Author Topic: Fluke 289 not quite sorted.  (Read 28228 times)

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Offline nixxon

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Re: Fluke 289 not quite sorted.
« Reply #100 on: October 15, 2018, 05:02:34 pm »
Commongrounder: I really dont know how the «current terminal sensing» works. There are two components (Q24 and Q27) «looking» at each other across both terminal cavities. I would, with my limited electronix knowledge, assume that one side was active and the other was passive. However, both Q24 and Q27 are active components. I even dont know if the terminal sensing discriminates between the two current terminals. I will have to check it out when I get home tomorrow. For all that I know, the DS2 component may register an inserted probe jack and is able to discriminate between the two current terminals throug differently coded signals missing from either Q24 or Q27 when a jack is inserted.

If someone more experienced could share his or her thoughts about how the optical current terminal sensing works in the Fluke 287/289, I would surely be happy to read about it...
 

Offline commongrounder

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Re: Fluke 289 not quite sorted.
« Reply #101 on: October 15, 2018, 05:42:25 pm »
So, I own a 289, and took a peek through the current jacks (not inclined to disassemble it at this time as I’m using it today). I can see a clear plastic prism reflector between the current jacks that appears to be part of the molded plastic jack frame. The light isn’t visible, but I have a small infrared probe which detected IR light in the jack cavities. I believe the diode is an IR LED, and the two outer devices are IR photo transistors. I was able to prove this, as well as understand the reasoning, by trying different combinations of plug insertions. The beeps are in conjunction with an on-screen warning of improper lead positioning. 1) Warning when lead(s) are inserted in current jack(s) in any mode but current measurement modes. 2) Warning when lead is not inserted into one or the other current jack in current measurement modes only. 3) Warning when plugs are inserted into *both* current jacks at the same time, in current measurement modes. Obviously, 3) is not a proper lead configuration for any purpose. This can only be discerned with two independent optical sensors.
Hope you can get the display up and running again. Best of luck.
 
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Offline nixxon

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Re: Fluke 289 not quite sorted.
« Reply #102 on: October 15, 2018, 05:59:21 pm »
Aha, so the tiny guy in the middle (DS2) is the active part and the powered Q24 and Q27 are the sensors? Wow, My mind was set the other way around. The «optical» part of DS2 looks so small. But the transparent top edges of DS2 are angled 45 degrees both left and right and would transmit both ways towards both Q24 and Q27, across both cavities.
[EDIT: Actually there is a transparent optical path between the two A - mA/uA input jacks. The top surface of the DS2 touches the middle of the optical path surface.]
« Last Edit: April 01, 2019, 06:38:08 pm by nixxon »
 

Offline ElecSeb

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Re: Fluke 289 not quite sorted.
« Reply #103 on: October 16, 2018, 05:16:11 am »
Q24 & Q27 = SFH 325 FA-3/4-Z - SIDELED® Silicon NPN Phototransistor in SMT SIDELED®-Package
DS01 = SMD LED (exact type unknown atm)
 
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Offline nixxon

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Re: Fluke 289 not quite sorted.
« Reply #104 on: October 16, 2018, 02:35:29 pm »
(...)
In addition, which I didn’t mentioned this at the beginning, there was a bit of greenish dried fluid marks in on PCB close to Amper input (between the two left input jacks) and similar thing on the top corner of the LCD, close to the soldered wires. I’ve clean it but found no source.
(...)

Very interesting information about the LCD top corner... I will check it out next...
 

Offline nixxon

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Re: Fluke 289 not quite sorted.
« Reply #105 on: October 17, 2018, 04:06:25 pm »
After turning the dial into resistance mode, the display shows 25 M Ohms while probes are open circuit.

When the probes are separated again, the display doesn't return to 25 M Ohms, but shows ~3.7 M Ohms (while probes are open circuit)
The non display of 0L might indicate that one or more of your input protection circuits has been damaged.

You can measure all in circuit and see if they are good.  If not, desolder them to verify.

A MOV should measure infinite resistance.  The PTC should be around 1.1k ohm.  The fusible resistor should be around 1k ohm.

I will have to figure out a way to identify the components that are involved in measuring resistance. I guess watching some of David L. Jones' old DMM teardown videos will be helpful.

In the meantime I used another DMM to measure the voltage output of the 289 terminals (COM and V) while the 289 was in resistance mode. Initially (while displaying 25 M Ohms) the voltage is 1.92 volts. After the terminals have been shorted momentarily the voltage increases to 2.76 volts (while displaying 3.7 M Ohms).

