Solartron A211 - vintage voltmeter by Schlumberger - Page 1
Forum section: electronics / general

author: MetraCollector
author_rank: Regular Contributor
timestamp: January 24, 2012, 06:37:02 pm
content: Hello gentlemenI do not collect only Metra and Tesla equipment, but when it is possible, I buy every single measure device avialableOne day I had a great opportunity to buy some Solartron machine. I didn't hasitateSOLARTRON A211 - SchlumbergerThis beautyfull voltmeter was made by Schlumberger company in 1972 in reference to it’s serial number. I bought it from my friend for a symbolic price to my depositary of history measure devices. He brought it from closed laboratory in his home-city. Further discovering of this one seems to be impossible. It’s a pitty, because there is nearly no reference avialable on the Internet about the company. (I couldn't find)- It is a DC/AC voltmeter in range of 100mV – 1000V.- Range is auto or manual.- Fast or slow integration time.- Remote control is avialable- There are some other holes behind the front panel, probably Resistance measuring according to k? control bulb, but this option is not used in this voltmeter revision.My friend told me that there were some issues about this device. Well, I can expect it, this device is 40 years old. There are some replaced parts on the boards inside. He has some issues about bad contact of the boards to the connectors but he managed to fix it.When I obtained the voltmeter I had an issue with the nixie display. One of the digit was permanently on:I was really excited about the voltmeter, especially what can I find inside. I was suprissed. Only hi-end components and parts compared to its age.This is the suspicious IC. The nixie driver 74141. There was already one replaced on the last digit by MH74141 which was made by Tesla company. Despite the poor quality of many components made in Tesla, these nixie drivers were made in really good quality and there are no known issues about these MHs.However, replacing the IC was pain. Schlumberger company made PCB boards using rivets, no plated through holes ! I was impressed. Well, I cracked the old IC and desoldered remains pin by pin. By the way, notice Mullard nixies. This is exotic for mein Eastern Europe.It works well now !Look at this. No through plating. Rivets. A lot of rivets.But now in order. At first I took the cover off. It is a precious aluminium skelet, but cover plates were a little bit deformed. Perhaps a lot of heavy equipments put on it during laboratory years.The digital section. We can find here range switching board, autorange, oscillator and control board. On the left there is a switched power supplySwitched power supply.Empty motherborad after cleaning. There was a lot of dust.Control logic board.Oscillator board. There is some switch for 50Hz/400Hz. Perhaps an option for 400Hz board voltage (vehicles, aircraft ?). According to integration period synchronization.Voltmeter sometimes freezed, shown wrong digits or +00000 value or sometimes just switched range without control comand. This issue was caused by bad contact between connectors and boards. Solution was a rubber polishing of golden pins.Nothing new or special at all. Traditional 2-stage integration voltmeter.But what quality it is ! This is a shield of floating section.Look at it. All the boards are avialable to tip out, however, this means that board fall of the movable motherboard.A great pain of the device are control buttons, exactly the isostats inside. After 40 years, they sometimes jam or don’t want to fall in. I will not repair them because it is very difficult to unmount them and I would have to desolder them.AC Auxiliary board. This board is optional.Floating power supply. Notice that pink electrolytic cap. This one was replaced.WIMA caps. Early years.(From up to down)Input amplifier with typical shielded unit.Range calibration board.AC/DC converter.The integrator.Reference board.Replaced NPN power transistor. This KU611 was very succesfull product of Tesla. They made it by themself without copying western technology.

author: JorgeCarbajal
author_rank: Contributor
timestamp: January 24, 2012, 07:03:57 pm
content: Thats an awesome unit, thanks for sharing all its internals!

author: Unknown
author_rank: Unknown
timestamp: January 24, 2012, 07:20:02 pm
content: And the digits seem to be in good order with no dark areas. Good job restoring it!

author: tekfan
author_rank: Frequent Contributor
timestamp: January 24, 2012, 07:35:40 pm
content: I can't believe how similar the construction is compared to the Solartron 7075:https://www.eevblog.com/forum/index.php?topic=3013.msg40235#msg40235It doesn't have the rivets instead of the plated PCB holes but a lot of the components look very similar. But still you can't beat the nixie tubes in the A211Do you by any chance know what the 5 pin connector is called that the Solartron multimeters used?

author: MetraCollector
author_rank: Regular Contributor
timestamp: January 24, 2012, 07:49:43 pm
content: Thanks for response, I am glad toThat 7075 looks perfect tooAbout the connector - I have no idea what is the name of it. All in all, I feel helpless that I can't find no information about the A211. Or I am looking for information wrong way ?I have already read your thread about your equipment - they are great ! I like the Datron a lot. I noticed you didn't find a manual for 7075. Few days ago I found some documents for 7061, 7150 and 7081 multimeters. Manuals and User Guides. But nothing for older Solartron machines.

author: tekfan
author_rank: Frequent Contributor
timestamp: January 24, 2012, 07:55:19 pm
content: Yes. It's a shame there's so little documentation available on the older Schlumberger equipment.Just a few days ago I got a manual for the 7075. If you want it just say.

author: Kibi
author_rank: Unknown
timestamp: January 24, 2012, 07:58:04 pm
content: Fantastic job! Thank you very much for sharing.I like the way that they just chopped the end off of the KU611 to make it fit.

author: siliconmix
author_rank: Frequent Contributor
timestamp: January 24, 2012, 08:43:43 pm
content: nice one .thanks for the look.first time i've seen a transistor with tesla written on it .neat

author: cayr7272
author_rank: Newbie
timestamp: June 29, 2012, 10:26:42 pm
content: These are mine... A210, A215, A213 all in perfect condition

author: nev23
author_rank: Newbie
timestamp: April 21, 2017, 09:36:04 am
content: I have just got an A210 in for repair. But no probe. Does anyone have any info on the probe? active or passive?Since the mains transformer has taken up smoking, I'm not going to start anything unless I can find or build a probe, and a manual.

author: cvanc
author_rank: Frequent Contributor
timestamp: April 21, 2017, 12:39:09 pm
content: Thanks for posting! A sexy bit of kit.(watch out for the rivets rusting and causing cold solder joints - I remember some RCA broadcast gear I used to work on had this problem real bad)

author: fcb
author_rank: Super Contributor
timestamp: April 22, 2017, 06:42:57 pm
content: That connector on the front looks like a Lemo 1B - but resolution of the image isn't high enough to be sure.