Old Siemens B1022 RMS Multimeter Repair - Help Needed!

[ionbasa]

So my father just came back from his trip to Romania, and he brought his favorite multimeter back with him. I've never actually seen this type of model before, to make things more interesting: when searching google for the Siemens B1022, nothing similar actually pops up.

If anyone is interested, I have the manual printed in both German and English, I might scan the important pages: schematics, block diagram, and specs.
I have attached some pictures here of the multimeter:










Now, I have a few questions. The meter itself has only been calibrated once in its lifetime, will cal-labs still calibrate this meter? The reason I ask is because my father loves using this meter. Also, it hasn't been powered on in about 19 years as its been basically been sitting collecting dust until my father found it. Are their any precautions I should take? It takes a 9v battery. All connectors on the meter are basically clean.

The only thing its missing is a pair of probes/leads. Anyone have any good recomendations for 10Amp leads?

[Bored@Work]

Now, I have a few questions. The meter itself has only been calibrated once in its lifetime, will cal-labs still calibrate this meter?

Yes, e.g. Gossen-Metrawatt calibrates old Siemens meters. 113 Euro + VAT, and probably some expensive shipping, too. http://www.gmci-service.com/en/general.html

[ionbasa]

Yes, e.g. Gossen-Metrawatt calibrates old Siemens meters. 113 Euro + VAT, and probably some expensive shipping, too. http://www.gmci-service.com/en/general.html

Ouch. Thats expensive. Do you happen to know of anyone in the USA or North America?

[Wytnucls]

Get yourself a cheap voltage reference, power up the meter and see how it does. I wouldn't be surprised if it is still within the 1-year accuracy specs. If it is not, open it up and adjust the appropriate pots on the PCB. I doubt that this meter can only be calibrated through software, but it is possible. That would save you a load of money and postage fears.
Try to upload as much of the manual as you can and if you open it up, take some pics of the PCB.

Model B1023:



Model B1021:



Model B1020:



Model B1008:



Model B1002:

[Wytnucls]

More models in the same Siemens series B1024, B1028 and some similar LEM Norma Goerz DM910-950 (Austria):
DM950 21,000 count True RMS
LEM was acquired by Fluke eventually.

[ionbasa]

Get yourself a cheap voltage reference, power up the meter and see how it does. I wouldn't be surprised if it is still within the 1-year accuracy specs. If it is not, open it up and adjust the appropriate pots on the PCB. I doubt that this meter can only be calibrated through software, but it is possible. That would save you a load of money and postage fears.
Try to upload as much of the manual as you can and if you open it up, take some pics of the PCB.

Ok, I managed to work the outer shell off here are some pictures of the PCB and interesting areas:









I will try and get a scan of the manual tommorow. Its near 9:30PM here in California, need to get some work done and then get some rest for tomorrow.

Also, some interesting behavior I noticed: The meter basically requires almost brand new fresh 9v batteries. All the ones I had laying around the house prompted the  "low battery' and the overflow indicators on the screen. I'm not sure what the overflow indicator is supposed to mean? Does the manual mean "overload" instead of "overflow"? The manual was printed in Austria as well, so maybe along the lines some improper translation happened from the original german portion.

ANother thing I found peculiar was that the manual strictly calls out that the battery should be a 9v Alkali-Manganese , so far from my testing Duracell CopperTops which are Alkaline seem to work just fine.

Regarding calibration, I noticed that there is a terminal block left on the PCB, possibly for calibration equipment? The manual claims that there were optional accessories for IEEE 488, RS 232, Centronics, Analog output, and Commodore c64/sx64/c128 interfaces.

[retiredcaps]

Also, some interesting behavior I noticed: The meter basically requires almost brand new fresh 9v batteries.

On a multimeter that I was trying to fix, I found that my brand new 9V battery died in almost 4 hours.  Then I decided to measure the current draw and was surprised to see the multimeter draw 85mA when I expected around 1mA.

You may want to see what the current draw is?

In addition, carefully check the capacitors for any leakage from the bottom.

[ionbasa]

On a multimeter that I was trying to fix, I found that my brand new 9V battery died in almost 4 hours.  Then I decided to measure the current draw and was surprised to see the multimeter draw 85mA when I expected around 1mA.

You may want to see what the current draw is?

In addition, carefully check the capacitors for any leakage from the bottom.

Good point, I'll see if I can check the current draw tomorrow afternoon. The caps look clean. My father said it may have been to a cal-lab once. There are stickers on the inside which read "geprüft"  which translates to 'tested' in english. The only thing though was that the cal lab didn't mark a date on 2 of the sticker I found. One sticker was in the battery compartment and another on the PCB.

The manual calls out that an alkali-manganese cell should last ~500 hours of operation.  Again, I think there may have been a translation error, and it should infact say alkaline-manganese?

[radhaz]

A very nice looking meter. Definitely scan and post the manual for future users.
Regarding the electrolytic caps, it might be best to just order a bunch of new ones and replace them all, unless you have a reliable capacitor analyzer and a lot of spare time.

[Wytnucls]

The most original probes for this meter would be the Gossen  KS 17

https://www.valuetronics.com/detail/New-gossen-metrawatt-ks-17-one-z110k.cfm

[ionbasa]

Ok, so I'm having some problems with the meter. I bought a fresh pack of batteries and the meter doesn't work as expected.

