Voltmeter Sch-31 - Nixie Russian Voltmeter - Page 1
Forum section: electronics / beginners

author: Rafael
author_rank: Regular Contributor
timestamp: March 25, 2018, 02:18:14 am
content: Hello,Please, someone can give some tips (or instructions) to use this russian voltmeter?From the left to right:MAINS - START - MANUAL - TIME DISPLAY - FILTEROn the selector: WARM UPand then, CALIBRATOR.U ---> V+U*---> V-I and I* appears to be a "Sense" input.My questions are:- Warm UP position, should I leave it warming up for 1 hour like modern precisions DMM?- O1 and O2, are zero1 and zero2?- Calibration with positions, what I need to do?Googling deep:https://vk.com/wall396255313_39Thanks for your help.?-31Spasibo

author: jeroen79
author_rank: Frequent Contributor
timestamp: March 25, 2018, 02:49:12 am
content: Quote from: Rafael on March 25, 2018, 02:18:14 amMy guess would be the inputs for current measurements.

author: Rafael
author_rank: Regular Contributor
timestamp: March 25, 2018, 02:03:13 pm
content: Quote from: jeroen79 on March 25, 2018, 02:49:12 amI will try to see something with a low current...

author: MasterT
author_rank: Frequent Contributor
timestamp: March 25, 2018, 02:34:00 pm
content: Quote from: Rafael on March 25, 2018, 02:18:14 am1. Warm up - 1 hour, there is thermostat. My understanding, temperature 45-50, cooper wire coil as temp sensor, so you can calculate temp in the thermostat know that resistance 10k.2. O1 - input disconnected, shorted to ground, range 10mV. I'd call - set zero.O2 - input connected to 1 MOHm, range 10V. Probably, set full scale.3. Calibration, range 10V, input connected to precise voltage divider, my guess 1-2-3 etc volts.Seems dual slope, nothing fancy.

author: Gyro
author_rank: Super Contributor
timestamp: March 25, 2018, 02:36:37 pm
content: Quote from: jeroen79 on March 25, 2018, 02:49:12 amLooking at how the legs of the resistor symbol are drawn, I think it is likely that they are (also?) used as the current outputs for 4-wire resistance measurement.Nice meter.

author: Rafael
author_rank: Regular Contributor
timestamp: March 25, 2018, 02:49:42 pm
content: Quote from: MasterT on March 25, 2018, 02:34:00 pm1 - Right, I will wait for one hour before do something. Ambient temperature is around 23 celsius. Should I connect a copper wire coil in U and U*?2 - O means Zero? Or some russian word starting with O ?O1 - I tryed yesterday to short U, U*, I and I*, shows a negative number (-0.000120) responsive to the trimpot, but I reach the end (or start) of the trimpot without reach the absolute zero.O2 - Should I put a 1MOhm resistor, one lead to U and I, other lead to U* and I* and try to adjust, right?3 - Can I use a resistor decade?Quote from: Gyro on March 25, 2018, 02:36:37 pmYes, I want to see this device working fine...

author: MasterT
author_rank: Frequent Contributor
timestamp: March 25, 2018, 03:05:25 pm
content: Quote from: Rafael on March 25, 2018, 02:49:42 pm1. Temp sensor is Inside a thermostat, you should not do anything except switch to right position. Indication should get stabilized when temp reach equilibrium.2. No words, zero sign most likely meaningIf you can't adjust to 0 exact, than device must be re-calibrated or repaired.1 MOHM - is internal.3. Divider also is internal, what indicator shows when you rotate a dial?

author: Canis Dirus Leidy
author_rank: Regular Contributor
timestamp: March 25, 2018, 03:10:27 pm
content: Quote from: Rafael on March 25, 2018, 02:18:14 amIt's input for current measuring.Quote from: Rafael on March 25, 2018, 02:18:14 amYes (In normal mode. After repair and parts change it's became more complicated: repair manual (those 200MB pdf file) describes two very long running-in cycles at different environment temperatures).Quote from: Rafael on March 25, 2018, 02:18:14 amYes, they are for device zeroes adjustment. O1 - voltage zero, O2 - current zero.Quote from: Rafael on March 25, 2018, 02:18:14 amIf I correctly understand repair manual it's for use with standard cell (or equivalent voltage source) connected to "Em" sockets on rear panel. "1-10" switch change scaling amplifier gain. Unfortunately, the complete calibration procedure described in "Technical Description" and this document is not available in the Internet.

author: Rafael
author_rank: Regular Contributor
timestamp: March 25, 2018, 03:42:18 pm
content: Warm UPDisplays are running.Just power on.

author: Rafael
author_rank: Regular Contributor
timestamp: March 25, 2018, 03:46:38 pm
content: O2 - Current Zero.O1 - Voltage Zero.Display running...What I need to do to adjust to zero?I can´t send to repair or calibration...I get the impression I saw all the digits lit up yesterday.

