Heads up! Fluke 27/FM with box, TRMS, HV probe, and calibrated till 2016 - Page 1
Forum section: electronics / general

author: Lightages
author_rank: Unknown
timestamp: July 20, 2015, 05:28:00 am
content: http://www.ebay.com/itm/FLUKE-27-FM-27FM-MULTIMETER-MULTI-METER-WORKS-TESTER-RANGE-VOLTS-AMPS-PROBE-USED-/151741732003?pt=LH_DefaultDomain_0&hash=item23548314a3The prices on 27/FM are pretty variable. I have seen NIB without TRMS with and asking price of $450, and some used with TRMS for $40 without leads or anything else. This one has the HV probe and is calibrated. Sure it might look expensive for an used old meter without many features, but you can use it anywhere outside and inside and it comes with the HV probe which can cost you $60+ on some auctions. I highly recommend that someone here grab this if you are looking for a multimeter for rugged use, HV measurement, or just if you want a really good general multimeter that you can count on.

author: KJDS
author_rank: Super Contributor
timestamp: July 20, 2015, 07:06:55 am
content: If anyone is interested, I've got a big pile of Fluke 25 which I've not got round to testing yet.

author: Shock
author_rank: Super Contributor
timestamp: July 20, 2015, 05:45:07 pm
content: The Fluke 27/FM are really nice meters, I have a box of them now, got them mainly as they have True RMS, good input protection and easy to repair and calibrate. The case is quite large compared to a regular 80 series, many of these have been serviced with the last few years so run like new.

author: edavid
author_rank: Super Contributor
timestamp: July 20, 2015, 05:52:51 pm
content: Wow, that seems overpriced @ $95 + ship. I usually see these kits for around $50. The US military bought zillions of them (AN/PSM-45A), as well as the previous Simpson 467 kits (AN/PSM-45), so they are not at all rare.

author: PaulAm
author_rank: Frequent Contributor
timestamp: July 20, 2015, 05:57:18 pm
content: For the whole kit, $95 isn't bad, but I paid less than that shipped for the one I got. If you don't need frills, it's a pretty decent meter.I wish it had an auto-off, but the battery life is quite good.

author: GreyWoolfe
author_rank: Unknown
timestamp: July 21, 2015, 03:07:14 am
content: I bought mine about a year and a half ago and paid $75 shipped with case, HV probe and a cheap set of standard probes. I put a set of Brymen lead from Frankie and Bob's your Uncle.

author: Lightages
author_rank: Unknown
timestamp: July 21, 2015, 03:08:47 am
content: Yes, Like I said the prices are quite variable. This might not be the best price in history, but it has a full current calibration and the price is not bad. If I did not have one already I would be buying it.

author: saturation
author_rank: Super Contributor
timestamp: July 25, 2015, 04:01:18 pm
content: Great meter, and the price is right considering it comes with case and the HV probes. Just know those are pre-CAT rating meters. Meter alone on eBay runs at a low from $30-50.

author: Shock
author_rank: Super Contributor
timestamp: July 26, 2015, 04:45:57 am
content: A good inside shot.

author: Shock
author_rank: Super Contributor
timestamp: July 26, 2015, 04:51:36 am
content: Quote from: saturation on July 25, 2015, 04:01:18 pmTo expand on that a little..."They are HRC (high rupture capacity) fuses in the 27/FM, which is why they are so big. It just gives it an added level of safety. The 27/FM came out before IEC safety category ratings became the norm, but by current standards the 27/FM is a CAT III 1000 volt, CAT IV 600 volt rated meter. There are 10 safety components within the 27/FM. "http://www.antiqueradios.com/forums/viewtopic.php?f=8&t=167123

author: saturation
author_rank: Super Contributor
timestamp: July 28, 2015, 12:02:59 pm
content: Thanks for that quote and PCB photo.Alas, IEC criteria did not exit before 1992? so its really not possible to make the conclusion I marked in the quote in bold. A common issue for old DMMs are creepage and clearance criteria. Those criteria were widened even more over the next generation IEC criteria.In the final analysis unless there is a true NRTL lab mark on the chassis, marking is part of the safety criteria, the meter isn't safety CAT rated.An eevblog thread also shows the problem as luckily, there are 2 versions of the 27 to make a side by side comparison, and these meters are over 10 years apart in design age.Compare a true CAT III listed version 27 [ yellow case] against the non-CAT 27/FM model [dark grey case]. Even if you don't know the criteria, it demonstrates it.https://www.eevblog.com/forum/testgear/fluke-27-27fm-side-by-side-tear-down/Here are problems I see just on perusing your photo:The 9V battery leads sit right on top of the high-current shunt.The 9V battery leads are close to the rotary switch.The mA wire is too close to the 9V battery leads as well as another trace near the riser board.The 9V battery leads course beside high current fuse tracings and are purposely retained beneath the fuse riser board.The 2 fuses are too close to each other.What can happen? Low probability but serious consequences.If the meter were used measuring high current for extended periods, a hot shunt wire could damage the already thin 9v battery insulation, and could short the battery to the amps input. A kV fault could arc into the isolated power supply via the 9v leads to the DMM.There could be more issues if I could trace the PCB, which I would do if I bought this meter and had to rework it for more safety.In addition, there are some design issues that are not faults, but can be improved.The fuse cover is removable and separate from the battery lid; users should always replace an intact fuse lid in a working meter. Without it, the fuses are exposed to the 9V battery and the battery case can short exposed leads.When I've more time I'll post photos with annotations.Bottom line, is the 27/FM dated 1986 designed meter was ahead of its time in terms of safety, as the input section required few PCB redesigns to make it CAT III rated by the late 1990s as shown in the later model 27, but it still needed changes.Quote from: Shock on July 26, 2015, 04:51:36 am

author: saturation
author_rank: Super Contributor
timestamp: July 28, 2015, 12:49:50 pm
content: Here are close ups on the safety areas of the 27.For marks A,B,C an insulation tube cover the 9V leads. The added material remediates any creepage/clearance issues as well as added protection from heat, in the 80 series this tube in newer DMMs is braided silica.In mark D, the wire is repositioned farther away.In mark E, the conductive lead of the riser board is replaced by an insulated wire.The fuse box of the 'yellow' 27 is dual chamber, isolating the fuses from each other.

author: Shock
author_rank: Super Contributor
timestamp: July 28, 2015, 02:34:32 pm
content: If I recall correctly on the grey 27/FM, the battery is mostly (but not totally) isolated from the fuses as you clip the battery into the holder then insert it and screw it down. The fuses I think are slightly exposed to the PCB still though. The battery wire seems an easy fix and this is the one that stands out to me.That problem with forgetting to put the fuse cover back on (the yellow version?), that is a really bad one.

author: saturation
author_rank: Super Contributor
timestamp: July 28, 2015, 06:31:42 pm
content: Sorry, my error. I saw a video of the door. The 27FM fuses have no compartment, the 27FM battery cover compartment is for the battery and provides a barrier to separate the battery from the fuses; no chance of forgetting to put a fuse cover there. However, there is still a clearance issue for the fuses; one could cover portions of one fuse with electrical tape.