Fluke 8845A No Display

[EddyInChicago]

Hi All,

I recently acquired a Fluke 8845A that has a blank display.  Checking some test points I came across one TP that is supposed to give me 60V, but is giving me 2V instead.
I am getting about 90V at the bridge rectifier near that TP. For some reason I am not able to upload or attach a picture of the board. I get a message to contact the
ADMINISTRATOR.

All help is appreciated.

Thank you,

Ed

[EddyInChicago]

OK.....so I was able to save the photo as .PDF and upload it. Hope this helps.

[ledtester]

Don't have any info on diagnosing the PCB, but I would try testing out the meter itself using the GPIB / RS232 or Ethernet interface.

GPIB and Ethernet connectivity might require configuration you would normally do from the front panel. But you should be able to connect via RS232 using this recipe:

- use a null-modem serial cable to your computer
- connect using a terminal program set to 9600 baud, 8N1
- issue a command like *IDN? followed by CR LF and you should get back a response that begins with FLUKE,8845A,...

If you get this far I can guide you through some more commands.

Full docs are here:

https://xdevs.com/doc/Fluke/8846A/8845a_8846a_programmersmanual.pdf

[EddyInChicago]

ledtester,

Thank you for that. I will try this and see how far I can get. I've never done this before. So I'll do some research as to how to do this
procedure. Stay tuned. I'll keep you posted.

Thanks,

Ed

[EddyInChicago]

Hi All,

So I fixed the no display problem by changing out the two parts listed below:
1) NC7SZ14M5X - This is a Schmitt trigger / Inverter
2) SQ4532AEY-T1_GE3 - This is a N Channel MOSFET

When I changed those two components, I got the 60V at the test point. Display working perfectly now.
Those are the U6 and Q2, respectively.

Thanks,

Ed