Test Equipment Anonymous

Here's another DMM that I'd been curious about for quite some time. It has plenty of features but fairly basic performance.



This had two major faults, the NiCd battery had failed and leaked and the power switch is very reluctant to switch on without a lot of alarming arcing.

I quickly removed VARTA, destroyer of worlds, replaced with two NiMH AA cells in a holder, though I might change this to AAA when I get a replacement battery holder. The PCB needed some cleaning but the leakage wasn't as bad as I've seen in other equipment. I changed C21, a 560pF capacitor and adjusted the parallel trimmer to accommodate the slightly different value of my replacement part.

I've left the switch for now but I need to remember not to turn it off, too.

I fed it a pile of resistors, then some outputs from my bench supply and HP 3325A+HV option, measured using the HP 3456A for reference. I didn't succeed in the current calibration, it kept saying BAD, but it wasn't far off, everything else worked.

It's not a bad meter but the AC ranges take several seconds to settle and that's a bit annoying. I think it's doing software averaging. I really like the big LED display and assuming it's reliable it might even become my daily driver on the bench (the Fluke 45 is becoming cantankerous and its VFD is fading).

Another bad point is disassembly, which was horrible due to having to remove hard-to reach plastic and metal nuts, but I'll forgive it that if it continues to work for a few weeks.

DC Current calibration is now complete, it really, really needed the screening metal to be in place.

Excellent; another aged meter brought back to life. And it looks like its display goes to 3.9999, making it quite reasonable accuracy. Useful.

You guys are making me look bad. I gotta find some decent TE to work on. Been very lean here lately.

EC8010 wrote: ↑Wed Apr 22, 2026 6:36 pm Excellent; another aged meter brought back to life. And it looks like its display goes to 3.9999, making it quite reasonable accuracy. Useful.

Yes, it's a 40,999 count design which makes it fine as a basic bench meter. Apparently there's an earlier 4503 that is 20,999, which must be a bit confusing.

I've decided against replacing my Fluke 45 with it, because the BlackStar doesn't have a frequency counter and I use that feature quite regularly (fed with the sync output on my 3312A).

It has 10MΩ input impedance on voltage ranges, though, which is a bit disappointing. The DC accuracy is a fairly poor ±0.03% reading ±0.01% full scale.

AVGresponding wrote: ↑Wed Apr 22, 2026 5:07 pm They're a decent meter. The SRAM battery is very problematic though; I'm contemplating binning off rechargeables on mine (I did do a 2x AAA mod but prolonged lack of use results in cal loss) in favour of hot-swappable lithiums of some sort.


EDIT: Oh, btw, if yours has the GPIB, TheHWcave is looking for a ROM dump (I don't have the means).

I do have GPIB on mine, it seems to work and I've figured out most of the commands though I'm waiting for KO4BB to start working again so I can download the full user manual - I have a service manual but it doesn't have the full list of commands in it. KO4BB also has firmware and I think it's a newer version than I have, but again, not currently accessible. When I change the power switch, maybe this weekend, I'll read the ROM and put it on my website. It has a Hitachi 6303x CPU, which is an enhanced clone of a 6800 with some peripherals, seems quite good and I'm tempted to try to add features…

Here's a link to a permatemporary web page with a link to my extracted firmware. https://mossyvale.co.uk/te/

KO4BB was working recently and I've downloaded the firmware and operating manual now.

The meter is a really useful one and is one of my favourites. When I got mine, it was way out of spec on all ranges as the VARTA had leaked and the resultant flood of electrolyte had reached the extremely high impedance front end and it took many attempts at cleaning the board, but I'm glad I did.

The calibration was a bit of a pig to do, but with perseverance and adaptation, I managed to get it reading close to my +/- 1 or 2 mv (at the time) new Bryman BM867s and my Flukes, which all agreed with my calibrators.