email in the forum, i simply don't get an email address.

I also mailed to your eevblog.com contact address but no reaction yet.

My email is my username at gmail.com

Kind regards

[tautech]

To which email address?

If i click email in the forum, i simply don't get an email address.

I also mailed to your eevblog.com contact address but no reaction yet.

My email is my username at gmail.com

Kind regards

Yep, it's busted. Try a PM instead.

[hainjedaf]

Thanks for the tip.

Have done pm and message to the eevblog.official email