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Products => Test Equipment => Topic started by: Lamima on April 04, 2014, 04:45:50 am

Title: Help needed - Fluke 8840 DMM won't switch on
Post by: Lamima on April 04, 2014, 04:45:50 am

I need some help for a old Fluke 8840 DMM. It has some strange behavior after pressing the power button and perhaps somebody already knows the answer.
So, here is the fault:
After pressing the power button the display starts to flicker with a random pattern. Sometimes it flickers for 2-3 cycles (each cycle is flickering for about one second, gets dark for a shorter period and starting to flicker again) and then stays dark, some other times it is in an infinite loop of the cycles described above.

Any advices where to start my investigations?

Title: Re: Help needed - Fluke 8840 DMM won't switch on
Post by: bimj1 on April 04, 2014, 05:51:14 am

Do you hear any relays clicking when you turn it on ?

U202 the Z8 microprocessor is probably dead.

but to be sure you should probably go download the manual http://assets.fluke.com/manuals/8840A___imeng0300.pdf (http://assets.fluke.com/manuals/8840A___imeng0300.pdf) and start following the troubleshooting section

Title: Re: Help needed - Fluke 8840 DMM won't switch on
Post by: Lamima on April 04, 2014, 07:45:05 pm

No, there is no clicking sound at all. Hopefully the main controller is not dead - it would be a shame if the good old device is not repareable...

Title: Re: Help needed - Fluke 8840 DMM won't switch on
Post by: mzacharias on April 04, 2014, 08:58:38 pm

I would definitely re-solder all the power transformer connections. Very common problem; it happened to mine.

Some of the bad connections were not visible as such. Re-solder them all anyway. Pretty good chance this fixes yours.