Fluke 79 acting up
 

This thing has performed flawlessly for many years, but when I turned it on
today something was not right. The ohms range flickers random readings, with
no probes plugged in I get around 230K on the display, or 2.22M, depending
on the range, which would imply that the problem is ahead of the scaling
circuit. When I switch to the low ohms range, the reading starts around 240
ohms and then drops to -0.00 over a period of 10 seconds or so, frequency
reading works, but AC volts reads 70mV when plugged into a 120V outlet.
Something strange is going on! I realized that I don't currently have a
backup meter, I suppose I could use this as an excuse to buy a true RMS
Fluke, I don't think I can bring myself to buy a cheapie, except perhaps as
a backup. Anyone run into this?

Fluke 79 acting up
 

"James Sweet" wrote in message
news:Woopj.1074$f73.936@trndny08...
This thing has performed flawlessly for many years, but when I turned it
on today something was not right. The ohms range flickers random readings,
with no probes plugged in I get around 230K on the display, or 2.22M,
depending on the range, which would imply that the problem is ahead of the
scaling circuit. When I switch to the low ohms range, the reading starts
around 240 ohms and then drops to -0.00 over a period of 10 seconds or so,
frequency reading works, but AC volts reads 70mV when plugged into a 120V
outlet. Something strange is going on! I realized that I don't currently
have a backup meter, I suppose I could use this as an excuse to buy a true
RMS Fluke, I don't think I can bring myself to buy a cheapie, except
perhaps as a backup. Anyone run into this?


Sorry, it's a 77, not a 79.

Fluke 79 acting up
 

James Sweet wrote:

"James Sweet" wrote in message
news:Woopj.1074$f73.936@trndny08...

This thing has performed flawlessly for many years, but when I turned it
on today something was not right. The ohms range flickers random readings,
with no probes plugged in I get around 230K on the display, or 2.22M,
depending on the range, which would imply that the problem is ahead of the
scaling circuit. When I switch to the low ohms range, the reading starts
around 240 ohms and then drops to -0.00 over a period of 10 seconds or so,
frequency reading works, but AC volts reads 70mV when plugged into a 120V
outlet. Something strange is going on! I realized that I don't currently
have a backup meter, I suppose I could use this as an excuse to buy a true
RMS Fluke, I don't think I can bring myself to buy a cheapie, except
perhaps as a backup. Anyone run into this?



Sorry, it's a 77, not a 79.


did you check the fuse in it?


--
"I'd rather have a bottle in front of me than a frontal lobotomy"

"Daily Thought:

SOME PEOPLE ARE LIKE SLINKIES. NOT REALLY GOOD FOR ANYTHING BUT
THEY BRING A SMILE TO YOUR FACE WHEN PUSHED DOWN THE STAIRS.
http://webpages.charter.net/jamie_5"

Fluke 79 acting up
 

James Sweet wrote in message
news:Woopj.1074$f73.936@trndny08...
This thing has performed flawlessly for many years, but when I turned it
on
today something was not right. The ohms range flickers random readings,
with
no probes plugged in I get around 230K on the display, or 2.22M, depending
on the range, which would imply that the problem is ahead of the scaling
circuit. When I switch to the low ohms range, the reading starts around
240
ohms and then drops to -0.00 over a period of 10 seconds or so, frequency
reading works, but AC volts reads 70mV when plugged into a 120V outlet.
Something strange is going on! I realized that I don't currently have a
backup meter, I suppose I could use this as an excuse to buy a true RMS
Fluke, I don't think I can bring myself to buy a cheapie, except perhaps
as
a backup. Anyone run into this?




I invested in a moulded rubber surround for my 77, after repairing one
that had been jarred and the main SMD chip had loosened. Someone I know
managed to put his knee on his, while working on the floor, and also
dislodge the main chip. Both repaired after attending to the main chip.


--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/

Fluke 79 acting up
 

This might seem stupid, but have you checked the battery? Is the "lo bat"
annunciator displayed?

