Fluke 77 teardown, calibration and servicing (
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- เผยแพร่เมื่อ 26 เม.ย. 2015
- How to calibrate a Fluke 77 series 1 (77-1) plus a bonus teardown to see what's inside. Tiaan shows how you can service and recalibrate the meter yourself.
Servisol Super 10 contact cleaner:
www.amazon.co.uk/Brand-Serviso...
Additional info on how to remove the Fluke 77 selector knob can be found here:
mrmodemhead.com/blog/fluke-70-...
Equipment used:
Brymen BM867 as a reference meter
Fluke 77 series IV (77-4) as a double-check
5V voltage regulator with resistor divider network
Shot on a Canon 70D and edited in Sony Vegas
Intro from Ratatat: www.ratatatmusic.com
Extro from Blake Robinson: / blaketothefuture - วิทยาศาสตร์และเทคโนโลยี
![[UNCUT] ที่นี่ที่แรก ปู - หาญส์ พูดถึงมหากาพย์หนี้สิ้น I คนดังนั่งเคลียร์ I 10 ก.ค.67](http://i.ytimg.com/vi/KDNA9DZ0p4U/mqdefault.jpg)
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I was issued with one in 1983 when I qualified, I just managed to get one of the net in good condition and will be giving it a similar service, it brings back good memories! dankie Tiaan
I bought a Fluke 73 and a Fluke 77 in 1982. Been working great since then. Very happy.
My parents gave me a Fluke 77 for Christmas 35 years ago. I still have it today and it works great.
A quick search for 'Fluke 77 calibration' - I wasn't too hopeful but this popped up as the first video. Brilliant! Concise, well filmed and factually packed. I couldn't have asked for anything better. I followed the calibration advice and you are right - it is great to see two together reading identical values.
I wouldn't have attempted the calibration without seeing how easy it was, just in case I made it worse.
Not many electronic items around these days, will still be working in 30 years and handling near daily use. Good 'ole Fluke.
Thanks for taking the time to make the video.
A big pleasure, Craig. All the best.
This is so cool, I’ve had my meter for over 20 yrs, it’s time for a good cleaning/ lube as you shown so well in detail.Thank you for your posting.
I have a Fluke 73 that has served me very well for decades. I would like to test its calibratration as well, looks very similar to your 77. Great video Thank you!
I rescued my fathers water damaged 73-III (it looks pretty much identical to the one in this video) last weekend. The inside had been wet for several months after it was being left outside in the rain, but the only damage was some corrosion on the battery connectors. I removed the old solder and applied new. I then cleaned the PCB with 99,9% isopropyl alcohol, lubed the selector switch with silicone grease as well as the screws. I also polished the lens and gave both the case, leads and the cover a good scrub in hot soapy water with a bit of degreaser. It almost looked brand new when re-assembled. I own a 289, 87-V, 179, 73-III and 101.
That's a great story, Robert. The 73, 75 and 77 series meters have a massive 2000 hour battery life. Does it still measure accurately?
@@TechBench Thanks! As far as I can tell it's still accurate. I've only measured 235VAC and a couple of resistors. My main priority was to get it dried out and cleaned as the ohms readings were all over the place even without leads connected. Once the DMM was dried and cleaned, the readings were normal. I'll have to compare the readings to my 289 (calibrated 06/2017) and see how accurate it is. I'll post my findings here.
I bought one of these at a garage sale for $1.00 like 5yrs ago. It worked but the battery you could tell was dying at that time. Just today i got it out and the battery was dead. I was about to throw it in the garbage.. Thankfully i decided to go online and read about them. An then seen what they cost new. lol. The new model 77 retails for $350.00. Thank you for this video!
They are truly great meters and, due to the highly accurate resistor network will maintain their accuracy, literally, for decades.
I can just imagine in 40 years, a youtube video: "I found this 40 year old Chinese multimeter, lets see if we can fix it"
"Oh, the inside has turned to liquid"
Didn't that chinees terminator turn to liquid?
I purchased a 77 in 1981. Fried it by trying to measure too much current. Sent it to Fluke and they repaired for free. Used it daily until 1998 when I changed my career to computers. Still works great today.
Awesome video. Just what Id hoped I would find. Thanks much. Going to get this fluke meter now. Thanks again.
Thanks for watching - I hope you get many hours of joy from your Fluke 77.
Thank you for the video. I found it after I did same work by my model was Fluke 75 series. They look identical.
