On we go with the Solartron week.
Today's episode is titled "
The strange case of the 7061". Of course there'll be lots of biggish but useless pictures and some daft commentary.
Summary: This instrument is a weird mixture of 'wonderful' and 'terrible'.
Let us start with the case: plastic with a little bit of metal at the back. While it helps making the instrument rather lightweight (especially for a 19″ case), it looks a bit cheap for something of this class. However, this is not of the kind that shatters by just looking at it. Really sturdy and no isolation problems. Even the rack mount flanges are plastic -
those I wouldn't trust any more after they've seen several years of sunlight. As a 'systems voltmeter', this is meant to be used as part of something bigger, like an automated calibration station in a production line. Here, the expensive input connector makes perfect sense (4 mm plugs and jacks aren't really
that good), and another hundred bucks don't care. The tilted front however seems to be aimed for workbenches. And the sensor keys ... oh dear. Personally, I want tactile feedback. But I have to admit they work flawlessly so far.
My 7061 is equipped with the scanner option. Here, the designers decided to use a different kind of connector for the inputs! Were they just nuts or is the other one simply too big to fit 8 of them within the available space?
Needless to say, I don't have a matching plug.
Enough with the appearances, let's put it on the bench and power up:
It shows no error, good. And stays at this. No measurement. Of course I should have read the manual, but who reads them anyway? Manuals are for wimps.
And all my computers are off, I'm to lazy to boot one, so it's trial and error time.
Easy enough, tapping "TRACK" apparently gets it going.
First it has to measure my 10.00000 V reference:
Yuck, that sucks! (An error of 0.3 % would have been excellent for a meter with movement; I remember seeing a class 0.5 instrument in a catalog 40 years ago. Never could have dreamed that one day I might own meters with that accuracy.) It indeed does measure a voltage in the vicinity of the actual value. This was confirmed with some other voltages. All of them showed a little low (at least the conversion seems to be linear). Should be adjustable.
The display is somewhat strange, with the raised decimal point and the gap. But this actually isn't such a bad idea. E.g., with the HP34401 I keep having problems interpreting the display, as the decimal point is very small, especially compared to the thousands separator. Every now and then I need to look twice. Here it's clear.
The 2 quick tests I do are the already mentioned DC volts (just 2.5, 5.0, 7.5 and 10.0 volts) and my resistance box (0, 1, 10, 50, 100, 1000, 10 k, 17 k, 100 k, 1000 k, 10 M Ohms). The only cable I have has only 2 banana plugs, so no 4-wire measurement.
This is with 1 Ω:
The same silly 'every resistance is kΩ' as with the 7150s. Seems to be a Solartron thing.
And yet, despite only 2 wires, the value isn't too bad. And the resolution implies that the range is
not kΩ, just the display. The switch on my resistance box has 2 open positions. While I went over these, I din't see any 'OPEN', 'OVER' or any such. Hm. Going up to 10 MΩ the measurements took longer. Amazingly, this DMM was the first that gave me a quite stable reading for this! All others have severe trouble above 1 MΩ. Then I got daring and tried a 330 MΩ resistor. After several seconds, I got this:
Holy shitballs! It's not only measuring these high resistances, it is also giving good results! And I was wrong! kΩ is
not the only resistance reading for Solartron (my apologies to them). I'm
really impressed and know now which instrument to use for resistances, especially for those above 1 MΩ.
Now for the ubiquitous nudity.
View from above:
The construction strikes me as exceptionally tidy. No wires running across, no patchwork, all cables neatly arranged. This is the second Solartron instrument that looks much better nude than dressed (that's rare with people, too). It is a real beauty inside, IMO.
My curiosity has killed some devices, but I certainly want to see what's inside the shield. 2 screws can't keep me away:
It's the GLUG oscillator, 49.152 MHz without a crystal. (And don't ask me what 'GLUG' stands for - I haven't found the definition yet.)
A rechargeable NiCd battery (dead). No idea what it is used for. The maintenance manual describes how to remove it (yup, not 'replace'). It's not for the calibration data, they're in a EEPROM.
The scanner, also known as relay cemetery:
For completeness sake, a view from below. Yes, with the basic device everything is easily accessible with just the removing the top and bottom covers. Gotta love it.
Looks like I should invest some time in this. Read the manuals. (Try to) calibrate it. Check the caps. Clean it up (the plastic case has a slightly rough surface; stickers do not really stick there - one more point on the plus side).
On a side note: This post took me 90 minutes to write. I'm really slow. (And despite proofreading three times, there will still be errors. Sigh.)