I ended up taking it apart and cleaning the rotary switch with isopropyl alcohol. But this hasn't helped. If I leave the rotary switch in the ohms/resistance/continuity settings and power it on, the display works, but the meter wont measure any resistance. If I set it to continuity, the meter detects that there is a closed circuit, when there is none.

Setting the rotary switch to Volts, Temp, Amps, or frequency nothing happens. If I switch it on in one of these settings the display comes on for about 1 second and then disappears.

Any thoughts? I also managed to get a AC voltage while playing with the unit. Turning it on and off repeatedly occasionally makes it 'work'. I measured what was supposed to be a 120v AC voltage, but the meter read exactly half the value ~60v.

[Wytnucls]

Upload the schematics and someone may be able to help you.
I would first confirm all circuit voltages are normal then test or replace the old electrolytic caps.
If the battery current draw is higher than 10mA, suspect that something has shorted on the PCB.

[ionbasa]

Upload the schematics and someone may be able to help you.
I would first confirm all circuit voltages are normal then test or replace the old electrolytic caps.
If the battery current draw is higher than 10mA, suspect that something has shorted on the PCB.

Ok, got around to doing it today. I measured the mA. When turning the meter on the initial spike is ~5.0mA to 5.9mA. It then settles near 2.0mA, as soon as that happens the screen starts to fade away.

While I am at it I also scanned the schematic, It doesn't look beautiful in any regards, the original print basically looks exactly like the scan, its has bold but tiny fonts everywhere. The power delivery circuit is in the lower left of the scan. You'll see the 9v battery there, an op amp, 1 capacitor, 3 resistors, and 1 transistor.
The opamp is a tlc271cp, made by TI, the exact model ti749b.

Here is a link to the schematics:

[retiredcaps]

Everyone has different techniques to troubleshooting so what I'm suggesting is my method.

1) The datasheet for the main IC is at

http://pdf1.alldatasheet.com/datasheet-pdf/view/128483/NEC/UPD7514G-12.html

I usually take a cursory glance, which I have not done while writing this, to see how it works in general.

2) I like to take voltage readings.  VDD and VSS are "obvious" choices to me.  Are these readings stable?

I also see in the schematic there are some TP (test points).  I suggest taking voltage measurements and reporting them.

3) It is my understanding, that most lcds work require 3V in order to display something.  When the meter displays something, I'm assuming the voltage at the lcd pins is around 3V and when it fades away, the voltage is well below 3V?

4) The 5mA and 2mA current draw sound reasonable right now.

[ionbasa]

Everyone has different techniques to troubleshooting so what I'm suggesting is my method.

1) The datasheet for the main IC is at

http://pdf1.alldatasheet.com/datasheet-pdf/view/128483/NEC/UPD7514G-12.html

I usually take a cursory glance, which I have not done while writing this, to see how it works in general.

2) I like to take voltage readings.  VDD and VSS are "obvious" choices to me.  Are these readings stable?

I also see in the schematic there are some TP (test points).  I suggest taking voltage measurements and reporting them.

3) It is my understanding, that most lcds work require 3V in order to display something.  When the meter displays something, I'm assuming the voltage at the lcd pins is around 3V and when it fades away, the voltage is well below 3V?

4) The 5mA and 2mA current draw sound reasonable right now.

Should I measure the VDD and VSS at the lcd controller? That is the UDP chip you linked the datasheet to. Part of the problem in doing that is that the chip is actually an SMD, but its mounted underneath the display. The display is glued on with epoxy to some zebra strips. So getting to the chip would require me to basically ruin the screen assembly. I can measure the voltage from the op amp though, as it isn't covered by the display.

As for the check points, I'll try them out later today. There is no printing on the PCB, so Ill have to manually try and find where they are at.

[retiredcaps]

Should I measure the VDD and VSS at the lcd controller?

I would measure VDD in as many places as possible as shown in the schematic just to make sure there are no open pcb traces/tracks, bad capacitors affecting VDD, open resistors, shorted transistors, etc.

[DinBan]

Hi there!
I have same multimeter from SIEMENS B1021 and as most of them, mine is without RS232 interface board.
The question is - anybody know where I can buy internal RS232 board for SIEMENS/NORMA or maybe some one know original brand, part number of this board? At the moment I'm looking for any information about this RS232 board for SIEMENS B102x and NORMAMETER multimeters.
Thank you in advance!

[macboy]

Ok, so I'm having some problems with the meter. I bought a fresh pack of batteries and the meter doesn't work as expected.

I ended up taking it apart and cleaning the rotary switch with isopropyl alcohol. But this hasn't helped. If I leave the rotary switch in the ohms/resistance/continuity settings and power it on, the display works, but the meter wont measure any resistance. If I set it to continuity, the meter detects that there is a closed circuit, when there is none.

Setting the rotary switch to Volts, Temp, Amps, or frequency nothing happens. If I switch it on in one of these settings the display comes on for about 1 second and then disappears.

Any thoughts? I also managed to get a AC voltage while playing with the unit. Turning it on and off repeatedly occasionally makes it 'work'. I measured what was supposed to be a 120v AC voltage, but the meter read exactly half the value ~60v.

Let me see if I understand... you have a meter that you know from other tests does not work correctly. Continuity shows shorted test leads when they are not. Volts shows nothing. ... all signs point to an internal short circuit (maybe a failed input protection device) ... so you decide to stick the leads into a 120 VAC household power socket? 

Stop. Now.