Thank you my dear friend for this wonderful video.
Perfect!! Now I can refurbish mine 😊
Thank you 👍👍
Anticlock turn..... i see first time in youtube who use this safe method for delicate plastic threads.. Excelent :)
Pretty much every video I've ever seen on electronics repair the person does this, even if they don't say out loud they are doing it. Obviously you should turn opposite to make sure you are engaging with the existing threads. I realized that somewhere between the age of 3 and 6.
Good, thorough video. Thank you!
Thanks! Just changed the LCD in my 73-3 multimeter. Like new!
It's very good... Could you please make a video of calibration and troubleshooting of brymen multimeter
Awesome video.
Thanks!
The bar graph was why i bought my Fluke 77 way back in the '80s but it never convinced me it was as good as moving needle so I never used it. Now my ammeter is out of cal although the volts and ohms are ok.
Thumbs up for how to replace the screws. I have been doing this all my working life and am still amazed that not a lot of technicians have the intuitive intelligence to carry out this simple alignment before screwing it in. Maybe this should be a part of basic training when colleges start a new student intake. Sadly, the old training regime is dying away due to lack of funding and we're producing dumbed down techs.
Exactly, although I'd say teach it from kindergarten! But seriously, I thought it was something people just knew. It's baffling when you come across people who are completely oblivious to this simple, yet vital procedure. I do it without thinking, and I've been doing it since I can remember. SMH, I dunno..
You would lose all faith in humanity if you experienced the amount of people that I have seen cross-thread screws and bolts. From working in automotive shops right out of high school to working at engineering firms on the Fortune 500 list, these dumbasses will do it over and over again without realizing what they are doing wrong. I have witnessed electronic techs that are hired as an intern and electronic techs that have recently graduated do this while I am a college drop out. Somehow these guys are supposedly more qualified than I am to do the same job since they have a piece of paper saying so. I guess?
Basically everyone does this. I don't know anyone who takes apart electronics who doesn't first turn the opposite way to engage the existing threads. It's common sense.
@@garretts228 Bitter much? I've seen plenty of 60 year old morons cross thread bolts and screws. The issue is whether or not the particular person cares or is incentivized to care about what they are screwing in. Anyone repairing their own equipment counter-spins to engage existing threads, it is common sense, not some "enlightened lost knowledge". The real issue is shops yelling at everyone to hurry the hell up constantly.
They want people with college degrees because they are hiring engineers. They aren't hiring technicians. Anyone who works at Walmart can handle a screwdriver, multimeter, and soldering iron.
Contact cleaning - @09:01, spray and clean the exposed wiper surface at 11 o'clock, then rotate more to clean the opposing wiper contact surface.
Great video
I have one, still works
Hi. I have a Chauvin arnoux ca 5220 that is a bit odd. It dont zero when i short the leads in dc. It will measure 0.25v more. Can this be adjusted inside. I se several pots with 10k and so on.
Thank you for the video I have the Fluke 75 but the continuity sounder is very low any suggestion I have had mine a very long time but it works well thanks Bob UK
At 06:23 you can see the back of the board. There are two slightly "enlarged" solder points that press up against the piezo transducer - the buzzer - at the back of the case (the flat circle, next to the shielding). Check the contacts and make sure the piezo element itself is still tightly mounted to the case. It uses the case as a resonance box, so make sure it's still tightly affixed.
I have this meter but i love my fluke 11. Yes i love it. In the 77 meter after opening it to fix lcd problems and add backlight i now dont get buzzer. Must have knocked something out of place.
Interesting! How successful was the backlight mod?
My Fluke 77 is having problems with the switch, it kinds of cracks when I turn it, I'm scared it will break, it was my first professional multi-meter and is still my only professional multi-meter after 20+ years.
Thanks for a great video, I have just aquired a Fluke 23 series 1 which is the identical model but in a yellow case. It works fine but I am needing the rubber holster, any idea where I could get one?
Phew, the only place I would think of is to look on ebay where sellers offer broken meters "for parts". If you look around a bit I'm sure you'd be able to find a holster for it. Happy hunting!
@@TechBench Thanks for the swift reply, I will try that. I have a new Fluke 116 but I really like this old meter and enjoy using it.
I have a Fluke 77 that seems to work fine except for the continuity which rings shorted even without leads attached. Do you have any ideas what could be wrong wit it?
Thanks
you should know that the input detection is some kind of optical light sensor. When using this meter in dark spaces it will beep with an input selection error until you shine a light on the input ports. I figured out that it was an optical sensor on the inputs and not some problem with continuity of the input leads.