Does anyone have any idea what is going on, and why the voltage increase after the probes have been shorted?

I measured the blue Metal Oxide Varistors (MOV) and they did not show infinite resistance:
RV1: 17.5 M Ohm
RV2: 24.0 M Ohm (not stable)
RV3: 23.5 M Ohm (not stable)

Can they all be bad? I have read that "When MOVs degrade they become more conductive after they have been stressed by either continuous current or surge current." Source: https://iaeimagazine.org/magazine/2004/03/16/metal-oxide-varistor-degradation/

The black Positive Temperature Coefficient (PTC) thermistors were measured ok:
RT1: 1.1 k Ohm
RT2: 1.2 k Ohm


The fusible resistor R4 has a good resistance of 1.01 k Ohm

I also measured the main fuses
XAF1 ("DMM 44/100"): 0.8 Ohm
XAF2 ("DMM-11A"): 0.1 Ohm.

Is XAF1 supposed to have such a high resistance? It seems wrong.

Now I will read the Service Manual for Fluke 76 Chapter 2 Theory of operation and hopefully learn quite a few things about how this and other DMM's work...
I found it here: http://assets.fluke.com/manuals/76______smeng0000.pdf
« Last Edit: October 17, 2018, 07:41:56 pm by nixxon »
 

Offline retiredcaps

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Re: Fluke 289 not quite sorted.
« Reply #106 on: October 17, 2018, 10:34:21 pm »
I measured the blue Metal Oxide Varistors (MOV) and they did not show infinite resistance:
RV1: 17.5 M Ohm
RV2: 24.0 M Ohm (not stable)
RV3: 23.5 M Ohm (not stable)

Can they all be bad?

Desolder all the MOVs and re-measure them out of circuit.  With the MOVs removed, see if the meter works on resistance mode.

Verify that ACV and DCV works with the MOVs on low energy circuits (i.e. no mains, etc).

Quote
I also measured the main fuses
XAF1 ("DMM 44/100"): 0.8 Ohm
XAF2 ("DMM-11A"): 0.1 Ohm.

Is XAF1 supposed to have such a high resistance? It seems wrong.
The fuses only affect current measurement.
 
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Offline retiredcaps

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Re: Fluke 289 not quite sorted.
« Reply #107 on: October 17, 2018, 10:37:03 pm »
In the meantime I used another DMM to measure the voltage output of the 289 terminals (COM and V) while the 289 was in resistance mode. Initially (while displaying 25 M Ohms) the voltage is 1.92 volts. After the terminals have been shorted momentarily the voltage increases to 2.76 volts (while displaying 3.7 M Ohms).
When the non working 289 is set to DCV, its input impedance should be around 11.11M ohm.
 

Offline nixxon

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Re: Fluke 289 not quite sorted.
« Reply #108 on: October 20, 2018, 12:35:30 pm »
In the meantime I used another DMM to measure the voltage output of the 289 terminals (COM and V) while the 289 was in resistance mode. Initially (while displaying 25 M Ohms) the voltage is 1.92 volts. After the terminals have been shorted momentarily the voltage increases to 2.76 volts (while displaying 3.7 M Ohms).
When the non working 289 is set to DCV, its input impedance should be around 11.11M ohm.

When the non working 289 is set to DCV, its input impedance is shown alternating between 11.004 or 11.005 M Ohm on my good 287 and alternating between 11.00 and 11.01 M Ohms on my good 83V. So the impedance of the non working 289 is ~0.105 M Ohm or ~105 k Ohm lower than what you suggested.

A comparison:
When my good 287 is set to DCV, its input impedance is shown as (10.982 M Ohm on the non working 289 and) alternating between 10.99 and 11.00 M Ohm on my good 83V. (and steady 11.00 M Ohm on my 87 (version 1)).

After shorting the probes on the non working 289 for a moment (open probes display 3.7 M Ohm), the reading on the 289 is lowered from 10.982 to 3.6542 M Ohms while the DUT 287 shows 2.7498 VDC. Lots of figures. Go figure...

