Fluke 355 DC Current Is Crazy!

[Graham_f]

I recently was given a Fluke 355 AC/DC current clamp meter...yay for me! but its got some issues.
Everything works pretty good as far as i can tell except for the DC Current measurements. The display just bounces from -107A to 466A.

any ideas where to start? i cant find a service manual for the 355 and as far as i know its never been abused. I've had a look inside and the pcb seems to be in good shape, no battery corrosion, or other damage. Pretty sure i'm the first person in there.
I'd love to get this thing working again, but its not worth the $680 fluke wants just to take a look. That doesn't even include replacement parts or work.

anyways, thanks in advance for any help you've got!

Graham 

[garrettm]

Some pictures of the inside of the meter and PCB would help for a start.

If the meter uses a hall effect sensor and it has been damaged from electrostatic discharge or through some other means, the unit is most likely BER (beyond economical repair). But if it's just an IC on the PCB, chances are good that you can fix it.

[garrettm]

Just noticed this was your first post, welcome to the forum Graham!

[Graham_f]

Thanks, I’ve been around here for a while, just never got around to signing up!

I’ll grab some pictures when I’m back at work. It did look pretty good to me, but I’m kinda new at this type of problem/repair...plus these multi-layer boards are tricky!
Most of my experience is with automotive electrical design.

[Graham_f]

so I grabbed some pictures, sorry but my phone is the only camera I have. let me know if I can get better pictures of any specific part.

https://photos.app.goo.gl/5yK5bNb5npuDmah39
https://photos.app.goo.gl/davFKutuZhwxViPb8
https://photos.app.goo.gl/m43n2SGEE7q9Zafw9

The spot that looks like it may have been messed with the the solder mounts for the main function switch. It seems to work fine so I suspect the problem is elsewhere.

https://photos.app.goo.gl/kMkqh5F94NJJVfkU8
https://photos.app.goo.gl/CRNWjFdoEJRKLwvu5

while taking photos I did notice that something was missing.

https://photos.app.goo.gl/3nxdK15aHaN1fNPC6

I then found a video on youtube that showed it to be a resistor, marked 333. I found one and tossed it in there but still no luck. The DC current measurement is still bouncing around.
Any idea where i can find some kind of schematic or test point information for this thing? I've had no luck searching.

[Graham_f]

I've looked all over the interweb and cant even find calibration information for this thing. There must be a way right?

[RAL97]

Hello, Graham, if you are still around, I also have a Fluke 355 but the jaw is damaged.