Any idea how to get a replacement shunt? I accidentally fried mine after decades and would like to replace it, but cannot find it.
Hi nice and close up footage,
I have a fluke 77 II series as I am not that technical minded and only use my fluke for basic stuff , is there anything i can buy where some thing is already made on the market for me to put my fluke test leads into, where I know its a given 2 v 5v etc and see if my multi meter matches up to it,
Hi - yes, there certainly is. You do not state your country of origin, but start by searching for "Voltage reference module" on Ebay or Amazon. These provide a standardized test voltage for your multimeter.
@@TechBench cheers UK England i think we used to be 240v with 10% - 10% + either way, now i think we are 230v with 10%- 10% + either way I think, due too the power grid easing back on power through out uk,
I have the same original model an my piezo buzzer is erratic - if I compress the case or gently push on the selector switch directly with case opened, I can vary the output from nothing to much louder than when simply held. Putting various side loads on the selector actually produced a sound that had a low frequency harmonic which was loud and much easier to hear than the typical high pitched piezo sound (I'm 67.)
I found the piezo but am completely at a loss to understand how it works because it looks like it does not contact the circuit board. Is there some sort of wireless driving or ???
Thanks
Tom
@Tom: the piezo speaker has a nylon "strap" with two graphite contact points (the little black dots) that make contact with the back of the PCB. Some conservative cleaning with IPA should resolve that issue.
The same IPA can also be used to clean up the contact selector if you do not have any contact cleaner available.
Howdy Tech I have an odd question but i think i might already know its answer but i thought i would ask and see if you come up with something different from me. My Question is how do you calibrate the OHMS with only one adjustment point?
+Im1CrazyCow Ohms measurement is usually taken in a wheatstone bridge configuration, which is situated on the thin-film resistor network. The assumption is that this resistor network remains accurate for the lifetime of the DMM. Thus adjusting the voltage measurement scale also adjusts the voltage measurement on the wheatstone bridge.
There is a good description of how a wheatstone bridge works on Wikipedia:
en.wikipedia.org/wiki/Wheatstone_bridge
Good question, though!
Is that fluke 77 for sale? Lol. My brother gave me his old 75 iii and unfortunately the selector switch rotates all the way around and now the dial won’t stay on. Also when I put it on vac the lcd shows ohms.
Do you know of any stores that can sell the Fluke 87 Multimetter LCD?
I got 77 too but some how didn’t work properly like I turn on vdc just stay - 1.45. Vac on 1.31 unsure what’s go on
i have here a 77 +- 30 years old, still going strong...
It's a solid multimeter. Did you know it has a 2000 hour battery life on a new 9V battery?
Yes, it last forever 3x changed.
at work we have still 5 fluke 77 from 1986 and they are still in spec with out ever calibrating them they only get checked once a year with a calibration standard also from fluke sadly we use now beha amprope meters they are ok but not great
I thought I was the only one doing the anti-clockwise turn well done.
I do this automatically, without thinking. I've done it as far back as I can remember, anything with a thread; nuts, bolts, screws, drink bottles, jars, flashlight tail caps, whatever. It's as natural as breathing to me. It's baffling when people don't know it and then they wonder why they cross-thread everything. I thought it was one of those things people just knew, but you'd be surprised at how many people are unaware.
I also do this as far as I can remember. I guess its all part of the techie gene. Either you have it or you dont :D
Hi i have fluke 77 screen show all number please can u help i clean the screen and the 2 plastic of the screen but still the same problem show all number
Does the Fluke 77 have true RMS? I couldn't find any info on this. Thanks.
This Fluke 77 is an averaging meter. So in other words, it relies on the AC waveform to be a pure sine wave. It's good for measuring mains supply, since that is a sine wave. However, if you measure a 5V (rms) square wave, the meter will display it as 5.5V. Of course, not having a RMS converter chip in it gives it a battery life of 2000 hours! Most modern meters have a battery life of between 100 and 400 hours.
Will the silicone not go down into the contacts over time and coat them making them un-usable
While silicone can be used as an electrical isolator, it is unlikely to work its way into the internals and onto the contact switch. The switches have very good ingress protection. The IEEE actually did a study on this and they determined that silicone vapour deposits also do not affect contact reliability. My own (anecdotal) evidence suggests that it does not cause a problem, since I've been using silicone lubrication on my multimeters for many years.
hi.great vid. i have this same multimeter which i bought off ebay. the ma fuse it came with is a glass fuse and i wanted to change it back to a ceramic fuse. could you please tell me model of original fuse used? many thanks.
