Fluke 789 Repair

[npnpnp]

Hey everybody,
I recently got a damaged Fluke 789 Processmeter.

The device powers up and only shows "unCAL" -  as far as I know this is the common indicator of this meter that something inside is definitely wrong.

Inside there is a black spot on the PCB next to the fuse. I think some traces and/or devices were broken due to a shock.
I already tested the obvious traces and devices, everything seems to be ok. Moreover, the device does not measure anything, but the Loop Power function provides a voltage.


I already found a similar topic:
https://www.eevblog.com/forum/repair/fluke-789-repair-safety-implications/

Unfortunately, the damage of my meter is not located at the same spot.

Do you guys have experience in reparing this meter or do you have more knowledge about the wiring inside the PCB? I know this is a very specific question.
I am not able to follow the trace at this section and tell if there should be a connection or not. Fluke does also not provide schematics.


Best regards

[coromonadalix]

Damn  a delaminated board in two cases, corrosion ??  leaked batteries ??


As i see it you vave 3 vias, 2 on the same cr1 pad and the small one in the center,  you have to know where it / they goes ...  ask the linked thread  "atsthng" guy, maybe he can help to trace it

Sometime you can put a small very bright flashlight against the board and see the pcb traces layers and see where it can go ...

[npnpnp]

According to some black marks inside, there seemed to be an electric shock. atsthng also discovered a wrong 10A fuse inside his meter (should be 440mA). I sent a message to him.

I think, the small via in the center is damaged. I managed to contact it from the other side of the PCB and there does not seem to be a trace to any other point. 

[Solderingfanatic]

Well, I got a used 789 Fluke processmeter last year. Working fine, although I didn't use it frequently, when suddenly, stopped working. Something like losing battery contact, the LCD going on/off. After some time it simply died completely.  I dissasemled it completely, till the last screw, found absolutely nothing. Note that it was not burned or something similar. Anybody has some repair manual or electric diagram available? I will post pics of the PCB next week.

[jorgeescobar]

hola, me podrías ayudar, tengo el mismo fluke y se quemo el transistor q20 y no se cual es, ya que se reventó, tu me podrías ayudar con la numeración del transistor?

[Ugur]

Check if CR1 and CR2 are good. CR1 one end should be connected to COM, the other end should be connected to A/Loop PWR (W9) and a pad under the selector switch.