Fluke 79 acting up
 

I invested in a moulded rubber surround for my 77, after repairing one
that had been jarred and the main SMD chip had loosened. Someone I know
managed to put his knee on his, while working on the floor, and also
dislodge the main chip. Both repaired after attending to the main chip.



I have the rubber surround, and it hasn't been jarred, it was sitting in the
closet where I always keep it.

I ordered a Fluke 187, I've wanted true RMS for a while anyway. When that
gets here I'll use it to try to fix the 77 and use that as a backup.

Fluke 79 acting up
 

"William Sommerwerck" wrote in message
. ..
This might seem stupid, but have you checked the battery? Is the "lo bat"
annunciator displayed?




It's not displayed, but then I suppose it's worth checking the battery
anyway, I haven't, will do that tonight.

Fluke 79 acting up
 

"James Sweet" wrote in message
news:Ifwpj.2296$eD3.137@trndny05...

"William Sommerwerck" wrote in message
. ..
This might seem stupid, but have you checked the battery? Is the "lo
bat"
annunciator displayed?




It's not displayed, but then I suppose it's worth checking the battery
anyway, I haven't, will do that tonight.



You should check its battery, that's where your problem is. Electronic
meters utilize A/D converter, the converter uses Voltage reference, when
battery is weak it give faulty voltage reference, as a result you get
faulty reading. Do not rely on voltage reading, sufficient voltages do not
mean sufficient Battery without enough current in battery.

Fluke 79 acting up
 

"Jakthehammer" wrote in message
...

"James Sweet" wrote in message
news:Ifwpj.2296$eD3.137@trndny05...

"William Sommerwerck" wrote in message
. ..
This might seem stupid, but have you checked the battery? Is the "lo
bat"
annunciator displayed?




It's not displayed, but then I suppose it's worth checking the battery
anyway, I haven't, will do that tonight.



You should check its battery, that's where your problem is. Electronic
meters utilize A/D converter, the converter uses Voltage reference, when
battery is weak it give faulty voltage reference, as a result you get
faulty reading. Do not rely on voltage reading, sufficient voltages do
not
mean sufficient Battery without enough current in battery.


Sorry if I confuse you, let me try again:

You should check its battery, that's where your problem is. Electronic
meters utilize A/D converter. The A/D converter uses bat as Voltage
reference, when battery is weak it gives faulty reference, as a result you
get faulty reading. Change the battery with fully charge.

Fluke 79 acting up
 

"Jakthehammer" wrote in message
...

You should check its battery, that's where your problem is.
Electronic meters utilize A/D converter. The A/D converter
uses bat as Voltage reference...

Actually, a semiconductor device similar to a Zener diode is used as the
voltage reference. But the battery has to be at or above the device's
threshold to provide a stable reference.

Fluke 79 acting up
 

You should check its battery, that's where your problem is. Electronic
meters utilize A/D converter, the converter uses Voltage reference, when
battery is weak it give faulty voltage reference, as a result you get
faulty reading. Do not rely on voltage reading, sufficient voltages do
not
mean sufficient Battery without enough current in battery.


I put a brand new battery in it, the symptoms are unchanged.

Fluke 79 acting up
 

"Meat Plow" wrote in message
...
On Mon, 04 Feb 2008 04:10:23 +0000, James Sweet wrote:



I invested in a moulded rubber surround for my 77, after repairing one
that had been jarred and the main SMD chip had loosened. Someone I know
managed to put his knee on his, while working on the floor, and also
dislodge the main chip. Both repaired after attending to the main chip.



I have the rubber surround, and it hasn't been jarred, it was sitting in
the
closet where I always keep it.

I ordered a Fluke 187, I've wanted true RMS for a while anyway. When that
gets here I'll use it to try to fix the 77 and use that as a backup.

Do you have a 77 or was the 79 a typo?


The 79 was a typo, I have a 77, and I ordered an 87, I'm full of typos
lately. I really liked the 77, aside from its lack of true RMS, it did
everything I ever asked it to, I hope the 87 lives up to what I've come to
expect.

