Fluke 89 IV - powers up, measures nothing - Page 1
Forum section: electronics / repair

author: asdqwerty
author_rank: Contributor
timestamp: June 05, 2016, 05:53:17 pm
content: Fluke 89 IV:Last time it was successfully used, it was used to check 3~ capacitors and voltage.Some days later it was to be used to measure some resistance.But it shows 0.00 ohm, it beeps when switching to beep mode. It should read OL, before start.Switching to voltage gves 0.00.Althoug at times, it might rush around displaying any number, both it resistance and voltage mode. But for the most 0.00 and it does not matter what the test leads do. Open, connected to something or shorted.Fuses are checked, batteries changed. Still the same.So it seems like something in the input stage might have a break / gap.Tested with a different ohm-meter, by setting one test lead in the input-socket, and followed the pcb. I got a reading in front or after all the components it seems. Nowhere there was OL, it varied from few ohm to a lot of ohms. Don't know if its a lead...Anyone have any idea of which component to investigate more or try to change??There are pictures of the 89 PCB on google and this site.

author: Monkeh
author_rank: Super Contributor
timestamp: June 05, 2016, 05:56:57 pm
content: Take the MOVs out and see what you get.

author: retiredcaps
author_rank: Super Contributor
timestamp: June 05, 2016, 06:13:42 pm
content: I'm having a hard time following what works and doesn't. As such, let's get a baseline.Q1. If you measure a 1.5V AA cell, do you get 1.5V or 0.0V?Q2. If you short the probes with meter set to DCV, do you get 0.0V?Q3. If you short the probes with meter set to resistance, do you get roughly 0.2 ohms?Q4. If you remove the leads with meter set to resistance, do you get 0L?Q5. If you measure a 1k ohm resistor, do you get 1k ohm?

author: asdqwerty
author_rank: Contributor
timestamp: June 05, 2016, 07:03:31 pm
content: Q1: 0.0VQ2: ~0.0V -> no change with probes shorted or notQ3: 0.00 - same with probes open or removedQ4: No, it says 0.00Q5: No, it says 0.00Resistance reads 0.0 , while VAC and VDC may have the last digits run up or down.Holding "hold" while power up shows the lcd-dispay test.I think the meter is working, but there is a gap in the signal path..Also tried the mA and A, with the current in a ledflashlight.No readings.So it seems all 4 inputs are out of order, or the one thats common for all...

author: retiredcaps
author_rank: Super Contributor
timestamp: June 05, 2016, 07:50:07 pm
content: Well, if we use this picture fromhttps://www.eevblog.com/forum/repair/fluke-89-iv-repair-after-input-overload/as a reference, check the following components all "in-circuit".Q6. The 1k fusible resistor (circled in green) should read 1k ohm using another working multimeter.Q7. The three green resistors (circled in blue) marked 100k ohm should read 100k.Q8. The yellow component (circled in yellow) with a cut through it is a spark gap. It should read 0L or open with another working meter.Q9. The two red components (circled in red) are MOVs. They should read 0L or open with another working meter.Q10. The brown/grey component (circled in brown) between the fusible resistor and 100k ohm resistor is a PTC. It should read around 1k ohm.Report your readings for Q6-Q10.

author: retiredcaps
author_rank: Super Contributor
timestamp: June 05, 2016, 07:58:36 pm
content: @asdqwerty, please post clear focused pictures of YOUR board so we can see if there are differences. Please provide pictures of both sides of the pcb and one close picture of the COM jack solder area (i.e. 3 pictures in total).

author: asdqwerty
author_rank: Contributor
timestamp: June 05, 2016, 08:53:18 pm
content: Q6: Reads 3.5 Kohm - it is marked 3.5Kohm alsoQ7: They read 100KQ8: Says OLQ9: The one closes to the yellow with a gap read 11.6Mohm and 11.9Mohm when changing polarity. The other one is OL.Q10: Reads 1.15KohmAll measured with a Fluke 189.Its a slightly different PCB it seems.BTW thanks for taking your time.

