Fluke 37 refurbishing - Page 1
Forum section: electronics / testgear

author: saraht
author_rank: Newbie
timestamp: October 10, 2013, 11:55:29 pm
content: Hi folks,I just picked up four Fluke 37s pretty cheaply, and am in the process of refurbishing them. Three of the four were really nice, a couple needed fuses replaced. One has an iffy display -- it is getting dim, but actually looks fine if you look at the meter at an angle from below, rather like the angle adjustment is off. Only thing is -- my Google-fu is failing me. I can't find a service manual anywhere online. The user manual is available, but it doesn't have schematics etc. Has anyone got one? Or a calibration manual?I tore down the one of the four that was in the worst state to try to figure out what could be tweaked, hoping that one of the pots might be a display angle/brightness adjustment, but nothing made a difference. I certainly messed up the cal on that one, but I did figure out which pot was the voltage trim adjustment, so I was able to set it up nicely (and the other three) against my voltage standard. None of the other pots seemed to affect the current reading, so I'm assuming a precision shunt must be in there, or something?Anyway, any help or advice would be greatly appreciated.SarahPS: New to the board. I've been watching Dave's videos for a while -- he inspired me to buy a LeCroy 9370M for not much money on eBay. After $60-worth of parts (5 new rotary encoders and a fan) it works beautifully!

author: retiredcaps
author_rank: Super Contributor
timestamp: October 11, 2013, 06:25:24 am
content: Quote from: saraht on October 10, 2013, 11:55:29 pmHave you tried taking it apart and cleaning the zebra strip on the lcd? Something like this?http://mrmodemhead.com/blog/fluke-8x-faded-lcd/

author: retiredcaps
author_rank: Super Contributor
timestamp: October 11, 2013, 06:35:01 am
content: A service manual for the 37 does exist as shownhttp://www.ebay.com/itm/390438283177but I can't find an electronic copy yet.PS. The Fluke 27 has the same look and feel as the 37. Perhaps the internals of the 27 is similar enough to the 37 that you can use the Fluke 27 service manual? I would love to see pictures of the insides of the 37!

author: ModemHead
author_rank: Frequent Contributor
timestamp: October 11, 2013, 12:40:25 pm
content: From outward appearances, it looks like the 37 is really a 27, with the features rotated 90 degrees and re-packaged into a lunchbox. The 27 documentation will probably be helpful if the real deal cannot be located. I'd be interested in seeing inside as well.

author: saraht
author_rank: Newbie
timestamp: October 17, 2013, 04:38:32 am
content: Yeah, as best I can tell, the 37 is the same BOM and circuit as the 27, but laid out differently.Anyway, I can report that of the four of them, I now have them all 100% working thanks to the help here. You're all awesome. Just sayin'. :-)So, of the four, the cal was off on 3 of the 4, compared to my Keithley 196 and my voltage standard, so I tweaked them and they were dead on in all the ranges. 3 of the 4 had blown fuses, 2 on the mA range and one on the A range, but no other damage. I replaced the fuses in 3 of them and they were good as new. I didn't have a spare for the huge chunky fuse in the 4th meter, so I'll have to order one, but I confirmed it working by bypassing the fuse temporarily (I was just running a few mA, no danger). The 4th one also had a weird dim/flickery display, which was fixed just by pulling everything apart and giving the contacts a bit of a clean. I did find one that was behaving weirdly with its amps range, but that turned out to be another bad connection that was fixed by cleaning up the contacts between the posts on the back of the front panel banana sockets and the PCBs. I also torqued the screws a bit harder. Anyway, all working now. I'm going to list them on eBay, anyway -- the 3 good ones tonight and the other one when the fuse shows up. I'll pull that one apart again for your entertainment, however. :-)Sarah

author: retiredcaps
author_rank: Super Contributor
timestamp: October 17, 2013, 06:18:05 am
content: Quote from: saraht on October 17, 2013, 04:38:32 amI have purchased a number of used and abused Flukes, all sorts of vintage, and while some of them were not "spot on" (1 to 2mV out on DCV), all were within its respective stated accuracy.So when you say the cal was off on 3 of the 4, were they actually out of their 0.1% DCV accuracy or just not "spot on".

author: Fungus
author_rank: Super Contributor
timestamp: May 28, 2016, 04:53:22 pm
content: I just bought one of these on eBay. It didn't arrive yet, but... any luck on the service manual?What fuses did you use? I hope my fuses are OK. They're expensive.

author: ziplock9000
author_rank: Regular Contributor
timestamp: December 22, 2016, 08:07:32 am
content: Quote from: Fungus on May 28, 2016, 04:53:22 pmDid you find it? I need to calibrate one I just got from eBay

author: w9gb
author_rank: Contributor
timestamp: April 28, 2020, 06:55:38 pm
content: Yes, the Fluke 37 is largely the Fluke 27 with different form factor and changes to match form factor.Look at the Zebra Strips and cleaning the tin-plated contacts (LCD and PCB) would be a first step.Here is an example, from 2019.http://anachrocomputer.blogspot.com/2018/11/fluke-37-digital-multimeter.htmlgood luck.gb