Fluke 77-IV

[pfrcom]

Considering buying one described as used, mint condition

Any tips on pitfalls, what to look for, what to try out before handing over money

Or is there anything else new I should consider instead ?

[stj]

Re: Fluke 77-IV

build quality isnt what it used to be on fluke stuff,
they are known for failing display panels and the rotary switch is a weak point on most meters as they get older.

i'd recommend just getting this:
http://www.dx.com/p/ut61e-2-6-lcd-di...battery-113306

[retiredcaps]

Re: Fluke 77-IV

build quality isnt what it used to be on fluke stuff,
they are known for failing display panels and the rotary switch is a weak point on most meters as they get older.

The original, and nearly 25 year old, Fluke 80 series 1 can suffer from failing display elastomers.

http://mrmodemhead.com/blog/fluke-8x-faded-lcd/

The original, and nearly 30 year old, Fluke 70 series can have soft/mushy rotary switch.

http://mrmodemhead.com/blog/fluke-70...-knob-removal/

The newest generation, the 77 IV, suffers from neither weak display or poor rotary switch. Depending on the price for the used meter, it can represent a good deal. I got my 77IV for $35 USD.

[retiredcaps]

Re: Fluke 77-IV

http://www.dx.com/p/ut61e-2-6-lcd-di...battery-113306

In another thread, pfrcom, expressed reluctance to measure mains filter capacitor due to high voltage.

https://www.badcaps.net/forum/showthread.php?t=40516

With the UT61E, there are lots of teardown pictures on eevblog which show it has no input protection. Thus, many recommend not using the UT61E for high energy measurements.

The Fluke 77 IV has input protection, as shown teardown pictures.

[retiredcaps]

Re: Fluke 77-IV

Another 77IV here on badcaps.net

https://www.badcaps.net/forum/showthread.php?t=24239

[retiredcaps]

Re: Fluke 77-IV

Any tips on pitfalls, what to look for, what to try out before handing over money

If the seller lets you, open the 77IV and check to make sure the fuses are HRC fuses and not a drill/screw bit or some generic glass fuse.

I bought a Fluke 87 and when I got home, this was my fuse.

https://www.badcaps.net/forum/showpo...2&postcount=17

Also, test the backlight, continuity buzzer to make sure they are working. Maybe bring your existing 77 and do a few comparison measurements with a battery and resistor?

[stj]

Re: Fluke 77-IV

the original 77 is almost as old as i am,
he didnt say it was a mk4 so i assume it's pretty old.
he didnt say the price either.

as for input protection, if your not probing close to 1kv you dont need protection, and if you are - you need better leads than the UNI-T OR the Fluke come with!

i have no concerns metering 400v ish with a cheap meter if the probes are rated atleast 600v and double-insulated.

[pfrcom]

Re: Fluke 77-IV

Thanks for the feedback stj & retiredcaps

I've just been burnt by a fraudulent seller on Gumtree, and this Fluke 77-IV is on both eBay & Gumtree, with the seller wanting me to buy outside eBay, so I'm very wary

Given I'm an amateur, and cautious with electricity, a new UT61E at around half the price of the 77-IV does seem like a more sensible option

@retiredcaps I did buy a set of the hands-free leads you recommended - trying to work up sufficient enthusiasm to have another go at that MPT-301

[Agent24]

Re: Fluke 77-IV

I did buy a set of the hands-free leads you recommended - trying to work up sufficient enthusiasm to have another go at that MPT-301

If you have clip leads then checking primaries is easy. Just hook them up, stand back, and you're good to switch it on. No need to worry about having steady hands or anything. On PSUs where the capacitors stand up, it's probably easier to clip to the rectifier output leads though.

After the first time, you'll likely wonder what you were worried about.
(Like I did after the first time I discharged a CRT - the noise was actually nothing scary compared to the fear I had invented in my own head!)


Sure, it is dangerous to work on powered mains equipment... no doubt about it - but then so is using a chainsaw or driving a car.

Like anything dangerous: Take your time and be careful. Double-check your connections and make sure your multimeter is on the correct range. If you are unsure about something - ASK FIRST.

[stj]

Re: Fluke 77-IV

a new UT61E at around half the price of the 77-IV does seem like a more sensible option

so your being offered a USED fluke for about $120 ???
that sounds like a hell of a lot of money for anything less than an Agilent!!

[retiredcaps]

Re: Fluke 77-IV

Given I'm an amateur, and cautious with electricity, a new UT61E at around half the price of the 77-IV does seem like a more sensible option

@retiredcaps I did buy a set of the hands-free leads you recommended - trying to work up sufficient enthusiasm to have another go at that MPT-301

I would use a 30 year old Fluke 77 that has input protection (as documented in their service manual where you can clearly read and see the input protection) when measuring high voltage with hands free clips.

Input protection on the volts/ohms jack protects the meter and the user in case of an oops moment.

Here is an example. In your country, a large filter capacitor could be charged up to 400V DC if PFC is involved. If you incorrectly leave or set your multimeter on the ohms range and try to measure the DCV across the mains filter capacitor, the 77 will be unharmed.