author: retiredcaps
author_rank: Super Contributor
timestamp: June 05, 2016, 09:01:40 pm
content: Quote from: asdqwerty on June 05, 2016, 08:53:18 pmLooks like Monkeh has the right idea. The MOV reading 11.6M ohm might be bad. Remove it has Monkeh suggests and retest Q1-5. Also measure the removed MOV out of circuit just in case something in-circuit is affecting the resistance measurement. If the MOV still reads 11.6M ohm, it is definitely bad.

author: retiredcaps
author_rank: Super Contributor
timestamp: June 05, 2016, 09:04:27 pm
content: BTW, the contacts on the rotary switch could use a good cleaning with IPA (unless it is light photography trick?). Another reason to see pictures of YOUR pcb and not one already posted here or on the Internet.

author: asdqwerty
author_rank: Contributor
timestamp: June 05, 2016, 09:09:55 pm
content: One more picture

author: asdqwerty
author_rank: Contributor
timestamp: June 05, 2016, 09:18:12 pm
content: Another one

author: retiredcaps
author_rank: Super Contributor
timestamp: June 05, 2016, 11:41:46 pm
content: Quote from: asdqwerty on June 05, 2016, 07:03:31 pmHmm, I missed your edited statement above. Let's see if removing the suspect MOV first fixes V/ohm. Then you can retest the current measurements. One problem at a time.

author: asdqwerty
author_rank: Contributor
timestamp: June 06, 2016, 09:16:07 am
content: I removed the actual MOV. It gives a readout OL when tested.Placing the test-probes on the soldering points of the MOV gives 11,4Mohm, so thats where it came from.I then put back the MOV. No change.When putting the multimeter on VAC, it says OL for a short while, then displaying results in the range of 450-500 V, when test-probes are not connected.VDC = 0.00Ohm = 0.00

author: Monkeh
author_rank: Super Contributor
timestamp: June 06, 2016, 09:18:59 am
content: 11Mohm sounds familiar.Put it in VDC and manually change the range, see if you get sensible readings.

author: retiredcaps
author_rank: Super Contributor
timestamp: June 06, 2016, 09:24:13 am
content: Regarding the dirt on the your 89IV rotary switch as per your pictures, seehttp://mrmodemhead.com/blog/fluke-83-iii-rotary-switch/Give them a clean.

author: retiredcaps
author_rank: Super Contributor
timestamp: June 06, 2016, 09:35:17 am
content: Quote from: asdqwerty on June 06, 2016, 09:16:07 amThose two soldering points should definitely read open circuit.

author: Monkeh
author_rank: Super Contributor
timestamp: June 06, 2016, 10:33:57 am
content: Quote from: retiredcaps on June 06, 2016, 09:35:17 amIf the meter is switched on at the time, you should read across the input impedance - 11.4Mohm is not far off the mark. Assuming it's a single MOV design, not the series arrangement some Fluke models use. I'm not familiar with the specific circuit here, but that figure is.. rather close to what I expect to see across the input.

author: asdqwerty
author_rank: Contributor
timestamp: June 06, 2016, 11:00:27 am
content: Maybe worth mentioning... the multimeter was exposed to rain late last summer. It was forgotten outdoor, and quite wet. But after drying, it has worked flawlessly since. At least 8-9 months..--So I tested more, cleaned the rotary-switch circuit, and put on a tiny solderingtip on the switch itself, in case the pressure isn't sufficient to make a steady contact. But no difference.It doesn't behave 100%the same every time:Either VDC started working, or I tested too few times.But now, VDC is working 9 of 10 times. My bench-powersupply gives 2-15VDC and it reads as expected. (auto and manually)mVDC however is steady 0.00. - It shoud read like 2900mV @2.9v - The 189 does that.Ohm-setting 99.99% of the time shows, steady 0.00 Ohm - the beeper mode beeps all the time.VAC is totally wrong. Often peaks at OL and the bar indicates >1000VOr it is around -0- , and when I try the wall-outlet it says 40-50 or 65-75 or doesn't react.Or it displays approx 450VAC with no probes, and runs up and down.Amps gives nothing. 0,0A 0,0mA -Lightbulb/led in the flashlight is lit.The measuring done with the MOV out of the pcb was done with no power attached.