+arfan jhangir I had a look at the Fluke 77 series 1 manual and all it states there is that the fuse should be 630mA/250V with 1500A interrupter capacity. So for a ceramic fuse, you'd be looking at something like this:
www.amazon.com/Qty-5X20mm-630mA-Fast-Blow-Ceramic/dp/B004HGFCNI
+TechBench thank you for replying.In your opinion should i use branded fuses or unbranded? is there a difference in quality and is it worth paying extra for branded? many thanks
arfan jhangir
If the price difference is not too great, go for the branded versions. However, as long as it's fast-blow and ceramic I doubt that you can go wrong either way.
Pardon me, but have I missed the calibration part of this video? I just saw you open the meter, clean and grease it but I haven't seen how to calibrate it.
+tulius01 Thanks for asking - look at around 7:24, it's really very quick! :)
My Fluke 75 always reads 3.5 ohms when the probes are shorted, regardless of the range. Is there a 'zeroing' pot somewhere?
My 73 III was giving false Ohm-readings when it had moisture inside.
Great job.
Not sure I would add lube at the outermost diameter of the switch knob. This will attract more dirt.
Enjoyed your 77 tour. Thank you.
+davecc0000
Agreed about the lube on the outside diameter - I wiped it down afterward, so it has that "whisp" of lube on the outside, just to have that idea. Thanks for your kind words.
davecc0000 it may attrack the dirt... but its a good thing if you think that may attrack the dirt from getting inside the meter and fuck the switch mechanism contact and prevent humidity 👍
Any way to "zero" the resistance? No matter how well I re-seat and clean the probes, it never reads below 0.3 ohms.
Unfortunately the Fluke 77 does not have a zero (or delta) function. Only way to handle that is to short out your test leads and then mentally subtract the reading from your final resistor reading.
Do you have a video on how to replace the LCD display? My 77-1 is missing a digit and I would like to make it right.
I don't have a video for the process of replacing the LCD display, however, you might no have to replace it at all. Normally the displays are mounted to the board and uses so-called "zebra strips" to make contact between the glass and the PCB. Taking the strips out and giving them a gentle rub-down with IPA (as well as the contacts on the PCB) will restore connection and likely restore the missing digit. Let us know how it goes!
@@TechBench How about a video on how to get at the strips? This is my first try at opening this meter for anything other than changing the battery. Thanks
I have a problem of "CAL ERR " in fluke 87 series multimeter. Please say the way to solve it.
So, although this video is not related tot he Fluke 87, if any 87-series Fluke displays CAL ERR it could be that the meter has lost its calibration data. You should be able to send it back to Fluke and have it recalibrated under their lifetime warranty guarantee.
por favor destape un multimetro FLUK79 pera ver la posicion del swichs
English por favor?
My fluke 77 keeps flashing OL, I checked the fusable resistor and it's fine, do you have any ideas as to what might be wrong with it?
GhettoRanger I assume this is in Voltage measurement mode, yes? What does it do in the Ohms, Amp and Continuity range?
Thanks for getting back to me so fast. Well, I found a Fluke service manual online and it helped me find the problem it's a loose solder connection on the U2 IC chip on the back of the circuit board, when I press on it the problem goes away. I'm thinking about touching up the solder joints with my soldering iron and some liquid flux. For your future reference it just kept blinking OL with the bar graph on every setting.
GhettoRanger Thanks for the feedback, that is very useful information - hopefully it will help somebody else in the near future :) Agreed on the touch-up idea. Also look for other joints that may be bad that get stressed when you press against the chip - it might not only be the chip leads.
Hi there interesting article. What are the values of the resistors and the cap in the calibration circuit? I'm having problems with the output drifting. Thanks.
The resistor is 1k part and the trimpot is a 2k multi-turn pot (10 turns). The cap is just to quench any oscillation on the 5V regulator, but that specific cap is a 33μF 10V tantalum.
Thanks for the speedy reply. Love the video will service my fluke 70s collection!
the cap is connected to ground?
Yup, to ground and the +9V feed from my bench power supply (in other words on the input to the 5V regulator).
one more question please is one end of the 2k pot to ground?
Very good. TNX. Go Like.
