Black Star 4503 GPIB DMM Firmware Question - Page 1
Forum section: electronics / testgear

author: edpalmer42
author_rank: Super Contributor
timestamp: June 02, 2015, 07:01:17 pm
content: I just picked up a Black Star 4503 DMM. I noticed that the EPROM is labelled "R114-50Hz". Since I live in the land of 60 Hz, is there a "R114-60Hz" firmware version? This unit looks like it was factory-modified for 120 VAC so if a 60 Hz version exists they would have swapped the EPROM, wouldn't they?FYI, I've attached a few pictures.Ed

author: Isad
author_rank: Frequent Contributor
timestamp: June 02, 2015, 07:16:59 pm
content: I doubt the eprom is even gona make any differenc.Have you ever powerd that thing up.

author: dom0
author_rank: Super Contributor
timestamp: June 02, 2015, 07:46:33 pm
content: Quote from: Isad on June 02, 2015, 07:16:59 pmNot necessarily. The ADC is a MAX134 (3.75 digit DMM chip), which is an integrating ADC, thus it can't really reject 50 and 60 Hz at the same time (which some S/D modulators can, but rejecting just one will always give a deeper notch). The MCU can set a control bit to select which one to reject with the MAX134 (see datasheet).

author: edpalmer42
author_rank: Super Contributor
timestamp: June 02, 2015, 09:11:11 pm
content: Quote from: Isad on June 02, 2015, 07:16:59 pmYes, I have. It needs to be recalibrated because the Ni-MH battery died, but even so, the DC voltage and resistance readings are quite good. I've also confirmed that GPIB is working.Your comment sounds rather negative. Any experience with this DMM that you'd care to share?Ed

author: santiniuk
author_rank: Contributor
timestamp: June 02, 2015, 09:13:07 pm
content: Ed,These meters were used in our lab at work. I have the full manual if you need a copy scanned.

author: edpalmer42
author_rank: Super Contributor
timestamp: June 02, 2015, 09:15:58 pm
content: Quote from: santiniuk on June 02, 2015, 09:13:07 pmThanks for the offer, but I found a copy of both the operations manual and service manual online. That's one reason I took a chance on it. The other reason is that it was really cheap!Ed

author: edpalmer42
author_rank: Super Contributor
timestamp: June 03, 2015, 04:09:08 am
content: UpdateTurns out I didn't have to calibrate it after all. It stores 10 copies of each set of calibration constants and somehow knows which ones have become corrupted. As long as one copy of each set is valid, it can correct itself. All you have to do is insert the calibration plug. If you happen to have a device connected to the RS-232 port, it will report which sets are corrupt. In my case, one copy of the 4 VAC set was bad. It corrected it and now it's fine.Of course, to do this test I had to figure out that on the RS-232 connector, CTS and RTS were reversed.Ed

author: Isad
author_rank: Frequent Contributor
timestamp: June 03, 2015, 07:56:51 am
content: Quote from: edpalmer42 on June 02, 2015, 09:11:11 pmI am just giving my thoughts.No i havent had any experience with any type of DMM but idk that a epromcan effect what frequency it works.Sry if the comment sounded negative i dont speak englishevry day so its a bit hard.

author: edpalmer42
author_rank: Super Contributor
timestamp: June 03, 2015, 02:47:48 pm
content: Quote from: Isad on June 03, 2015, 07:56:51 amOkay Isad, that's fine. I'm not sure what they could do in an EPROM, either. That's why I asked. But if there's nothing they could do, why would they label the EPROM as 50 Hz?By the way, your written English is quite good.Ed

author: Isad
author_rank: Frequent Contributor
timestamp: June 03, 2015, 03:01:46 pm
content: Quote from: edpalmer42 on June 03, 2015, 02:47:48 pmThey could be just coding for the company.So that only the company know.Or sombody in the company did the smart assso no one els could know what that means.Do you have any source of 50hz.Dont really know but if it works like that i dont know why you would want to change that.

