The Shop > Electronics & IC Programing

Fluke 78 multimeter

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David Jupp:
Fluke does have a calibration/repair facility in UK - though I don't expect it'll be particularly cheap.  I suppose no harm asking them for a quote.

naffsharpe (Nathan):
Hi John and David.
Again my thanks for your continued interest and help. I had intended to post earlier but the weather here in Gwynedd was far to good to stay indoors today.
I bought 2 new PP3 9v Alkaline batteries with the intention of sitting here and carrying out the suggested tests , fitted one and the meter came to life instantly !
I metered the original PP3 and measured 9.1v then removed the new PP3 and measured 9.28v both were metered with my AVO 310 . Surely that 0.18 v difference cannot be the cause of the failure? The 9.1v PP3 had been in the meter for only 3 days .
I'm pleased but find it a bit of a puzzle .
Now it's working I can measure the square wave Hz output on my alternator to see if it is the cause of problem with the VW Dynamic Oil Pressure Monitoring system on my van . This is used to give a speed signal to the system, VW dropped the system in 2002 because of the problems with it and now refuse to talk about it !

Many thanks to you both,  Nathan.

philf:

--- Quote from: naffsharpe (Nathan) on June 30, 2015, 05:34:29 PM ---I metered the original PP3 and measured 9.1v then removed the new PP3 and measured 9.28v both were metered with my AVO 310 . Surely that 0.18 v difference cannot be the cause of the failure? The 9.1v PP3 had been in the meter for only 3 days .

--- End quote ---

Nathan

Have you tried putting some load on the two batteries before measuring the voltage. I have a cheap digital multimeter with 2v and 9v battery test ranges which put a load on the battery. Testing on the normal voltage range and battery test range can be very different.

Phil.

naffsharpe (Nathan):
Phil, I'll try them in an old radio I keep in the workshop tomorrow, too hot to go out there now it's still 21.9 C.

Nathan.

John Swift:
Hi Nathan

yes the weather has been nice here , on a clear day like today I can see north wales

good  to see the meter is  working

it could be as simple as switching on and off several times has cleaned the switch contacts

I've noticed some combinations off battery terminals and battery connector don't make a good connection
either the positive battery terminal is too small a diameter or the inside diameter of positive battery connector
too large

the input resistance of digital multimeter on a DC voltage range is too high to test a battery
 
you should see a more meaningfull  result if you connect a 1K resistor across the 9V
the extra current through the 1K resistor will increase the volt drop across the  batterys internal resistance
which increases as the battery discharges
you may find using your AVO 310 and a 1K resistor the old battery voltage is only 6 or 7 volts

   John

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