Are you shure the imput impedance of a 287/289 in VDC mode is supposed to be 11.11 M Ohms?  (rather than 11.00 M Ohms)

The input impedance of my 83V and 87 (version1) in VDC mode are both ~11.11 M Ohms, though.
« Last Edit: October 20, 2018, 12:50:36 pm by nixxon »
 

Offline nixxon

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Re: Fluke 289 not quite sorted.
« Reply #109 on: October 20, 2018, 04:09:14 pm »
The faulty 289 (while in resistance measurement mode) goes from 25 M Ohms open circuit to 3.7 M Ohm open circuit after a resistance below 3.7 M Omhs is registered. Check enclosed log graph where you se me touching both the probes firmer and firmer until measured resistance goes below 3.7 M Ohm.
« Last Edit: October 20, 2018, 04:11:50 pm by nixxon »
 

Offline nixxon

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Re: Fluke 289 not quite sorted.
« Reply #110 on: October 20, 2018, 08:51:16 pm »
In order to troubleshoot the 289 LCD that is not working, I am thinking about using my fully working 287's parts for troubleshooting.

I want to figure out if the LCD of the non working 289 is all right.

What is the best way to go:

1) Connecting the working 287's LCD to the non working 289 multimeter? or
2) Connecting the non working 289's LCD display to the working 287 multimeter?
« Last Edit: October 20, 2018, 09:03:10 pm by nixxon »
 

Offline ElecSeb

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Re: Fluke 289 not quite sorted.
« Reply #111 on: October 21, 2018, 07:12:07 am »
Expected non-working LCD to Working DMM.
This way when it works you know for sure the LCD works.

Other way around when good LCD attached to defect DMM, you know screen from new unit is good, but if it does not work, you know the Mainboard of the defect DMM is broken. But till that moment you still do not know if the suspected LCD is broken.

My 2 cents
 
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Offline nixxon

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Re: Fluke 289 not quite sorted.
« Reply #112 on: October 21, 2018, 02:08:15 pm »
Expected non-working LCD to Working DMM.
This way when it works you know for sure the LCD works.

Other way around when good LCD attached to defect DMM, you know screen from new unit is good, but if it does not work, you know the Mainboard of the defect DMM is broken. But till that moment you still do not know if the suspected LCD is broken.

My 2 cents

I did as you suggested. The LCD from the 289 woke up fine when connected to my good DMM (287).

It seems that the LCD driver circuit on the 289 is no good. I noticed that one of the crystals had a low amplitude (200 mVpp) the way I measured it. According to the Fluke 27 Service Manual a similar 32.768 kHz crystal should measure 600 mVpp or more.:

  • 4. Connect either an oscilloscope or frequency counter, using a low-capacitance probe,
    to pin 54 of U1 or to the junction of C17 and Y1 (the crystal). A 32.768 kHz sine
    wave with an amplitude of approximately 600 mV peak-to-peak should be present at
    the junction of C17 and Y1 (3 V peak-to-peak at U1 pin 54). Note that U2 and the
    display will not operate if the clock signal is not present. If the clock signal is not
    present, the most likely causes are U1, Y1 or C17.

Can a missing (or low) clock signal be a part of the LCD problem when the rest of the meter seems to be working ok?
 

Offline ElecSeb

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Re: Fluke 289 not quite sorted.
« Reply #113 on: October 21, 2018, 04:37:11 pm »
At this moment I do not have a scope available (bought a new one recently and is still in transit).
However did you measure your power lines?

And how do you know that the unit powers-on (sorry if I missed it in your posts).
 

Offline nixxon

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Re: Fluke 289 not quite sorted.
« Reply #114 on: October 21, 2018, 06:09:00 pm »
At this moment I do not have a scope available (bought a new one recently and is still in transit).
However did you measure your power lines?

And how do you know that the unit powers-on (sorry if I missed it in your posts).

Hello. Good luck with your new scope. Are you planning to use it to do measurements on a working 287/289?

I have not measured power lines. I  bought the 289 as non working.

I have fixed one fault in the current terminal sensing and updated the firmware from v1.10 to v1.16.

I can read the 289's "screen" via the IR189USB interface on my computer using FlukeView Forms.

Now I am trying to fix it's LCD driving circuit (LCD itself is working) and the resistance measurement function not reaching "OL" while probes are open circuit.
« Last Edit: October 21, 2018, 06:41:43 pm by nixxon »
 

Offline ElecSeb

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Re: Fluke 289 not quite sorted.
« Reply #115 on: October 22, 2018, 04:27:20 am »
This means the green light from the power button is "ON"?
And concerning SCOPE -> I will measure, but I do not have a working unit.
 

Offline Samogon

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Re: Fluke 289 not quite sorted.
« Reply #116 on: October 22, 2018, 07:57:40 am »
OL on open corcuit is ok.
 

