Fluke 187/189 repair

[Syzeryuino]

I recently picked up a fluke 187 for 40$ from an online store in my country as not working

The meter doesnt start up at all, after opening it i discovered one of the caps was blown(on the last pic), thinking it was an easy repair i replaced it. but it doesnt do anything, does anyone have a solution or a service manual of some sort for this meter?

[aqibi2000]

What is the resistance across the points where you have installed the new capacitor?

[daisizhou]

please check http://bbs.38hot.net/forum.php?mod=viewthread&tid=853404&extra=page%3D1

[Syzeryuino]

What is the resistance across the points where you have installed the new capacitor?

It was 1.1 Mega ohm

please check http://bbs.38hot.net/forum.php?mod=viewthread&tid=853404&extra=page%3D1

Oh wow didnt know this exist, thanks

[daisizhou]

Check the manual carefully before repairing.

[Syzeryuino]

Check the manual carefully before repairing.

this might be asking too much at this point, but do you have the english version, my mandarin is really limited

[shakalnokturn]

There are signs of residue/corrosion mainly around the 93C56 and on both sides of PCB.
I'd start with a good wash-down of whole PCB with toothbrush.
Next start checking power supplies.

[daisizhou]

Please use google translate.Just understand the circuit principle

[daisizhou]

It is recommended that you use (washing water) to clean the motherboard, especially those with blue color corrosion, focus on cleaning

!! Attention!! (Plate washing water) is not alcohol.

It is a mixed liquid specially designed for cleaning PCB circuit boards.
If you use alcohol, it will corrode the pads and other places and leave white marks. It is strongly recommended that you do not use alcohol to clean

[kripton2035]

auto-translated documents in english

[Syzeryuino]

There are signs of residue/corrosion mainly around the 93C56 and on both sides of PCB.
I'd start with a good wash-down of whole PCB with toothbrush.
Next start checking power supplies.

ok, will do!

It is recommended that you use (washing water) to clean the motherboard, especially those with blue color corrosion, focus on cleaning

!! Attention!! (Plate washing water) is not alcohol.

It is a mixed liquid specially designed for cleaning PCB circuit boards.
If you use alcohol, it will corrode the pads and other places and leave white marks. It is strongly recommended that you do not use alcohol to clean

i dont think i have any of that, or they sell those things here, do you have an alternative like ethanol or wd40? or should i just wash it with water and let it rest in an oven?

auto-translated documents in english

wow man, thanks alot for that

[joeqsmith]

During your attempt to repair the meter, how did you manage to damage this area? 

[daisizhou]

It is recommended to use a knife to physically clear the black area
Seeing the PCB
After seeing the PCB substrate layer thickness
Stop after seeing the PCB base layer
Then use insulating oil to protect

[goaty]

Very interessting PDF with good points to start.
I think you need to check from page 14 on the power supply first.

Because your damaged cap is exactly at the power input.
So that and the LT1307 etc are probably the thing to check.

(Man I wish they would teach more english in China. It´s really hard to understand sometimes.)

[Syzeryuino]

During your attempt to repair the meter, how did you manage to damage this area? 

the burnt pictures ( the small one ) is not mine but from the instructions , maybe its a fluke that's being serviced by the manufacter

It is recommended to use a knife to physically clear the black area
Seeing the PCB
After seeing the PCB substrate layer thickness
Stop after seeing the PCB base layer
Then use insulating oil to protect

ok, i have cleaned the pcb and start probing around lt1307 and found that the voltage input of the lt1307 is ~100mv ( probably an error on the meter ) so my question is, what is the component between the photos? thanks

Very interessting PDF with good points to start.
I think you need to check from page 14 on the power supply first.

Because your damaged cap is exactly at the power input.
So that and the LT1307 etc are probably the thing to check.

(Man I wish they would teach more english in China. It´s really hard to understand sometimes.)

thanks for the advice, but i have the same question for you same as @daisizhou what's the component  that cause that much voltage drop.

[shakalnokturn]

The lowest component marked, the one with 6V on one side nothing on the other is an inductor to filter supply to the LT1307.
If the inductor has fused consider the LT1307 may be damaged.

[goaty]

You can for test bridge the inductor, but make sure not to use batteries but a current limited power supply !

Later, maby I can try measure inductor in circuit if it is possible on my 189, so you can know the inductance.

[shakalnokturn]

I'm trying to imagine the abuse this meter has been through.
There's a diode across the battery input I imagine it's only for reverse polarity protection.
The fact that this tantalum capacitor and inductor before the LT1307 blew would point to an overvoltage, which would mean someone with a supply other than the normal batteries was careless.
If you're lucky enough that happened before the person had time to wreck other things by scratching deposit between IC pins with the DMM powered...

[joeqsmith]

During your attempt to repair the meter, how did you manage to damage this area? 

the burnt pictures ( the small one ) is not mine but from the instructions , maybe its a fluke that's being serviced by the manufacter

LOL.  Yeah, I wasn't paying attention to who the posts were from. 

[goaty]

The chip inductor on 189 measure in circuit 5 to 5,5µH.

[Syzeryuino]

The chip inductor on 189 measure in circuit 5 to 5,5µH.

thanks goaty ,after shorting the inductor for a split second the meter came to life!, ill look for replacement right away.

I'm trying to imagine the abuse this meter has been through.
There's a diode across the battery input I imagine it's only for reverse polarity protection.
The fact that this tantalum capacitor and inductor before the LT1307 blew would point to an overvoltage, which would mean someone with a supply other than the normal batteries was careless.
If you're lucky enough that happened before the person had time to wreck other things by scratching deposit between IC pins with the DMM powered...

i know right, just because fluke dmm are tough doesnt mean you need to abuse it like that. but this is pretty common in my country i guess. lots of fluke multimeter become black ( mine too before i wash it!).

During your attempt to repair the meter, how did you manage to damage this area? 

the burnt pictures ( the small one ) is not mine but from the instructions , maybe its a fluke that's being serviced by the manufacter

LOL.  Yeah, I wasn't paying attention to who the posts were from. 

happens to all of us hahahah, just dont lost focus when fixing electronics!

[goaty]

after shorting the inductor for a split second the meter came to life!, ill look for replacement right away.

That doesn´t sound too good. So it died again ? Hopefully you limited the current...

[Syzeryuino]

after shorting the inductor for a split second the meter came to life!, ill look for replacement right away.

That doesn´t sound too good. So it died again ? Hopefully you limited the current...

sorry for phrasing it incorectly, i shorted it with twezers, and once it turned on i quickly pull it away

edit : was limiting the current to 300mA too much? it was on for less than a second.

[Black Phoenix]

edit : was limiting the current to 300mA too much? it was on for less than a second.

The question is now to know how much current is present in that part of the circuit to know if you overshoot or not. But I think not, you just made a little "overclock".

[Syzeryuino]

edit : was limiting the current to 300mA too much? it was on for less than a second.

The question is now to know how much current is present in that part of the circuit to know if you overshoot or not. But I think not, you just made a little "overclock".

after i replaced the broken inductor is it safe assume its fixed? like will it blow up if i put a battery in it? and the inductor that goaty identify is 5~5.5uH , can i use 5,7uH because its the only one i can find.