Fluke 79 acting up
 

James Sweet wrote:
This thing has performed flawlessly for many years, but when I turned it on
today something was not right. The ohms range flickers random readings, with
no probes plugged in I get around 230K on the display, or 2.22M, depending
on the range, which would imply that the problem is ahead of the scaling
circuit. When I switch to the low ohms range, the reading starts around 240
ohms and then drops to -0.00 over a period of 10 seconds or so, frequency
reading works, but AC volts reads 70mV when plugged into a 120V outlet.
Something strange is going on! I realized that I don't currently have a
backup meter, I suppose I could use this as an excuse to buy a true RMS
Fluke, I don't think I can bring myself to buy a cheapie, except perhaps as
a backup. Anyone run into this?

Is the fuse intact?

--
God help us all,
The next President of the United States will be a liberal.

Fluke 79 acting up
 

"clifto" wrote in message
...
James Sweet wrote:
This thing has performed flawlessly for many years, but when I turned it
on
today something was not right. The ohms range flickers random readings,
with
no probes plugged in I get around 230K on the display, or 2.22M,
depending
on the range, which would imply that the problem is ahead of the scaling
circuit. When I switch to the low ohms range, the reading starts around
240
ohms and then drops to -0.00 over a period of 10 seconds or so, frequency
reading works, but AC volts reads 70mV when plugged into a 120V outlet.
Something strange is going on! I realized that I don't currently have a
backup meter, I suppose I could use this as an excuse to buy a true RMS
Fluke, I don't think I can bring myself to buy a cheapie, except perhaps
as
a backup. Anyone run into this?

Is the fuse intact?


I assume so, I didn't do anything that would blow it, but other times the
fuse has blown it has not exhibited any unusual behavior. I know what I'm
doing, I tried all the simple stuff, something has failed.

Fluke 79 acting up
 

I have an old 77. Serial number 4333xxxxxx. Still works like a charm.
Zeros out on any setting. Wouldn't mind having an 87 and keeping the 77
for a backup. Where did you find the best price?


Ebay, they tend to go for about $160 used and in good shape, closer to $300
new. There's several different models of 87, make sure you know which one
you're getting.

Fluke 79 acting up
 

"William Sommerwerck" wrote in message
...
"Jakthehammer" wrote in message
...

You should check its battery, that's where your problem is.
Electronic meters utilize A/D converter. The A/D converter
uses bat as Voltage reference...

Actually, a semiconductor device similar to a Zener diode is used as the
voltage reference. But the battery has to be at or above the device's
threshold to provide a stable reference.



Correctly, the zener (or an IC reference circuit) are part of the A/D
circuit. You cannot design a complete A/D without Voltage Referencing.

Jack....

Fluke 77 acting up
 

James Sweet wrote in message
news:q8Lpj.974$Qj3.511@trndny07...

"clifto" wrote in message
...
James Sweet wrote:
This thing has performed flawlessly for many years, but when I turned
it
on
today something was not right. The ohms range flickers random readings,
with
no probes plugged in I get around 230K on the display, or 2.22M,
depending
on the range, which would imply that the problem is ahead of the
scaling
circuit. When I switch to the low ohms range, the reading starts around
240
ohms and then drops to -0.00 over a period of 10 seconds or so,
frequency
reading works, but AC volts reads 70mV when plugged into a 120V outlet.
Something strange is going on! I realized that I don't currently have a
backup meter, I suppose I could use this as an excuse to buy a true RMS
Fluke, I don't think I can bring myself to buy a cheapie, except
perhaps
as
a backup. Anyone run into this?

Is the fuse intact?


I assume so, I didn't do anything that would blow it, but other times the
fuse has blown it has not exhibited any unusual behavior. I know what I'm
doing, I tried all the simple stuff, something has failed.




If the fuse is blown you get a consistent reading of about 1 per cent of the
true reading.


