Fluke 189 series 1 DC voltage is off

[tibimakai]

I have just realized that my meter is off, when I measure the car's battery, and I can't imagine how that happened.
I also have a 87, and when I doubled checked the voltage, the 87 was showing 3.5V higher, than the 189. Most likely the 189 is off.
Where should I start with the 189?
Switched leads between the two meters, but nothing has changed.
I have not opened it yet.
Any help would be appreciated.

[stj]

is it under warranty?
if not then start by checking the MOV because they are known to get leaky over time.
it may also damage the big current-limiter resistor.

[tibimakai]

MOV?! What exactly is that?

[redwire]

Take it apart.
It could be the supercap is leaking and taking the piss on the board. Or a protection component (clamp transistors) are damaged.

What does it read on Ohms with the leads not connected to anything?

Typical pics of 189: http://mrmodemhead.com/blog/gallery/fluke-189-clean-up/
Supercap thread on 289: https://www.badcaps.net/forum/troubl...repair?t=72162

[tibimakai]

I will check when I get home, but I remember that I have measure the Ohm scale with the 87, and it was reading 15.3Mohm instead of 10Mohm.

[tibimakai]

Opened it and found at least one resistor blown, with trace lifted as well. The one next to it, in series reads 1.152KOh. I'm not sure, if that OK, or not.

[redwire]

Those appear to be the shunt resistors for the uA and mA ranges? The bridge rectifier and diode are supposed to clamp and protect the shunts and just blow the 440mA fuse... so I don't quite understand what went wrong here.
One horizontal resistor going to the via I see in another pic is a blue precision 100Ω. There should be a 1Ω somewhere... the badly smoked one I cannot see clearly in any pics maybe 251x? or something written on it.

I have a Fluke 189-II service manual 2008 with schematic- but it's different than your pic. They might have fixed an error or beefed them up.
Current shunts:
R167 100Ω 1% 1W
R165 1Ω 5% 2.5W
R5 0.010Ω 2% 1W WW big shunt for 10A range

I can't see them causing problems for the Voltage and Ohms functions. Unless it's the leakage current from the shrapnel

[tibimakai]

The replacement supercap in the 289 thread is the same part number for the 189 as well? Mine is growing something as well. I think it would be time to replace that.

[stj]

the blue parts are MOV's (varisters) and should meter open-circuit.
whats printed on the red one?

[redwire]

The replacement supercap in the 289 thread is the same part number for the 189 as well? Mine is growing something as well. I think it would be time to replace that.

I believe it's the same supercap used in Fluke 189, 287, 289 - but not 100% sure.
07/2023 Elna is phasing out making coin supercaps, they are NRND but some production and stock available.
Elna 0.2F 3.3V DSK-3R3H204T614-H2L new p/n is RSCSK2043R3D01004T. Mouser 555-DSK3R3H204T614H2
Elna 0.33F 3.3V DSK-3R3H334T-HL new p/n is RSCSK3343R3D02008T. Mouser 555-DSK-3R3H334T-HL (thicker 2.1mm vs 1.4mm- fits)

I would first get the voltage channel working. The damaged current shunt resistors are on a different (current input) channel to the big IC so the two problems are not related that I can see, which is a bit puzzling.
The red MOV is an old GE part and must be a different voltage than the custom blue Epcos S05K575. For the old Fluke 87's it was V575LA10P or V910LSX1399 5mm red 910V 1mA almost same as the Epcos part.
I would guess either a MOV is leaky or the protection clamp is damaged, for the voltage channel - leakage would make it read lower V.

[tibimakai]

The red one measures 1.107Kohm.
I was measuring parasitic drain at my wife's CRV, maybe I did something stupid and I did not even realize?!
What should I look for at the voltage scale?
MOVs show OL with the Ohm meter, except the red one.
Which one is the protection clamp?

[stj]

whats printed on the other side of the red part?
btw, all 3 are protection - that whole area below the switch is.
i suspect it's the same part as the blue ones - i hope anyway.
i have the schematic of the series2 here.

[redwire]

I found a Fluke 189-I board pic with the two burnt resistors "2611" for 2k61 1% and "1001" for 1k00 1%, in series with each other? and then PCB trace to the red part. I forgot the blue (foil?) ones, I thought a Vishay line but 1206 1% would be i.e. CRCW12062K61FKEA. It's probably better than 1% part though.
I don't see those resistors used in a Fluke 189-II. I wrongly thought they are the mA-range current shunts- but those are 1R (big black through-hole) and 100R 1W both located on the other side of the board.

For curiosity, can you tell us ALL markings on the red part? I did see "LF" for Littelfuse. Apparently it is not a MOV, but is a PTC (also used in 87-I) and it's normal to read ~1.1kΩ resistance across it - so it looks fine right now- but failed at its job so the 189-II ditched it lol. I think early Fluke DMM protection was a bit unrefined.
For reference data I have: Fluke p/n 1277360 THERMISTOR, POSITIVE, 1.1kΩ, +-20%, COATED, RADIAL Original G.E. YS3961, possible substitute Amphenol YS4020.

So anyway, back to the reading low V problem... I doubt it's the burnt resistors but not sure. I would replace them, clean up the smoke with IPA and a Q-tip, and see where that takes us? Red part seems OK.
Otherwise, it's the protection clamp and with no schematic a little hard to point those parts out.

[stj]

the carbon that was the board could be conducting between traces

[tibimakai]

That is a great picture!! Thank you for that.
What wattage could those have, 0.25W?
I will post a picture with the red part, when I get home.
Thank you guys, it is much appreciated.

[redwire]

They look like size 1206 [Metric 3216] 1/4W resistors, Fluke uses Vishay/Dale CRCW series so I would guess: CRCW12062K61 and CRCW12061K00.

To burn them up, say at 1W would be ~82V for them. 12V work could not have cooked them.

[tibimakai]

On the back of the red part is D44, not sure what that means. I did not se the LF logo.
Thanks for the resistor info.
What do you think I should do, order and replace those resistors and we go from there, or should we do more diagnosing, before I order parts?

[stj]

clean it up with IPA - see if the board is damaged or it's just soot around the resistors

[tibimakai]

The PCB is black under that resistor(the resistor's shape), but it is not conductive. I also managed to pop up the PCB with the hot air station(yeahh).
I have just realized that that one of the big fuses are open.
I can swear that it was good when I started.
I guess I will place an order for those two resistors, and a fuse, and we go from there.
Will be back, when I have replaced those components.
Since the trace is lifted and one side is gone, should/could I use through hole resistors?

[VoicesFYC]

not sure if this will help... but since i'm pretty good with fluke meters from time to time i went looking for a service manual.... welp good luck with that...i don't think fluke made one..or if they did it is in-house ONLY... but i did come across something that MIGHT help... just not totally sure so i will post it here... BE ADVISED it's Both Chinese and English...so don't shoot me over it....it's all i could find on the 187 & 189 fluke meters . hope this does some good . Daniel. https://www.eevblog.com/forum/repair...attach=1054516 click this to download the PDF they made.