Offline nixxon

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Re: Fluke 289 not quite sorted.
« Reply #117 on: October 22, 2018, 09:02:25 am »
OL on open corcuit is ok.

The meter never displays "OL" in resistance measuring mode. After selecting resistance mode on the rotary switch the DMM displays 25 Mohms initially wile open circuit. If I measure anything with a resistance lower than 3.7 Mohm, the open circuit resistance is displayed as ~3.7 Mohm.

The DMM is latched to ~3.7 Mohm max. (while open circuit) until the rotary switch is rotated to some other mode and then back to resistance mode. Then the DMM indicates 25 Mohm again open circuit.

ElecSeb: Yes, the power button shows a green light for a few seconds while the DMM is booting. Just like a fully functional 287/289.
« Last Edit: October 22, 2018, 10:28:28 am by nixxon »
 

Offline nixxon

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Re: Fluke 289 not quite sorted.
« Reply #118 on: October 22, 2018, 10:25:29 pm »
Today I was troubleshooting the Y1 crystal with the low amplitude signal, still 200mVpp. The input position sensors were however acting up again, beeping all the time. I managed to silence the beeps if I put a piece of paper or a piece of tape along the optical path. It is almost like the transmitter in the middle was transmitting at a wrong angle and that the piece of paper reflected the IR light back onto the receivers.
[EDIT: This makes sense because when the top cover is separated fromt the PCB, the optical path from DS2 to both Q24 (A jack sensor) and Q27 (mA/uA sensor) is removed]


The Y1 frequency was all over the place, varying between 32.667 and 32.720 kHz (using short gate time on the frequency counter due to significant frequency variations)
The Y2 crystal was pretty steady and varied only between 32.7660 and 32.7661 kHz (longer gate time  possible with the stable frequency).

The green light is not lighting up any more during booting, and there is no relay clicking during the boot. (Normally there is a relay click as the green light turns on, and another click as the green light turns off)
[EDIT: It seems that the green diode has failed as it measures 1.9 ohms both ways.]

In other words, there were quite a few setbacks today.   :(
« Last Edit: February 19, 2019, 08:43:45 pm by nixxon »
 

Offline ElecSeb

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Re: Fluke 289 not quite sorted.
« Reply #119 on: October 23, 2018, 08:24:52 am »
Well, start with "off-state" and measure all V on the defined testpoint +-33 TP.

My fluke 289 is turning the greenled on for a short moment, then turns-off, but no screen.
Also no power from the torex PWM IC.
But unfortunately I do not have a lot of time during the day to test mine. I will try this afternoon.

I have created a XLS with all TP and reference values found in this thread (ON & OFF).
Furthermore I have created a second tab with all components I have identified so far. On mine I have tested all SOT32 elements (which are all OK).
I need to add this test data to this XLS before upload.
And last I have added a link to the specific component (I do not guarantee it is 100% correct, but I think it will come close, but any addition later on will be great!).

Only thing I am missing at the moment is a comprehensive TP layout. IN earlier posts some mention TP which are unknown to me (cannot find them visueally and in Calibration manual they are also not mentioned).

Hope to add this info to this topic soon.
 

Offline ElecSeb

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Re: Fluke 289 not quite sorted.
« Reply #120 on: October 23, 2018, 04:49:10 pm »
Update from my side:
This afternoon I have finished my analysis from all SOT23 elements. All seem to be fine.
However last time I was playing with it I massively f&ckedup and created a shortage on U20. This now results in having a short between L1 and ground  |O
Initially the unit did not work and I broke L1 coil, burned 2 capacitors and removed the super-cap. Also removed burned C27 and C36 (hot air destroyed them)
The issue with my unit is, that when I turn it on, I see a green led for lets say 2 seconds, no screen and no power (unit is really off). Therefore I have checked all SOT23 elements.
I have looked-up up almost all data-sheets to see which IC's are used and next is to figure out why some voltage lines are not comparable with a post earlier in this threat.

Luckily I recently purchased a toneohm 850. 1 problem, I never ever used such a device, so I need to figure out how to trace to the broken component.
I already removed CR9, C79 and C67 (randomly -> goose-chase). But I need to do this more structured -> Toneohm.

I have some questions for here on the board already:
1. What are these components (ideally with link to a data-sheet):
Q12, Q13 -> Code 337 -> FDN337N -> N-Channel Enhanced Mosfet + body diode -> Cannot find any data-sheet
Q20, Q21, Q43 -> Code 338 -> NDS338N -> P-Channel Enhanced Mosfet + body diode -> Cannot find any data-sheet
U11 -> Code S08H -> No Idea (AND port????)

