Electronics > Repair

Fluke 865 graphical multimeter


I'm looking for information on repairing a Fluke 865. I've already looked around and there's not much information on this meter:

Repair Fluke high end DMM. Got rolled on a used one.
863/867 Service Manual

Problems I've found:

* Backlight doesn't stay on after the first second or so
* ACV turns on, but doesn't actually display anything
* "Set Up" turns the meter on for a couple seconds, then it shuts off again
* Both the "Set Up" and "Component Test" functions are shifted one position to the left on the dial
* DCV has a chart that works, but the numbers don't reflect an actual measurement
* When turned to certain functions, there's an audible and perceptible click/clunk from inside
I've read that these meters can have problems with the dial (Fluke 83-III Rotary Switch) and I tried cleaning the carbon contact pads, but nothing changed. I wasn't able to completely disassemble the switch assembly because it appears to be soldered to the board.

I'm very much new to complex electronics like this and this is my first "pro" multimeter. Any and all input is appreciated. Barring repair information, any recommendations on where to send this for repair?

You don't give any history. Acquired as-is, stopped working in your possession, circumstances.....

Have you checked that the knob is correctly aligned with the rotary switch ?

The side visible on your photo is the input routing, I'd check all contacts for continuity in closed position.
It is the other side that has the more fragile contacts telling CPU what function the meter is set to, has that been cleaned too? Also I can't remember for sure if this can be misaligned or not with the other part of the switch.

Do you have another multimeter and oscilloscope available for troubleshooting?

Sorry, I didn't even think to include that information.

I just acquired this meter, as-is. I saw that it powered on when I bought it, but I didn't really know enough about it to check functionality in depth.

I'm pretty certain the knob is aligned; the PCB has the different functions silk-screened on it and there's a small pointer on the dial on the top half. The bottom half (under the PCB touching the pad contacts) can only snap on one way.

I'm not so sure now about the contacts having good continuity though. I took it apart again to test the resistance across some of the pads and now that I've reassembled it the VAC position is working, as tested on my home current (120V 60Hz). However, the logic position no longer displays anything, the setup function is still off by a position, and the backlight still doesn't work correctly. The fact that some of this changed after teardown and reassembly again suggests to me that there's still not consistent contact on the pads. All I did before was swab with isopropyl alcohol; is there a better way?

I do have another multimeter, just a cheap unit from a big box store. I've been trying to use it to work with the 863/867 service manual, but at least a few of the resistors are measuring differently than indicated.

Make sure the CPU's function selection switch is well cleaned, including the PCB not just the spring contacts.
The PCB must be clear of any black residue without removing the coating that's meant to be there.

When measuring resistances in circuit don't always expect to read the marked value, if you read higher than marked value there's usually something wrong though.


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