Fluke 15B mods - Page 1
Forum section: electronics / testgear

author: Jasper
author_rank: Contributor
timestamp: February 11, 2014, 07:18:18 pm
content: I couldn't really find any ongoing threads about the 15B/17B Flukes, it's all way old, so I figured new one, what the heck.I got my new 15B the other day. While taking it apart, I noticed that despite external appearances, most of the 17B's functionality appeared to actually be present:{images changed over to final result, full story a few posts down}Both rel and hz/% buttons are there on the PCB and on the rubber keypad, and they even appear to work (I didn't actually check with any signals, but, well, no reason to believe they wouldn't). The only thing not actually physically present is the holes in the top case for the buttons to poke through, and the top bits of rubber have been removed (with a sharp knife, as I've seen a lot in remote controls). Also missing in action is the extra circuitry to measure temperature.Has anyone modified the 15B with holes in the top case and replacement button-analogies to get the Delta/rel function and the frequency function? They seem like they might be useful.And, yes, I'd be drilling a hole through the top case, technically through the blast shielding, but given the location and the fact that the rubber (which actually has a nice lip that is probably part of the blast shielding) is still there, I suspect that will not be too much of an issue. Comments welcomed.

author: retiredcaps
author_rank: Super Contributor
timestamp: February 11, 2014, 10:32:19 pm
content: Quote from: Jasper on February 11, 2014, 07:18:18 pmA Russian website shows a 15B modified into a 17B (almost 4 years ago).http://translate.google.com/translate?hl=en&sl=ru&u=http://techno-mind.ru/instrument/prevrashhenie-fluke-15b-v-fluke-17b-i-obzor-onogo.htmlExcavatoree modified his Fluke 10 into a 12.https://www.eevblog.com/forum/chat/fluke-25-my-first-digital-multimeter/msg36115/#msg36115

author: SoundTech-LG
author_rank: Frequent Contributor
timestamp: February 12, 2014, 12:11:05 am
content: Although many meters may have similar hardware, there also may be a simple change of firmware version loaded in the uProcessor as well, and possibly a different LCD screen with appropriate symbols changed.I think the 79 series II, and the automotive 78 might certainly be a good example of that.

author: Excavatoree
author_rank: Frequent Contributor
timestamp: February 12, 2014, 12:38:29 am
content: Quote from: SoundTech-LG on February 12, 2014, 12:11:05 amThat does happen, but with Fluke, often the firmware will support the functions. As Retiredcaps said, the model 10 supports the capacitance measuring function as well as the max/min function of the model 12.Very strangely, the firmware for the 10 and 12 is different - the 10 lacks the feature that will allow the meter to measure voltage in the ohms mode once the voltage gets above around 4 volts. (sorry, I can't remember it exactly) So, we have the strange case where the 10 firmware is different, but both share the "features without buttons" on the 10.The only way to know for sure is to test.Some of the old 70 series lacked the range change button (in the center of the function knob) but the knob can be repalced and the function will work if a jumper is installed. (Fluke uses a "zero ohm resistor" that is omitted)

author: Jasper
author_rank: Contributor
timestamp: February 12, 2014, 10:26:33 am
content: Quote from: retiredcaps on February 11, 2014, 10:32:19 pmOh, nice. And if you get the non-translated version the pictures still exist as well. (I did notice a (c) 2005 on the board, these meters have been around a bit longer than I thought they had)He's also extended the range switch to get Temp, but that is of course useless -- the board is visibly on the photos lacking the U4/5/6 chips and glue logic that actually provides the temperature measurement according to the schematic, just like on mine. Firmware is just measuring an empty pin in that case.Still, though, especially on a non-datalogging meter, temperature measurement, enh. The other two functions would have been more likely to sway me toward the 17B.QuoteI'm glad to see I'm not the first taking this path, at leastQuote from: SoundTech-LG on February 12, 2014, 12:11:05 amThat's why the photos -- they show the microprocessor responding to both of those buttons with appropriate symbols on the display.

author: Jasper
author_rank: Contributor
timestamp: February 13, 2014, 02:18:00 pm
content: Okay, so I've completed the mod. My 15B is now more like a 16B -- somewhere in between the 15B and 17B.No temperature measurement -- just the ICs required on the PCB (two precision opamps and a temp sensor for the cold side) would cost 6 euros on digikey, not to mention the passives and the two trimpots to be set manually and aaaargh. Not worth it. But I do have Rel and Hz/% modes.Full photoset here:https://plus.google.com/u/0/photos/+JasperJanssen/albums/5979882059447436289I drilled a couple of 8mm holes using a standard spiral wood bit, right in the center of where the buttons would have been. I used the slow speed, and they came out pretty nice. Not terribly user friendly though, poking something through a hole to press the button beneath. I whipped up a quick plastic button in Sketchup and printed a few copies out (you want multiples because otherwise the layers don't cool quickly enough on objects this small). Turned out I'd underestimated the room for the rectangular bit that holds them in place (very rattly), and overestimated how tall they needed to be, so I increased one by a mm and decreased the other by another mm, and tried again. Result is just fine.I love 3D printing.