author: retiredcaps
author_rank: Super Contributor
timestamp: June 06, 2016, 02:14:18 pm
content: Quote from: asdqwerty on June 06, 2016, 11:00:27 amCan you remove the LCD from the pcb and post clear focused pictures of the front and back pcb? After I see pictures, I have more test/measurement suggestions.

author: retiredcaps
author_rank: Super Contributor
timestamp: June 06, 2016, 03:14:36 pm
content: Can you also replicate my 4 measurements using just 1 set of probes shown in the pictures? Assume my 187 = non working 89IV and my 77 III is the "good" meter.

author: asdqwerty
author_rank: Contributor
timestamp: June 06, 2016, 04:03:57 pm
content: Here are more pcb pictures - part 1

author: asdqwerty
author_rank: Contributor
timestamp: June 06, 2016, 04:06:20 pm
content: part 2

author: asdqwerty
author_rank: Contributor
timestamp: June 06, 2016, 04:10:31 pm
content: Measurements

author: asdqwerty
author_rank: Contributor
timestamp: June 06, 2016, 04:23:14 pm
content: Additional comment:Measurement picture 2:If I on the faulty 89IV press "range" and cycle through the manual ranges, it affects the readout on both meters.Like:519K - 1.13Vdc0,12M - 0.38Vdc2.44K - 4.83Vdc37.5K - 2.83VdcAuto - as pictureIt also had a small impact of the current measurement, leading to decreasig current to almost zero.

author: retiredcaps
author_rank: Super Contributor
timestamp: June 06, 2016, 04:30:28 pm
content: I need a break to digest all this. I'm participating on your 89IV, defective BM-235 and now Velleman 9912 all at the same time. It is all starting to blur together.I'm also gone for a few hours later this afternoon.

author: 4thDoctorWhoFan
author_rank: Regular Contributor
timestamp: June 06, 2016, 04:31:31 pm
content: Going by your pictures, the input block seems to be very dirty. You might have some contamination within or even under the input block especially since you mentioned it got wet.I would remove the input block and give it a good cleaning along with the PCB under the block. Or leave the input block connected and submerge it in some IPA and let it soak for a little while. Make sure you let it dry before retesting.

author: retiredcaps
author_rank: Super Contributor
timestamp: June 06, 2016, 04:37:57 pm
content: Quote from: 4thDoctorWhoFan on June 06, 2016, 04:31:31 pmGood suggestion. I totally forgot to suggest that. Seehttp://mrmodemhead.com/blog/gallery/fluke-189-clean-up/

author: asdqwerty
author_rank: Contributor
timestamp: June 06, 2016, 04:41:46 pm
content: The input-block is the part where the water entered the 89, and also the part where it was most wet.. and the only part not totally disassembled..I'll give it a look..

author: retiredcaps
author_rank: Super Contributor
timestamp: June 06, 2016, 04:43:23 pm
content: Note the use of paper towels soaked with IPA and then cotton buds to dry.http://mrmodemhead.com/blog/wp-content/gallery/f189_00/F189_021.JPGBTW, I'm now reminded that modemhead fixed a 187 that had wonky input jacks. It was a mechanical lug/broken solder problem. Similar to his blog post belowhttp://mrmodemhead.com/blog/fluke-80-series-jack-assembly-rebuild/I'm not saying your 89IV has wonky input jacks because your VDC seems to work 90% of the time.

author: retiredcaps
author_rank: Super Contributor
timestamp: June 06, 2016, 04:45:59 pm
content: Free_electron fixed this Fluke 189 wrt to the input jack block.https://www.eevblog.com/forum/repair/fluke-189-teardown-repair/

author: asdqwerty
author_rank: Contributor
timestamp: June 06, 2016, 05:03:01 pm
content: I can easily get a good reading with another ohm-meter, from within the inputblock to the rear side of the pcb, or to the MOVs or resistors. So I guess it is something else.. Worth a try though..Thanks for all the inputs anyway

author: retiredcaps
author_rank: Super Contributor
timestamp: June 06, 2016, 08:09:29 pm
content: Quote from: asdqwerty on June 06, 2016, 11:00:27 amI'm just curious how you dried it? Air dry or did you scrub the entire pcb with 91% IPA? How did you get the water out of the big ICs?