--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/

Fluke 77 acting up
 

If the fuse is blown you get a consistent reading of about 1 per cent of
the
true reading.



That isn't anything like is going on here. If I set it to read low ohms for
example, it starts out at around 300 ohms, then ticks down steadily until
after a few seconds the continuity beeper activates and then it keeps going
down to -0.00. If I set it to the regular ohms range, the bargraph ticks
rapidly. AC volts reads a few millivolts regardless, haven't tried DC volts
yet.

Fluke 77 acting up
 

I bought a 73 from a pawn shop years ago and it started doing wierd
stuff right away . I found several cold solder joints here & there ..
been working fine ever sence .

My 83 shortly after new started goofing up . It was the rubber thing
that connects the screen . Later it would start making chirping sounds
when turned off . That was a switch on the back of the circuit board .
This meter sits in a desk drawer and seldome gets used , it still looks
like brand new . I thought Fluke was bullet proof .

Fluke 79 acting up
 

I want the 87-V I guess. I won't buy used though. While I got your
attention, do the digits on you 77 appear solid black? Mine look a bit
brownish and I don't remember if they were ever black. I've had it new
since around 1987 if memory serves me correctly.

There are a few authorized Fluke dealers within driving distance from me.
I guess I'll make some calls tomorrow and see what prices I can get. These
places don't sell to joe consumer so they usually have competitive
pricing.


I've only ever bought used, in this case it was a demo or some sort and
comes in the original box with accessories and warranty, I'm not gonna pay
another hundred bucks to get to break the shrinkwrap. I saw a surprising
number of new and nearly new Flukes on ebay, with many going substantially
below retail. For some silly reason, I dislike the new wedge shaped models
and prefer the classic style. I have no logical reason for that though as
it's a tool.

The digits are black on the 77, though some of the segments are a bit washed
out. I fixed that years ago by washing the zebra strips but it came back
eventually.

Fluke 79 acting up
 

James Sweet wrote:

I invested in a moulded rubber surround for my 77, after repairing one
that had been jarred and the main SMD chip had loosened. Someone I know
managed to put his knee on his, while working on the floor, and also
dislodge the main chip. Both repaired after attending to the main chip.




I have the rubber surround, and it hasn't been jarred, it was sitting in the
closet where I always keep it.

I ordered a Fluke 187, I've wanted true RMS for a while anyway. When that
gets here I'll use it to try to fix the 77 and use that as a backup.


187,189 has been discontinued by fluke and replaced with a 287,289..

So beware of people selling you out dated meters.

get a 289, you'll like it! :)


--
"I'd rather have a bottle in front of me than a frontal lobotomy"

"Daily Thought:
Can't think of any, that's why i'm here!"
http://webpages.charter.net/jamie_5"

Fluke 79 acting up
 

187,189 has been discontinued by fluke and replaced with a 287,289..

So beware of people selling you out dated meters.

get a 289, you'll like it! :)




The 77 I'm replacing is over 15 years old, it still served most of my needs
just fine, all it lacked was true RMS. What do I care if a meter is out
dated?

Screw the 289, it'd cost me 3 times what the 87 I found did, and I can't see
anything extra it does that I need. That's a lot of budget I could use for
other hobbies.

Fluke 79 acting up
 

On Feb 3, 2:15*pm, "James Sweet" wrote:
This thing has performed flawlessly for many years, but when I turned it on
today something was not right. The ohms range flickers random readings, with
no probes plugged in I get around 230K on the display, or 2.22M, depending
on the range, which would imply that the problem is ahead of the scaling
circuit. When I switch to the low ohms range, the reading starts around 240
ohms and then drops to -0.00 over a period of 10 seconds or so, frequency
reading works, but AC volts reads 70mV when plugged into a 120V outlet.
Something strange is going on! I realized that I don't currently have a
backup meter, I suppose I could use this as an excuse to buy a true RMS
Fluke, I don't think I can bring myself to buy a cheapie, except perhaps as
a backup. Anyone run into this?

