Amprobe 37XR-A Reading 2-3x Higher AC/DC Voltages - Page 1
Forum section: electronics / repair

author: BigJug
author_rank: Newbie
timestamp: July 02, 2023, 04:49:52 pm
content: Hello Everyone - I'm new to the forum and was hoping someone may have some insight as to whats going on with my Amprobe Multimeter. I use a 37xr-a for work, and typically use the VAC measurement about 90% of the time, with the odd VDC and Continuity measurements also. The equipment I'm testing is usually has an output in the range of 60-90VAC.About a week ago I went to make a reading (expecting ~90VAC) and was getting 175V. BTW - I'm in Canada (Ontario) and we use a ~120V system. So this 175V completely through me off, and because I didn't have another meter to verify, I had to stop. Next day went back with a buddy and using his meter and a 2nd meter that I brought, and was getting 87V.Tested at a main A/C outlet, and I was getting somewhere around 305V (should be getting between 110-125v)?? I'm testing a 9volt battery, and getting 45VDC!. Meter kept in pristine condition and hasn't taken any damage or abuse. All functions seem to "engage" and appear to be working, but just wrong! I thought this was supposed to be a high quality meter...

author: Grandchuck
author_rank: Super Contributor
timestamp: July 02, 2023, 05:55:33 pm
content: There might be a clue here:https://www.bing.com/videos/search?q=amprobe+38xr+calibration&docid=603504026800901792&mid=786BD97F8D5D00272EFC786BD97F8D5D00272EFC&view=detail&FORM=VIRE

author: BigJug
author_rank: Newbie
timestamp: July 03, 2023, 01:12:43 am
content: Much Thanks Grandchuck. Sadly I do not have a power supply to calibrate with.

author: J-R
author_rank: Super Contributor
timestamp: July 03, 2023, 02:40:57 am
content: As mentioned in the comments for that video, the procedure shown is not necessarily correct.If everything is so far off, I would suspect some internal damage to some component. First try to get it replaced under warranty, then if that fails, open it up and look for damage.Can you test all the other functions? Resistance, current, etc.?

author: floobydust
author_rank: Super Contributor
timestamp: July 03, 2023, 03:25:53 am
content: Take it apart, post pics. Readings way higher than expected are an uncommon problem.It sounds like a bad solder joint on the resistor divider chain, as a wild guess. Bump it around a bit as well, see if it moves or changes the readings.

author: BigJug
author_rank: Newbie
timestamp: July 06, 2023, 09:19:44 pm
content: Yes readings were WAY higher than normal. Bumping it around did not seem to change much. Going back to when I was using it in the field, I noticed that even testing the same point, I got different readings after turning the power off, and then back on again - EX: was expecting ~87V, was actually getting 175V, turned the power off, then back on again, and it jumped up to 204V. Was testing a 9 volt battery, was getting 45V, then next day was getting 25V.Meter was issued to me by my workplace, so after notifying them of the issue, they promptly requested me to hand it in and am currently waiting on a replacement unit. Its a fairly large company, and I doubt they will spend any time troubleshooting it themselves, but they didn't want to take any risks with Health & Safety once it was reported as defective. It will likely be replaced with the same make & model - hopefully it will last longer than the 2 or so years that I've had this original.I did not have a chance to open it to take pictures, my apologies everyone, but a HUGE thank you to everyone assisting me in the matter!