author: asdqwerty
author_rank: Contributor
timestamp: June 07, 2016, 05:46:14 pm
content: I remember it was most water around the input-block, so I guess I was shaking the pcb and then using a hot-air blower to dry that part, and some paper-towels.No IPA, only air. Can't remember I spent time drying other parts. Maybe it was positioned in such a way most water was in the bottom...It was left outdoor on a friday, I got it back following monday, can't remember when the rain set in, or what time that other guy found it. But it sure was wet for many hours.But since it powered-up and started working after some drying, I have just forgotten about the drying process. Only remember I spent some time with the input-block. And I'm quite sure I removed the LCD, and if it was water there I must have used paper and hot air..

author: retiredcaps
author_rank: Super Contributor
timestamp: June 08, 2016, 02:26:55 am
content: Any pictures or results from taking apart and/or cleaning the input block?

author: retiredcaps
author_rank: Super Contributor
timestamp: June 08, 2016, 02:29:28 am
content: Quote from: asdqwerty on June 06, 2016, 04:23:14 pmWell, at least the readings aren't 0 ohms. The readings, obviously are way off, perhaps due to contamination on the pcb or input block?

author: macboy
author_rank: Super Contributor
timestamp: June 08, 2016, 04:28:44 pm
content: The 89 IV has a lifetime warranty. Why are you messing about with it?

author: retiredcaps
author_rank: Super Contributor
timestamp: June 08, 2016, 07:25:12 pm
content: Quote from: macboy on June 08, 2016, 04:28:44 pmI see a lot of people make this common assumption about Fluke's lifetime warranty. Fluke's "lifetime" is a marketing term. Details in screenshot below.

author: asdqwerty
author_rank: Contributor
timestamp: June 09, 2016, 06:41:39 pm
content: I called Fluke, asking for advice. They said this unt is more than 15 years old. It better to buy a new than sending in for repair. Nobody said anything about warranty.--I have not disassembled the inputblock. It seems to be a compact-piece, and has 8 soldering point.However, when I take another ohm-meter and put one test probe in the inputblock, and the other probe on the soldering-point on the rear, or a component along the input-stage, I get very low ohm reading, so I concluded there's no problem along that signal path...(?!)

author: retiredcaps
author_rank: Super Contributor
timestamp: June 09, 2016, 07:41:02 pm
content: A lot of those side by side readings are obviously wrong suggesting there might be leakage current somewhere. If it were my meter, I would have already desoldered the input block and cleaned it. I buy abused/used meters and have seen what pcb contamination, however small and not visible to the eye, can do in terms of funny readings. There are a number of cases here where we have helped users fix their multimeters with funny readings just by a good IPA bath.You have nothing to lose but 15 minutes of your time because this Fluke is not under warranty.

author: asdqwerty
author_rank: Contributor
timestamp: June 10, 2016, 02:01:48 pm
content: That's right. It doesn't work as is, so it can't be any worse.I'm gonna desolder the input block and give the pcb a good IPA bath.

author: retiredcaps
author_rank: Super Contributor
timestamp: June 10, 2016, 02:53:41 pm
content: Quote from: asdqwerty on June 10, 2016, 02:01:48 pmI'm not saying this is going to work, but if we eliminate this as a possibility, then we can move on to other things. If the readings also change that gives us a clue too.BTW, I still can't shake the feeling those two solder MOV points should be open circuit when the 89IV is powered off. However, I have been fighting a cold for almost 5 weeks so I may not be thinking clearly or I just don't understand how it works in the 89IV. I have no formal electronics education.

author: oldway
author_rank: Super Contributor
timestamp: June 10, 2016, 03:30:56 pm
content: My 87IV had more or less the same problem: no reading at all.The black binding post of input block was defective (broken and interrupted)As this input block is very expensive and I don't use current inputs, I mounted the input block of the wrong way (rotated of 180°) and it work again. (see picture)

author: Monkeh
author_rank: Super Contributor
timestamp: June 10, 2016, 05:16:19 pm
content: Quote from: retiredcaps on June 10, 2016, 02:53:41 pmNo power attached is not necessarily the same thing as being switched off.