Fluke 179 won't tun on

[tibimakai]

I have picked up this meter, in decent condition for $20.
It seems like, it is completely dead.
Fuses and battery are good.
After opening, I have found some transistors looking components that are shorted, but not completely. At one of them, it seems like the green paint came off at one leg and in the same spot, seems like the trace has a damage as well(maybe missing transistor leg, hard to tell).
I'm not sure what they are actually to properly test them.
They have a JC marking on them, thy could be some kind of diodes?
I can't find schematic for this meter anywhere.
I have also noticed, that the two PCB trace circles(buzzer contacts) are missing, even the traces leading to these two pads are not reaching the circles.
Another thing that I have noticed, that one of the traces that goes through a via to one of the LCD LEDs is missing. Between resistor and LED.
What could have happened here?
I have not taken any pictures yet, but I have found some picture at the eevblog.

[tibimakai]

Re: Fluke 179 won't tun on

I may have found the JC component, it seems like it's a fast switching diode, that looks like a transistor. SOT323, pin #1 not connected. BAL74W.

[stj]

Re: Fluke 179 won't tun on

your comparison photo's:
left image is gold plated, right photo is oxidised copper - both have pads.

got a complete parts side foto?

[retiredcaps]

Re: Fluke 179 won't tun on

There are at least 3 internal revisions of the 179. Each have significant changes.

Trying to remote troubleshoot using other people's pictures is like asking a surgeon to operate on you using your brother's x-rays. Post clear focused pictures of your own 179 (both sides) with the lcd removed.

There are no schematics of the 179 publicly available. I suggest you see if the oscillator/clock is running as a start.

[tibimakai]

Re: Fluke 179 won't tun on

I know, that it's not easy to diagnose something, from the distance.
I will take some pictures, when I get home.
Those pads may be oxidized, but mine are not even there.
I have to check, if the buzzer is actually there, I don't remember.

[tibimakai]

Re: Fluke 179 won't tun on

Buzzer is missing from the back cover.
Here are the pictures, taken with my phone.
Hopefully, they are clean enough. If they are not adequate, I will take new ones with my camera.
I will recheck those JC diodes.
Actually, the trace and via is not missing from the LED, it is missing from a resistor, next to the Texas Instruments IC(left upper corner).

[stj]

Re: Fluke 179 won't tun on

look at the earthing ring around the central screw hole - it shows the same difference.

nice foto - check the crystal and check for power across the tantalum smoothing caps.

[tibimakai]

Re: Fluke 179 won't tun on

Do you mean the brown color?

[stj]

Re: Fluke 179 won't tun on

forget the brown for now.
btw, on looking at the second image - broken solder joints on the vertical ceramic board where it's soldered to the main board.

[tibimakai]

Re: Fluke 179 won't tun on

I'm not sure, which one you are referring too.

[stj]

Re: Fluke 179 won't tun on

white ceramic board on the right about halfway up needs resoldering

[retiredcaps]

Re: Fluke 179 won't tun on

There looks to be a break in this copper trace right at the 9V + connector (circled in red). If yes, there will obviously be no power to the microcontroller/processor.

The meter can also benefit from a thorough IPA bath and careful inspection via 10x jeweler's loupe. See

http://mrmodemhead.com/blog/fluke-77...per-corrosion/

PS. The picture can be clearer. If I can't clearly read the writing on the pcb, it is not good enough.

[tibimakai]

Re: Fluke 179 won't tun on

I will clean it and take a good picture. Then I will check the traces.

[tibimakai]

Re: Fluke 179 won't tun on

That vertical trace, it was indeed broken.
Unfortunately joining it, did not help.
I have ran thin copper wires, through the via where the resistor goes to the top LED and where it was interrupted the trace. But still a no go.
I have made some indoor pictures, because outside is way to hot. Hopefully they are good enough.
The quartz does not show oscillation, only some millivolts.
The digital main IC is a Texas Instrument M430F437.
If I understand correctly, pin #1 should have the input voltage and there is 0V.
https://cdn.badcaps-static.com/pdfs/...487e34355c.pdf

[keeney123]

Re: Fluke 179 won't tun on

I have circled places on the board that had been either dinged or rework other than what you did. The run seems to go through the LEDs. Have you check to see if one is bad? One place on the front in the upper left hand corner on a run I have circle going to what appears to be a transistor may be broken at the transistor. I have not traced out the output of that transistor to tell were it goes.

[tibimakai]

Re: Fluke 179 won't tun on

Both LEDs turn on, when I check with the meter.
Actually I have attempted those repairs. The first two are actually not important, because after connecting them, I have realized, that they go to the buzzer.
The transistor(which seems to be a diode though) repair, may not be good. To me, it seems like that leg is completely missing. The solder, may still touch that broken leg,, because when I measure it, shows as the others. If we manage to repair it, I will replace that diode.

[keeney123]

Re: Fluke 179 won't tun on

That diode has three legs? To me it looks like the run that comes into the middle of the "diode?" has got a break in it near the "diode?"

[tibimakai]

Re: Fluke 179 won't tun on

It has two legs.

[keeney123]

Re: Fluke 179 won't tun on

So the run going to the middle of it goes somewhere else? The run on the left side of the diode.

[tibimakai]

Re: Fluke 179 won't tun on

There are see, only diode sign.