The rotary switches get dirty over time. Take the meter apart and
clean the rotary switch with contact cleaner. If there's carbon
strips on the back side clean them with an alcohol soaked Q tip.
Also, clean the button grids on the circuit board with alcohol.

good luck

Bob
WC3P

Fluke 79 acting up
 

The rotary switches get dirty over time. Take the meter apart and
clean the rotary switch with contact cleaner. If there's carbon
strips on the back side clean them with an alcohol soaked Q tip.
Also, clean the button grids on the circuit board with alcohol.



Tried it, no change. I covered all the easy stuff, including touching up any
suspect solder joints I found.

Fluke 77 acting up
 

James Sweet wrote in message
news:pjaqj.3590$f73.1440@trndny08...
The rotary switches get dirty over time. Take the meter apart and
clean the rotary switch with contact cleaner. If there's carbon
strips on the back side clean them with an alcohol soaked Q tip.
Also, clean the button grids on the circuit board with alcohol.



Tried it, no change. I covered all the easy stuff, including touching up
any
suspect solder joints I found.



Have you tried, as a test, cable tie/s around meter body plus packing piece
plus folding wooden clothes peg wedges, over the main chip ?


--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/

Fluke 77 acting up
 

Meat Plow wrote:
On Wed, 06 Feb 2008 08:05:14 +0000, N Cook wrote:

James Sweet wrote in message
news:pjaqj.3590$f73.1440@trndny08...
The rotary switches get dirty over time. Take the meter apart and
clean the rotary switch with contact cleaner. If there's carbon
strips on the back side clean them with an alcohol soaked Q tip.
Also, clean the button grids on the circuit board with alcohol.


Tried it, no change. I covered all the easy stuff, including touching up
any
suspect solder joints I found.


Have you tried, as a test, cable tie/s around meter body plus packing piece
plus folding wooden clothes peg wedges, over the main chip ?

How about baking it in the oven with Ricotta cheese and a good Italian
sauce?

Now then... don't be sarky ;)

Ron(UK)

Fluke 79 acting up
 

Jakthehammer wrote:

Correctly, the zener (or an IC reference circuit) are part of the A/D
circuit. You cannot design a complete A/D without Voltage Referencing.

Jack....


The reference may also be a separate IC. I've used a lot of them over
the years. Our telemetry receivers used a 10.000 volt reference in
multiple systems, so we used an external reference with a buffer so it
could be trimmed to exactly 10.000 volts.


A low voltage zener isn't suitable for a reference in a meter. The
knee is too soft, and they drift with temperature changes. If all you
want is +/- 10% tolerance it would be ok, but that level was obsolete by
WW-I.


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

Fluke 79 acting up
 

On Feb 4, 7:58 pm, "James Sweet" wrote:
I want the 87-V I guess. I won't buy used though. While I got your
attention, do the digits on you 77 appear solid black? Mine look a bit
brownish and I don't remember if they were ever black. I've had it new
since around 1987 if memory serves me correctly.

There are a few authorized Fluke dealers within driving distance from me.
I guess I'll make some calls tomorrow and see what prices I can get. These
places don't sell to joe consumer so they usually have competitive
pricing.

I've only ever bought used, in this case it was a demo or some sort and
comes in the original box with accessories and warranty, I'm not gonna pay
another hundred bucks to get to break the shrinkwrap. I saw a surprising
number of new and nearly new Flukes on ebay, with many going substantially
below retail. For some silly reason, I dislike the new wedge shaped models
and prefer the classic style. I have no logical reason for that though as
it's a tool.

The digits are black on the 77, though some of the segments are a bit washed
out. I fixed that years ago by washing the zebra strips but it came back
eventually.

I had a similar problem with a 79. Fluke had a problem with the
cleanliness of the LCD Display contacts on some versions. Take apart
the meter & remove the LCD display. On a flat friendly surface,
carefully thoroughly clean the contacts with an eraser. Make sure no
residue is left & re install. Made mine look better than new.