This one has been sitting since the summer- it took a while to get all the rain to evaporate from the inside! When I grabbed the pour fella, it had water up to the mirror.
$1 takes it!
A $1 hamfest multimeter teardown: Micronta 22-201U
2
Tag Archives: dmm
Vintage Keithley 130A teardown
Introduction
The latest addition to our vintage collection is a Keithley 130A handheld DMM from the mid-eighties.Keithley is not well known for its handheld DMMs, or at least I’ve never heard of them. It’s a 3.5 digit 0.25% instrument made in mid 1980s
Keithley 172A DMM in pictures
Another ebay find- a vintage Keithley 172 multimeter. The datecodes on the parts range from 1978 to 1984, placing the final assembly somewhere in mid-1980s. It seems fully functional, but could use a bit of a calibration to regain its past precision.
Vintage DMM- Hioki 3200-50
An ebay find made its way into the lab- an industrial quality DMM from Hioki, made in 1984! The meter has some pretty good specs as shown in this datasheet:
- 3.5 digit (1999 count), 0.5% on DC voltage
- 20uA DC current range with 10nA resolution
- 1G input resistance on 200mV range
- Drop proof to 1 meter
- Dust sealed.
- 500 hours battery life using 2 AA
- Neon indicator of overvoltage Continue reading
Keithley 197 Microvolt DMM in pictures
Today’s quick visual teardown is of an 1984 vintage Keithley 197 microvolt DMM, Despite considerable age, it’s still quite alive and kicking and very useful for measuring low currents and voltages.
-
- Front
-
- Handy short manual on the back
-
- Display driver
-
- Painted transistors- some type of matching indication?
-
- A bit of a bodge?
-
- Guard traces around sensitive circuits
Fading display repair on Fluke 8840A
Today’s repair subject is a Fluke 8840A bench DMM that has some display troubles. It would work normally for a bit and then start fading out. A bit later it would come back and work again. The initial thought was that the display simply had too many run hours and is worn out. In that case a replacement is required and is not a very cheap solution. Continue reading
Sinclair PDM35 multimeter teardown
Another Hamfest find is the Sinclair Radionics PDM 35 digital multimeter. Having grown up with ZX Sinclair Spectrum clone, and reading a lot about Sir Clive Sinclair and his creation I wasn’t about to walk by this. If the look of it is a bit calculator-like, that’s because they actually reused a calculator enclosure! This was a cheap model, selling for 33 pounds in the 70-s and 80s
It's a calcu-err-meter
Fluke 8000A teardown and repair attempt
It’s time to see what the flea market special $5 Fluke 8000A looks like up close
Missing an overlay
Continue reading
2012 Rochester Hamfest
Some random pictures from 2012 Rochester Hamfest. Most of the interesting stuff was in the outdoor flee market as usually:
Hello world!
Welcome to my blog of all things electronic. Let’s start with a family picture of my DMMs.
Left to right: ALDA M-838 DMM circa 1994; Wavetek Meterman 35XP- a handy DMM with a very annoying beep; Fluke 8842A- a high end instrument made in 1994 and still looking brand new inside (I’ll have to do a separate post on that), and finally my shiny new Agilent U1252A. You can never have too many of them- by the time you look at input current and voltage and then on the output currents and voltage, four DMMs seems like a bare minimum.