amp/volt meter troubles

[akflyer 1427]

I have the digital amp/volt meter shown below.  The problem is that most of the time when I hit the master it will read 3.4 or maybe 6.2 volts.  When I put a regular volt meter across the terminals it (the second meter) will show 12+ volts as it should.  Sometimes a "timex" tap will make the meter read right sometimes it wont.  Sometimes flipping the switch between amps and volts will make it read right...  Any suggestions other than pull it out and take it to an electronics tech.. I am thinking it has to be a loose or dirty connection in the housing.

Is is possible that I could rig a small powder charge to go off so I dont have to bloddy my knuckles (from tapping the hell out of it) inflight to keep it working?

[kl7jw 1]

Don't know that these ideas will work, but it sounds like grounding problem, either internally or between the case of the instrument and the airframe.  Another possibility is the toggle switch for switching from Amps to Volts.  Give the switch a shot of contact cleaner , or WD-40, right where the handle goes in to it, without power applied, work it back and forth then put the power to it.  You are in in a salt air environment there around Soldotna, and it's a bear on electrical contacts inside switches.  Next thing I'd check is the posts for connecting the wires.  Might be just corrosion on the posts between the wires and posts.  If that's the case, get a bottle of Penetrox, and put it on the posts and wires after cleaning and before assembly.  I use the stuff on ALL electrical connections that I take loose and re-install.  It also works wonders on battery terminals and cables.  Clean the posts and cable ends to shiny metal, allpy a moderate coating, and no more corrosion.  Penetrox just happens to be the brand name I bought.  There are other brands that are just as good but I don't know the names of them.  The stuff is used in house wiring between dissimilar metals in distribution panels and junction boxes to preclude oxygen from the metal-to-metal joint and prevent corrosion and electrolysis.  I use it on my car, aircraft, and ATV battery terminals, as well as when rewiring nearly anything.

John Hart  

[kl7jw 1]

Forgot to add that Penetrox or another brand may be availble at Lowe's, Home Depot or most any electrical supply house.

John Hart

[akflyer 1427]

Thanks John.  I have not flown the plane yet, just in the process of re-building it.  The connections are bright and shiny on the back, but I will pull it out anyway and open the case and see if there is anything obvious in there.  The plane has not flown in 5 or 6 years.. The guy I bought it from could not remember when he wrecked it lol.. I found it under a tarp in Wasilla last year..  One more wing to replaace the rib tails on and she will be good to go.

[kl7jw 1]

It's looking pretty good already from the condition it was in.  If I were a betting man, I'd bt that meter case developed a leak that let moisture into it, whether in vapor or liquid form while it sat under that tarp outside.  Good chance of some type of corrosion in there causing the problem, and it could have ruined the meter.  Look inside.  It could also be a lot easier to repair than we think.

John Hart 

[akflyer 1427]

I just got a reply from the guys at EI instruments..

Leonard-

You have a unit that is quite old.  I would guess that one of the calibration pots has decided it wants to travel to Oregon to be replaced.  We can completely refurbish the gauge for about $65.00 plus shipping.  The turn around time is usually only about 2 days.

Please let me know if I can help further.

Thank you,

Dave Campbell

I think I will just pull it out and send it off and that will leave me more time to work on the wing..  I gotta get off my butt and get this thing in the air.

[kl7jw 1]

I think the guage needs that vacation to the lower 48 if the doctors say so!  Not a bad price to repair it these days.  Sounds cheaper than buying a new meter anyway.

John Hart

[akflyer 1427]

yes it is cheaper... to the tune of about 300 hundred bucks cheaper.... thats a few hours in the air, or two hours folding wings    Sorry Guy had to slip that one in there....