Fluke 189 with high battery drain

[yan]

Hi, I have a virtually unused 189 that has a permanent 2.7mA drain on the batteries when its switched off.

Ive seen the topics here about battery drain issues with the Fluke 189/289 and it all seems to point to the SuperCap.
I've now changed the 5.5V/0.1F SuperCap to a 5.5V/0.33F and its still got the 2.7mA drain!

Anyone seen this before or any other ideas?
Thanks

[bdunham7]

Is this a 189 or a 189/II?

How long are you testing it for?  It could take a while for the drain to taper off if the supercap isn't charged up.

I think the way to test these during repair is to take the supercap off entirely first, verify that the drain is low, then test your new supercap for leakage, then install it.  Some people just leave them off entirely and live with resetting the date/time after every battery change.

[yan]

Hi, its a 189 I think, thats what it says in the display.
I left it powered off a bench PSU for 30mins while I monitored the current.

Yes might remove it again to chk the current drain.
If its not the supercap do you have any other ideas?
Thanks

[lowimpedance]

One other thing to look at is PCB contamination particularly any prior battery leakage etc. I am assuming the meter works correctly apart from the short battery life.
So clean carefully the areas around the super cap and battery power entry on the PCB.

[bdunham7]

Hi, its a 189 I think, thats what it says in the display.
I left it powered off a bench PSU for 30mins while I monitored the current.

Yes might remove it again to chk the current drain.
If its not the supercap do you have any other ideas?
Thanks

You could try leaving it longer, I'm guessing the supercap charging circuit limits current so the draw might be steady until it is nearly charged.  I tried one here and it draws 220uA turned off (still seems a bit much).  I'll leave it without batteries overnight and see what it does in the morning.  If it's not the supercap, I don't know of any other usual suspects.

[yan]

PCBs are spotless and theres been no battery leakage.
I'll test without the supercap and how that goes.
Thanks

[coromonadalix]

I did run my 189 without supercaps,  if you dont do time related data logging, the supercap is useless

I managed to find a 5v - 0.3 farad supercap for 2.50$ usd / piece  bought 5 of them work great

[bdunham7]

I retested mine after sitting overnight with no batteries.  It draws 16mA spike at first, tapers off to under 1mA in less than 1 minute and then slowly dwindles off to a steady 230uA or so.

[yan]

Hi, After fitting the new supercap I did some more tests and monitored it for 3hrs with and without the supercap fitted and the current drain still just sits at 2.6/2.7mA?
So the supercap seems to make no difference to the current draw.

Is there anything else I could look at?