Do you have the part number and where to buy the shunt resistor for the current. Can I use wire and short this out
Hi Kevin, are you talking about the 10A (4-terminal) shunt? Using a wire will likely yield incorrect results, as the wire will not have the specific resistance of the 10A current shunt. Did your shunt get damaged?
@@TechBench yes it burnt up were do I get one
I just picked one of these up for $10.00 today,, Great video not sure I understand the Calibration part though?
The actual calibration is quick, but it does rely on the fact that you have a *known* voltage of 3.000V available. I used a 5V regulator to get the initial 5V and then a simple voltage divider network to tune that down to 3.000V. Of course, I already had a pre-calibrated multimeter available. If you don't have one, you should be able to trust the 77 you have - it's drift really if very small due to the excellent thin-film resistor network it has.
$10 for a Fluke 77? some people have no idea what they are selling.
Much simpler than calibrating an Avo 8!!
Indeed, much simpler. It's a pity that modern multimeters are a lot more difficult to calibrate (but then again, due to the closed-case calibration, they retain their accuracy for a lot longer).
Looks like the 73 3..... Is calibration same for 73 3?
Yes, the calibration procedure is the same for the Fluke 73 series III. Set your input to a known voltage of 3.000V and adjust the R8 pot to match the voltage reading.
I looked at the Servisol Super 10 on Amazon and almost fell out of my chair when I saw the $55 price for one can! I was unable to find the Herschell Silicone Paste here in the US but you can get an 8 oz. can of 3M silicon paste on Amazon for $28.95. Not cheap, but dheaper than paying someone else to work on it.
+Davilo Olivad Whoa ... yeah that's not cheap. I got my Servisol locally for the equivalent of about $12 (US). Look into "Kontakt 60" or "Cramolin Contact cleaner" as an equivalent.The Silicone paste should also be a lot cheaper than you are able to get it for. I'm sure there are a number of equivalents silicon paste/lubricants out there - anything that can lubricate plastic-on-plastic frictional movement.
i know long ago but i often use fermit silicone greas from the hardware store 23 g for 1.50 €
Hi!,
nice video, thanks.
I have an old Fluke 77 like the one showed in your video, the problem with it is that sometimes it wont come out of the selt test.....it just stays with the lcd displaying all segments.
Any ideas?
Thanks again
This could be related to the little finger "legs" of the control chip or the LCD driver chip. On the EEVBlog forums there has been some members that have come across dry joints or loose contacts, causing intermittent faults you describe. If you have the patience, you could reflow those contacts with a fine soldering iron to make sure it is not a contact issue.
Thanks for answering! I'll try that
Dear friends I need to repair hioki 3256-50 digital hitester multimeter
I have the Fluke 75 it must be about 30 years old.....
And I bet it still works like a charm?
Calibration starts at 7:25
it would be useful to show where in the video the calibration info starts
7:45
7:25
where is the calibration part???
Thanks for asking - look at around @, it's really very quick! :)
It looks like your meter is missing a resistor network shield
Hm! Interesting ... I had a quick look at two other teardown videos and both show the shield the same as mine. Do you perhaps have a picture of what the full shield looks like?
@@TechBench Front grey shield that covering resistor network. Not the back silver shield
The Fluke 77 is a fine meter for everyday electronics use - most DC-DC converters have, by their very nature, a DC output, which is fine for measurement with this meter. Some (low quality) AC inverters do not output a pure sine-wave, so I agree that readings with any non-true RMS multimeter will always be out by a few percent.
Fluke 77 still look good !
selector switch tension already gone.
- Nope, it's still in excellent condition and very springy, even after 25 years.
Nice :) i wrong.
Because of its quality. This Fluke 77 is "Made in USA"
Black cover better then 175.
You are a South African who usually speaks Afrikaans at home. Am I right?
Yup.
Teflon better then silicon paist.
using grease in the screw hole will help loosing the screw with the time by itself... i dont know why you do that... sorry but its totally wrong.....
Maybe. But here we are in 2019, almost four years later and the screws are still tight with the meter in almost daily use.
well... its a bit weird haha youre the first guy i saw putting grease in something that need to be tight loll
Teflon better then silicon paist.
- Teflon paste? In my experience, teflon paste oxidizes after a year or two and leaves little "crumbs" in the switch workings. I still prefer Silicon paste.
Thanks the Comment, TechBench. my misstake, i was mean Teflon grease. in my case, silicon paste(grease) hardened after 2~3 years. for Plastic material, i think Two all good choice !