2. What is the difference between VR05 and U04 (why is one name with a "U" and the other "VR"):
VR05 ->Code 8H -> MMBZ5233BLT1G -> Zener Voltage Regulators 225 mW SOT−23 Surface Mount
U04 -> Code R1E -> LM4041 -> LM4041-N-xx Precision Micropower Shunt Voltage Reference

3. Is this part a correct replacement for the white capacitors (high precision) -> C27 and C36
Code 223 KZS -> Kemet SMC F125PP223J100
(Original part is in PL housing, but that seems not for sale, however size is then upgraded to PP, SMC series, 223 matches. However KZ is still unknown in code name) -> Any help would be highly appreciated!

@Nixxon:
If your unit is not doing anything anymore, check if U17 is actually giving juice (even when powered off.
U17 =  Code PCYI -> TPS770 -> Power 5V   ULTRALOW-POWER 50-mA LOW-DROPOUT LINEAR REGULATORS

Tomorrow I will try to find my shortage with my toneohm and once fixed I will dig into this unit a little further.



 

Offline ElecSeb

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Re: Fluke 289 not quite sorted.
« Reply #121 on: October 24, 2018, 12:57:59 pm »
3. Is this part a correct replacement for the white capacitors (high precision) -> C27 and C36
Code 223 KZS -> Kemet SMC F125PP223J100
(Original part is in PL housing, but that seems not for sale, however size is then upgraded to PP, SMC series, 223 matches. However KZ is still unknown in code name) -> Any help would be highly appreciated!

Update from Kemet concerning KZS:
Please find below the explanation about the marking for our SMC series:

  • 223 is the tolerance code for 0.022uF
  • K is the capacitance tolerance code – +/-10%, but as per our catalog we not manufacture only +/-5%, +/-2.5%, +/-2%,
  • Z is the code for the voltage means 50VDC
  • S stands for SMC

I suppose that the correct PN would be SMC5.7223(1)50J33(2)
Where:
  • 1=J (5% -> which is the only one on Farnell)
  • 2=Just packaging -> not important for ordering

SMC5.7223J50J33


« Last Edit: October 24, 2018, 01:01:39 pm by ElecSeb »
 

Offline ElecSeb

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Re: Fluke 289 not quite sorted.
« Reply #122 on: October 27, 2018, 06:51:37 am »
@Nixxon any progress?
 

Offline nixxon

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Re: Fluke 289 not quite sorted.
« Reply #123 on: October 27, 2018, 07:39:35 pm »
@Nixxon any progress?

Not yet. I am figuring out how stuff works by studying the Fluke 27 Service Manual. That manual includes schematic diagrams as well.

I am also studying how graphical LCDs work, possibly gaining useful knowledge by reading links like:
https://www.microcontroller-project.com/128x64-graphical-lcd.html this one has a 20-pin connector as does the 287/289 320X240 pixel LCD display. I wonder how similar the pinout is.

And why do some graphical LCD's, like the Nokia 84x84 pixel displays, only need 8 pin connectors to work? I will have to read more about this stuff. This could be a start: https://learn.sparkfun.com/tutorials/graphic-lcd-hookup-guide/all

It looks like the LCD flat flex connector traces lead go to the area close to the PCB flip side MC9328MXS chip that includes an LCD controller. I guess I have to study the pinout and do some measurements.
https://www.nxp.com/docs/en/data-sheet/MC9328MXS.pdf

The i.MX Family of applications processors provides a
leap in performance with an ARM9™ microprocessor
core and highly integrated system functions. The i.MX
family specifically addresses the requirements of the
personal, portable product market by providing
intelligent integrated peripherals, an advanced processor
core, and power management capabilities.
The MC9328MXS (i.MXS) processor features the
advanced and power-efficient ARM920T™ core that
operates at speeds up to 100 MHz. Integrated modules,
which include a USB device and an LCD controller,
support a suite of peripherals to enhance portable
products. It is packaged in a 225-contact MAPBGA
package
« Last Edit: October 27, 2018, 09:01:16 pm by nixxon »
 

Offline ElecSeb

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Re: Fluke 289 not quite sorted.
« Reply #124 on: October 28, 2018, 07:41:30 am »
Since I am not that far with my unit I cannot do this (yet).
But why not using your (scope) and test the signals from the connector and sees what comes up?

Furthermore, some posts earlier you mentioned that your device did not power on anymore. Got it fixed?
 


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