author: Rafael
author_rank: Regular Contributor
timestamp: March 25, 2018, 03:56:24 pm
content: Calibration.Just numbers running, no matter if 1 or 10 position.

author: Rafael
author_rank: Regular Contributor
timestamp: March 25, 2018, 04:29:55 pm
content: - H.3. +Normal Element...Calibration input?Seems to be a voltage input.

author: Canis Dirus Leidy
author_rank: Regular Contributor
timestamp: March 25, 2018, 04:46:22 pm
content: Quote from: Rafael on March 25, 2018, 03:46:38 pmSwitch the device to the corresponding mode and adjust potentiometer (slotted screws on front panel). Warning: these settings are interdependent, so the zero setting for each mode will have to be repeated several times.Quote from: Rafael on March 25, 2018, 03:56:24 pmWell, if calibration input has remained unconnected then device "measure" some noise on amplifier output.Quote from: Rafael on March 25, 2018, 04:29:55 pmThis. Try to connect some DC voltage source (and set gain value so that the resulting voltage was no more than 10V) and see if there any sane result.

author: Rafael
author_rank: Regular Contributor
timestamp: March 25, 2018, 04:59:37 pm
content: Quote from: Canis Dirus Leidy on March 25, 2018, 04:46:22 pmRight, but I need to short U, U*, I and I* or all front panel inputs? GND, U, U*, I, I* and 1Kv?When you say: "repeated several times", what I think:Find zero in position O1 and O1 using potentiometers, then, put the switch to, for example, 10V and find again. Or each time that I turn on the voltmeter?Quote from: Canis Dirus Leidy on March 25, 2018, 04:46:22 pmIt seems clear, I will try to do this.Thanks for the explanation and patience.

author: Canis Dirus Leidy
author_rank: Regular Contributor
timestamp: March 25, 2018, 05:45:52 pm
content: Quote from: Rafael on March 25, 2018, 04:59:37 pmIf you switch to O1/O2 mode then all the necessary commutations (plus bypassing amplifier) are done automatically.Quote from: Rafael on March 25, 2018, 04:59:37 pmI meant that adjusting zero in one mode disturb adjustment made in other mode. So zero setting algorithm look like this:Switch to O1 mode. Adjust zero.Switch to O2 mode. Adjust zero.Switch back to O1 and repeat until setting up zeroes in both modes

author: Rafael
author_rank: Regular Contributor
timestamp: March 25, 2018, 06:20:39 pm
content: Quote from: Canis Dirus Leidy on March 25, 2018, 05:45:52 pmLooks an amazing device.If I don't need to short inputs, I need to do another adjustment to reach zero? I mean, on the top of the device, there are potentiometers, untouched potentiometers, I need to do some adjustment?Thanks

author: Canis Dirus Leidy
author_rank: Regular Contributor
timestamp: March 25, 2018, 08:35:59 pm
content: Quote from: Rafael on March 25, 2018, 06:20:39 pmIn the norm - no. These trimmers are intended for assembly (Device was designed in seventies. What is mean discrete components and a lot of manual adjustment) and service technicians.

author: Rafael
author_rank: Regular Contributor
timestamp: March 25, 2018, 10:40:33 pm
content: Well.According to the instructions, I was able to better understand how this excellent machine works.1 - The selector must be in the "warm up" position. A negative number will start to run fast (-00.83000) and then, around one hour, this incremental number will run slow, very slow (-00.94000) until you see this "race" becomes very slow, giving the impression of not running anymore. I understand that the device is ready!2 - In O2 position, it´s possible to adjust the potentiometer until you see (+000000) alternating with (-000000), for me, the voltage zero is done.3 - In O1 position, it´s not easy to set the zero, but something near of it, by the speed of variation between (+000065) and (-000050).4 - Checking again O2, need a small adjustment again.5 - Checking again O1, another small adjustement back to 4 until you a balance between the two settings. At this point, nothing is connected to the inputs.6 - Calibration position, I started with a voltage of 2.5V and saw in the display: (+1.020000), so I turned the dial from 1 to 10, nothing changed. I understood that for this calibration, it is necessary, through the back connectors, the voltage of 1.0V.7 - I put 1V and I understood that the selector was just a fine adjustment, for example: If the selector is in position 5, adjust the potentiomentro to exact 1.000000v, in position 6 it will be 1000100v, in position 7 will be 1,000200ve in position 4 will be 0.000900v. It is as if the selector was a fine adjunct, some actuation of the amplifier to hit the input voltage.I have two challenges ahead: I need to make a connector with probe cables, I thought of making a board that fit perfectly in the connectors and with a selector switch for 1kV and another to connect U with I and U * with I *. The other challenge is to make a stable reference of 1.000000v.Attached, some images.Spasibo!!

author: Rafael
author_rank: Regular Contributor
timestamp: March 25, 2018, 10:41:51 pm
content: More images...

author: Rafael
author_rank: Regular Contributor
timestamp: March 25, 2018, 10:46:15 pm
content: Thanks!