author: edpalmer42
author_rank: Super Contributor
timestamp: June 03, 2015, 05:08:39 pm
content: Quote from: Isad on June 03, 2015, 03:01:46 pmNow that I've got the calibration error fixed I'll start checking out the operation. Since the AC measurements are performed by a True RMS to DC converter I don't see that 50 Hz vs. 60 Hz would have any effect on that. I'll see if there's any effect on a DC measurement made in the presence of 50 Hz or 60 Hz AC. I see that common mode and normal mode rejection ratios are specified at 50 Hz. I'll have to see if I can measure those and see what happens at 60 Hz.When I get a new piece of equipment I always find new things to learn about.Ed

author: Isad
author_rank: Frequent Contributor
timestamp: June 03, 2015, 06:17:28 pm
content: Now that I've got the calibration error fixed I'll start checking out the operation. Since the AC measurements are performed by a True RMS to DC converter I don't see that 50 Hz vs. 60 Hz would have any effect on that. I'll see if there's any effect on a DC measurement made in the presence of 50 Hz or 60 Hz AC. I see that common mode and normal mode rejection ratios are specified at 50 Hz. I'll have to see if I can measure those and see what happens at 60 Hz.When I get a new piece of equipment I always find new things to learn about.EdKeep me updated about that would like to see if that eprom really has to do somthing with the rejection ratios.Would love to get some sort of dmm but dam there is nothing cheap here.

author: Littlejo44
author_rank: Newbie
timestamp: July 23, 2020, 10:59:24 pm
content: Hi there..I know it's been a long time since you made reference to a Black Star 4503 manual, but do you still have access please?John.. Bristol.. UK

author: edpalmer42
author_rank: Super Contributor
timestamp: July 24, 2020, 01:33:59 am
content: http://w.ko4bb.com/getsimple/index.php?id=manuals&dir=06_Misc_Test_Equipment/BlackStarIncludes both the Operator's Manual and Service Manual.

author: AVGresponding
author_rank: Super Contributor
timestamp: July 24, 2020, 05:22:49 am
content: Quote from: edpalmer42 on July 24, 2020, 01:33:59 amThere numerous differences between the issued manuals and the manufactured meters; many discrepancies between part numbers and component values.The manuals are useful, but double check what you're looking at, always.

author: DinoDubroja
author_rank: Newbie
timestamp: September 05, 2023, 06:07:56 pm
content: Hey, Im a little late to the party but if you are still here would you mind helping me out a bit. So i just repalced NiMh battery and powered it on with calibration key inside. How do i tell it to recall stored calibration constants? What do i have to do? I guess it is necessary to connect RS-232 to do this? Thanks!!

author: edpalmer42
author_rank: Super Contributor
timestamp: September 05, 2023, 07:21:30 pm
content: When you turn it on with the plug inserted, it automatically tries to repair the calibration constants. You don't have to do anything.Since you replaced the battery, you've probably lost everything because the constants are only held in RAM. No battery = no data.Your only option at this point is to work your way through the calibration procedure in the manual.AFAIK, there's no way to backup the constants before a battery swap. That's an unfortunate gap in the meter's design.Actually, the battery backup is a sloppy design to begin with. Since you've already lost the data, now would be a good time to update the circuit. The battery voltage is only 2V4 and there's a diode in series between the battery and the RAM chip. That puts the RAM voltage too close to the minimum value even when the battery is fully charged. Revising that circuit is somewhere on my list of future projects. My plan is to increase the battery voltage to 3V6 and adjust the charging circuit to match.Ed

author: AVGresponding
author_rank: Super Contributor
timestamp: September 05, 2023, 08:43:56 pm
content: At least they are easy to calibrate!I ghetto-fabbed a two cell AAA pack into mine, but I like your idea; would suit a LiFePO4 cell quite well I think. As luck would have it I recently came into possession of a fair number of new (other) 18730s...

author: edpalmer42
author_rank: Super Contributor
timestamp: September 05, 2023, 10:55:49 pm
content: Quote from: AVGresponding on September 05, 2023, 08:43:56 pmSomehow an 18730 LiFePO4 cell as a backup battery seems to be a serious case of overkill. However, I totally support the idea of using what you've got. My plan is to use a Varta Mempac 3V6 110mah battery. I ended up with a tray of them a while back. They're NiMH batteries that are designed for memory backup.I like your AAA pack idea. If you used non-rechargeable Lithium cells, they'd provide about 3 volts and they'd last almost forever - basically the shelf life of the batteries.Ed