Other meters that don't have input protection will give varying results.

Here is a video from Dave Jones at eevblog talking about input protection.

http://www.eevblog.com/2012/10/19/ee...tion-tutorial/

Note the Fluke 27 and 77 share similar input protection mechanisms and components.

[retiredcaps]

Re: Fluke 77-IV

I've just been burnt by a fraudulent seller on Gumtree, and this Fluke 77-IV is on both eBay & Gumtree, with the seller wanting me to buy outside eBay, so I'm very wary

Buying from either have their pros and cons. If your instincts tell you something is wrong, listen to them.

Looking at both listings, I personally have no problems buying on Gumtree and trying to get a better price in person. The seller does have make offer as an option on their ebay listing.

In addition, they show the serial number and you can always contact your local police to see if it is stolen?

Given I'm an amateur, and cautious with electricity, a new UT61E at around half the price of the 77-IV does seem like a more sensible option

There is no doubt that Fluke is premium priced compared to most competitors. You have to decide what you will be using the tool for and if it is appropriate.

If you use the existing Fluke 77 for high voltage and the UT61E for low voltage, then that might be a good solution for you.

Note: I don't own a UT61E, but I do own a 77 and 77IV (among others).

[retiredcaps]

Re: Fluke 77-IV

If you have clip leads then checking primaries is easy. Just hook them up, stand back, and you're good to switch it on.

I recently took apart an "used, but working" Motorola DCT3416 (write up coming later sometime), where it obviously had 13 bad capacitors. 3 were on the power board and 10 were on the main/logic board.

I left it unplugged for nearly 4.5 weeks while waiting to get a special security screwdriver to remove the outershell screws.

After I took out the power board and before desoldering the 3 bad caps on the power board, I measured the DCV across the main filter capacitor. My multimeter reported 166.67VDC.

In other words, the main filter capacitor did NOT lose its charge after 4.5 weeks of being unplugged from an AC wall socket.

Here is where things can go wrong. Imagine not knowing that the filter capacitor/components was fully charged to 166VDC (or 400VDC with PFC), a 350C soldering station and working alone.

Sure, it is dangerous to work on powered mains equipment... no doubt about it - but then so is using a chainsaw or driving a car.

That is why I take the more cautious route. Because I can't see electricity, I have a healthy respect for it.

With more education, safe procedures and the right tools, you can work relatively safely and minimize the chances of injury and something going wrong with respect to electricity, chainsaws and driving.

end:

[stj]

Re: Fluke 77-IV

filter caps should always be metered before touching them,
i'v also had stuff in for repair that showed chaged filter caps after days - maybe even weeks since the customer unplugged it.

it's bad design not to put a 2.2meg or 4.7meg resistor across filter caps, but these days shaving off a fraction of a penny on the production line is unfortunatly very common.

i'm also carefull about output caps if there is no load resistor as i'v had the end of my soldering iron damaged a couple of times by bulk-discharge.

[pfrcom]

Re: Fluke 77-IV

so your being offered a USED fluke for about $120 ???
that sounds like a hell of a lot of money for anything less than an Agilent!!

Correct, $120

However, having just received eBay email saying it sold for original asking price of $150, purchase is now a moot point

As retiredcaps has observed, a UT61E in conjunction with my original Fluke 77 will be a good combination

FWIW, I am talking AUD not USD

[stj]

Re: Fluke 77-IV

i gathered that you meant AUD from your profile,
and got the figure by using the dropdown at the top-left of DX webpage to change currency.

[pfrcom]

Re: Fluke 77-IV

Got my UT-61E, and very impressed with it

Doesn't have quite the same feeling of solidity as my original Fluke 77, but maybe current Flukes don't measure up either

Thanks for the recommendation STJ - didn't buy from DX though, too concerned about a counterfeit

From here instead http://www.ebay.com.au/usr/globalsup...84.m1497.l2754 - good buying experience

First cab off the rank was measuring capacitance of primaries from my MPT-301 here https://www.badcaps.net/forum/showthread.php?t=40516 - FWIW, well within spec, also their ESR by Dick Smith meter

[mockingbird]

Re: Fluke 77-IV

build quality isnt what it used to be on fluke stuff,
they are known for failing display panels and the rotary switch is a weak point on most meters as they get older.

i'd recommend just getting this:
http://www.dx.com/p/ut61e-2-6-lcd-di...battery-113306

I read on EEVBlog that Uni-T does not meet their published CAT ratings... So they shouldn't be used for high voltage applications.

There are only a handful of types of ICs in the various high-end DMMs. There's Flukes custom IC, Tektronix' custom IC, and then the same Taiwanese chip used in all the high-end Chinese DMMs.

[Agent24]

Re: Fluke 77-IV

the same Taiwanese chip used in all the high-end Chinese DMMs.

A re-branded ICL7107?

[mockingbird]

Re: Fluke 77-IV

Nah, that's not the IC that does all the mathematics in DMMs...

I think the name of the manufacturer was Cyrustek, but don't quote me on that.