Author Topic: Fluke 289 Repair  (Read 21452 times)

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Offline retiredcaps

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Re: Fluke 289 Repair
« Reply #25 on: January 31, 2014, 11:07:49 pm »
I'm glad you got it working and that the 289 seems within its specifications.  :-+

Buying something "as is" and paying a high price for it can end badly especially if the pcb sustained more damage or if the 289 required calibration.  Luckily, the input protection worked and protected the meter.

Now, let's see pictures and your repair of the Agilent and Klein.
 

Offline Priidik

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Re: Fluke 289 Repair
« Reply #26 on: August 21, 2017, 10:04:27 am »
Hi. I'm reluctant to resurrect an old thread, but I have a 289 here with the exact same HV burn dmg.
As many before me I have difficulties finding the exact same parts as the Fluke originals.
Tried random varistors, nope => crap. High capacitance range zero reading (~0.250nF) and resistances were out too for some reason, despite the varistors measuring over 1 Gohms.
So I'm thinking the originals must be very low capacitance parts.
Without varistors and with 1/4W 1k resistors in place of the PTC-s the cap zero reading w/o leads is 0.085nF. Dunno if that's ok or not. Other than that everything, including cap(at least in uF and up) range is in spec  :-+
So my question:
would it be bad idea to use GDTs (like Bourns 2095-80-BLF) instead of MOVs there? Coud it be that the right MOV with the right capacitance could be somehow compensated upstream to cancel out their impact? Like, no MOV is sub pF anyways, right?
On the other hand GDT would be slower and 'clamp' harder. Perhaps not a good idea with the Low Z function. 
Thoughts?
Thanks ahead!
 

Offline retiredcaps

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Re: Fluke 289 Repair
« Reply #27 on: August 22, 2017, 04:44:27 am »
Tried random varistors, nope => crap. High capacitance range zero reading (~0.250nF) and resistances were out too for some reason, despite the varistors measuring over 1 Gohms.
If you remove the varistors completely, do resistance measurements work properly?  If not, give an example of what is wrong. For example, if you measure a 1k ohm resistor, what reading do you get?

Quote
So my question:
would it be bad idea to use GDTs (like Bourns 2095-80-BLF) instead of MOVs there?
Yes. Changing parts that do not meet or exceed factory specs is a bad idea.  Fluke has always used MOVs so stick with MOVs.

Answer the question above and then we can proceed.
 

Offline Priidik

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Re: Fluke 289 Repair
« Reply #28 on: August 22, 2017, 01:25:21 pm »
Quote
If you remove the varistors completely, do resistance measurements work properly?  If not, give an example of what is wrong. For example, if you measure a 1k ohm resistor, what reading do you get?

Yes. Changing parts that do not meet or exceed factory specs is a bad idea.  Fluke has always used MOVs so stick with MOVs.

Answer the question above and then we can proceed.
Hey, thanks for taking time to answer.
Yes, everything I have measured is safely in spec (2-3 counts out the most). I have a recently calibrated (also adjusted) BM869 and bag full of calibrated resistors  that show pretty much bang on with the damaged Fluke.

Well, not like GDT-s are never used in multimeters. Keysight uses these in benchtops. The protection circuit could be slightly different,  and there is no Low Z function in those.
    Meeting or exceeding factory spec is how you look at it. GDT will have less capacitance, higher current rating, lower on resistance (which might be worrisome) and slower turn on, also perhaps not ideal. The slow turn on and low 'on resistance' gives me pause for now. MOVs that I have found don't work, too high capacitance. The S05K575 original could not be found, or at least I have not.
« Last Edit: August 22, 2017, 01:28:06 pm by Priidik »
 

Offline Ordinaryman1971

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Re: Fluke 289 Repair
« Reply #29 on: August 22, 2017, 01:34:55 pm »
I think the varistor should have a resistance of 1K, so there is a fusible resitor and varistor in series and each of them is 1K. Replace varistor with regular resistor for tries and see if the measurements are correct... I've replaced few of those, let me see what I've used
 

Offline iAleks

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Re: Fluke 289 Repair
« Reply #30 on: June 07, 2019, 10:40:18 am »
Hello everyone,
I'm trying to restore 289 after a strong water damage. Now 289 is turned on, the display is work half other half is hard to see, measures the voltage normally, the current measures normally, but with the measurement of resistance there is a problem..
With no connection any resistor he shows ~3,6MOhm, if i change range up too 20M or 500M he shows ~26MOhm.
I measure voltage on all ranges with 10GOhm intput voltmeter
Range   Out volt.
500       3,230
5K        3,069
50K      2,910
500K     2,749
5M        2,724
30M      2,628
50M      2,27
500M    2,627

Range 500Ohm-500K measure correct (i measure resistors with 1-5%), in range 5M he can measure resistance 1MOhm 2Mhom correct, but all above 3,6MOhm he cant see.
Here photo before and after ultrasonic clean https://photos.app.goo.gl/i1igHbYTkfpc5ZQe9
I think schematics similar to 867 multimeter https://yadi.sk/i/3GnY4aS0-KpUyg

Maybe someone at 287-289 can to measure the voltage on different ranges?
 

Offline ostapbender666

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Re: Fluke 289 Repair
« Reply #31 on: December 04, 2019, 05:10:30 pm »
Hello guys ! Need your help ! Bought a multimeter Fluke 289 without probes when you turn on the tester displays a message that the probes are incorrectly installed at all positions. I took it apart all the parts in place what parts can I check and how ? Two phototransistors each EA against each other what should be the resistance and photodiode ? I will be very happy people who was able to find a solution to this problem!Await the from you guys answer !
 

Offline ostapbender666

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Re: Fluke 289 Repair
« Reply #32 on: December 09, 2019, 06:03:58 pm »
Who can help me with this problem ? What to measure and what should show if the working condition of the radio components of this circuit ?
 


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