EEVblog Electronics Community Forum
Products => Test Equipment => Topic started by: duodiode62 on February 07, 2021, 05:21:40 am
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Hi all. It looks like I am on my own with this failure. I suspect that one or more switches that detect the probe positions have failed, rendering the multimeter useless. I've tried pulling it apart, to see if I can get to the switches, but I can't get the board out. Does anybody know where I can get service information for it; specifically dismantling instructions and a circuit diagram?
Cheers, Stuart
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There are some good photos here that might help: https://lygte-info.dk/review/DMMEEVBlog%20121GW%20UK.html (https://lygte-info.dk/review/DMMEEVBlog%20121GW%20UK.html)
It should be pretty straight-forward: 2 screws for the battery cover, 4 screws for the back cover (and one clip, careful!), then 2 black screws on the PCB. One is partially under the 10A fuse. Don't remove the 4 screws for the display.
At that point the PCB should come out with just a little bit of pulling and wiggling.
While all the jacks are split physically, only the amperage jacks have any detection. It's not a physical, insertion switch. It's a detection circuit.
Check out the schematic here: https://www.eevblog.com/wp-content/plugins/download-attachments/includes/download.php?id=11618 (https://www.eevblog.com/wp-content/plugins/download-attachments/includes/download.php?id=11618)
The portion of interest would be the "Input Warning Circuit".
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As a side note, you already have another thread for this issue: https://www.eevblog.com/forum/testgear/problems-with-eev-121gw-multimeter/ (https://www.eevblog.com/forum/testgear/problems-with-eev-121gw-multimeter/)
I requested the moderators merge it.
You did not respond to the suggestions made in the other thread. Can you provide an update on whether you tried them or not or what other steps you may have taken to correct the issue?