Sunday, November 03, 2013

Fluke 39 Power Meters, Battery Corrosion Fun, Part 1

All good things come my way from the OSU Surplus sale these days. Last Wednesday I bought 3 Fluke 39 Power Meters, which Fluke calls “Power Harmonics Testers” and dealers sometimes call “Power Quality Analyzers” or “Power Harmonics Analyzers”. Whatever. They were cheap and I even got most of three sets of leads (they were on a shelf in the section that holds housewares) which is a rare and happy event. I won’t tell you what I paid because you will hate me. The current replacement for this model, the Fluke 43B/003 Power Quality Analyzer, is insanely expensive.
Manuals here.

When I opened up the battery compartments I found out why they were being sold…full of battery corrosion.
This one actually had the batteries. Rather than standard decomposition they seemed to have just gotten really rusty, so much so that metal was horribly eaten.
Regular alkaline crust, but in significantly larger amounts than I’m used to. The meters take 4 C cells. Happily most was contained in the battery compartment cover, which is good. If they had been stored upside down things could have been much worse.
6 screws and some gentle prying with a feeler gage opened the first one up.
The “Spring, Battery” was eaten through.
The terminal is really crusty. Part #BP1. I don’t see reference to it in the service manual beyond it being shown in the schematic. I should call up Fluke and see if I can get replacements.
Some glamour shots.
In order to remove the main board you have to unlatch a ZIF socket from the flat cable.
The amperage BNC connector leads slip out but the voltage wires are soldered to the board.
LCD display board.
Notice the Zebra connector.
Better shots of the BNC leads.
2nd meter has crust on the same terminal…
Third meter is not corroded!
A quick dip in vinegar for the 2nd one’s terminal. The first one I’ll save for later…Not too bad but the plating is stripped off. I ‘m unsure as to whether or not the contact is beryllium copper but I’m generally paranoid so I won’t be cleaning it with abrasive methods.
Vinegar neutralizing the alkaline deposits. Note the rusty one is not bubbling.
All cleaned up, and dried off.
I’ve never seen corrosion eat plastic before. I’ve heard several different theories, that there are additives in the plastic that allowed the corrosion to penetrate, that it released heat that allowed the plastic to decompose, or that it was a thermoplastic that was susceptible to alkaline attack. In any case that’s pretty amazing. The covers were attacked more than the body, which is good.
Power on!
Neat leads.
Well two are working!
Yes, I decided that maximum boredom could be produced by making this a two parter…more to come…Part 2.

No comments: