Naturally, the battery is on the CPU card. What I meant by 'couldn't find the battery' was 'couldn't find the processor card.' It didn't take much manual reading to find it. This one:
Somewhat buried under multiple other modules. The battery is about where the oval is, and can only just be seen with a torch. The board has to come out. All good, there's a clear description of the removal procedure in the manual.
Incidentally, by this time I'd noticed something that may be related to the fault. When I'd cleaned the outsides, there was a small amount of a brown residue on the left side. A splash of something. it came off easily. Now I find some had got in through the vent holes, and dripped down both the case inside, and the mainframe. Very little, but maybe some got onto the CPU card. I can't tell yet. At a guess I'd say soft drink. So probably conductive. We'll see.
But first...
In all my electronics career I've never bothered with 'anti-static stations', wrist straps, conductive mats and so on. I prefer the alternative - just learn simple movement habits that control and dissipate static charges via paths other than through electronics. Always touching metal equipment frames first, or ground points on cards. Keeping some skin touching metal frames at all times when working on gear. If picking up or putting down some static sensitive part, first palm-flat on the surface, to equalize potential (desk surfaces are always slightly static conductive, just from normal dirt, sweat, etc contamination.)
So far as I know, this always worked - I never static blew a component. (Fumbling a charged CRT EHT lead against a deflection PCB in a Tek 7104 scope - that's a different kind of screwup.)
But with this spectrum analyzer, I want to be super cautious. Today I bought an anti-static mat and wrist strap from Jaycar. The only type they had. If I'd bought a real one from the net, I'd have had to wait for it to arrive. This:
As expected, the wrist strap lead end to end is 1 meg ohm. The black ground lead is direct wired from alligator clip to wrist strap sockets, and 1 meg to the mat pop-clip. So that's fine. But what about the mat? It
looks like just a sheet of vinyl, but with a pop-clip in one corner. Hmmm... This is made in China, why not be suspicious?
First check, that I didn't expect to work: Press a metal pad on it about 1cm from the pop-clip. Put 25V DC between the pad and clip. See if a multimeter (Fluke 77) can see any differential voltage between either pads, and points on the sheet between.
A: not a sausage. No detectable conductivity.
I guess it's expected to be
very high impedance, to only move electrons around a little. Expecting a garden variety multimeter to see anything is unreasonable.
OK, so how to give it a fair test?
I have this:
It's a hand held tesla coil thingy. Applies really really high voltage, high frequency excitation to whatever is near the tip. Typically used to find leaks in vacuum glassware, because electrons will find even the tiniest passage. You look for where the glow goes.
Point being, to this thing even many 'non-conductive' objects will pull an arc from the tip. Dry concrete, wood, paper, etc. You can judge how conductive so-called insulators are, by how much the corona discharge is drawn to them. Here it is with concrete.
Let's try this on the 'anti-static mat.' First quick try:
The test platform is a sheet of perspex, spaced up off the ground on cardboard boxes. An adjacent concrete step serves as 'ground'. (No really, for this it's good enough.) It's late dusk, 2 second exposure, camera on tripod.
The mat other end is sitting on the concrete. HV tester tip is about 1cm from the closer mat corner.
Hmm... From my experience with the 'leak tester', that mat is no more conductive than any ordinary plastic.
For a comparison, a bit of wire with its other end point-touching the concrete. Competing in arc length with the 'anti-static mat.' Note that almost
anything will draw the arc a little, even small objects in free space, since the arc is HF AC, and most things have at least a little charge mobility. Even plain vinyl plastic.
All right, I need something that could be considered a fair competition. Let's see how the 'anti-static mat' compares to... bubble wrap. The setup:
And running:
Good heavens. There's no discernible difference. This made in China 'anti-static mat' is no more conductive than bubble wrap. It probably is just a bit of plain vinyl sheet.
That's really funny.
Meanwhile, no anti-static mat.
Great.