Dr. Thiedig Milli-TO 2, 2 Milliohm to 2 Teraohm Resistance Meter

[popp3r]

Hello All,

Been learning and lurking for a while and finally have something that may be worth sharing with the forum.

I recently picked up this piece of kit at a small auction earlier in the week.  As the subject line says it is a 'MILLI-TO 2 Dr. Thiedig' resistance meter.  Nobody was bidding on it and all of the gear I was trying to win went above my spending level.  I'm just a hobbyist with a passion for test equipment ... pretty sure nobody knows what I'm talking about. 

Anyway, I won the item.  Brought it home and decided to do some research in addition to finding the manual.  Well I can safely say that this must not have been a high volume device or in high demand.  I couldn't find much information on the device other than it was used in a large number of scientific studies and research papers as the device to measure point to point and point to ground resistance measurements.  Right, and there was no manual to be found.

I did happen to see one on ebay with an asking price of US$1250.  Which is substantially more than I paid for it.  Which is good in that regard if I decide to sell it and that asking price is accurate.

The equipment was distributed by Monroe Electronics out of Lyndonville, New York, but you'll notice the device was Made in West Germany by Dr.Thiedig + Co (company still exists, but doesn't look to have archived manuals).   That puts its vintage at prior to 1990.

I've sent Monroe Electronics an email asking if they have a manual in their archives.  If that fails I will send an email, in poorly translated German, to Dr.Thiedig + Co (thiedig.com).

The calibration sticker, already violated, urged me to open'er up.

Odd thing about this device, I opened the top and saw nothing but the bottom of the PCB.  After securing the top-bottom, I then removed the bottom.  To my highly untrained eye, everything looks to be in order and it is surprisingly clean (supposedly it was from a lab environment).

Assuming it is not completely out of whack, is it still an item that can be used and its measurement valid today? As a hobbyist, other than my enjoyment of  telling friends and family I can measure resistances from 2 Milliohm to 2 Teraohm, I don't see it getting much use.

If anybody has information about this device and its practical use I would really like to hear about it.

Thanks!

[coromonadalix]

Very clean indeed, a nice find   lucky you

[coromonadalix]

Ask at   http://www.thiedig.com  some user manuals and specs ? you never know

[Vgkid]

Nice. I remember seeing one on epay, a few years ago. Didn't bid on it, couldn't find any info on it.
The silver can with the black cover appears to be interesting. I wonder what is under the shield up  front.

[popp3r]

I heard back from Monroe Electronics ... US$50.00 for the manual.  I'll send an email to Dr.Thiedig + Co and see if they can do any better.

Regardless, I think a manual and kit should not be parted.  I will get it one way or another.

@Vgkid, I will pop the top on the silver can tonight when I get home and attach some pics.  I'm curious as well.

...

[Cerebus]

After seeing an 2T ohm range on the front I was surprised not to see a whole bunch of teflon standoffs and flying wire construction inside. I wonder how they keep the leakage down?

[Vgkid]

@ popp3r: I look forward to more teardowns.
@ Cerebus: I wonder if it is in this shielded section, attached below. Though I wonder how far you can go with guarded(and floating leads) internal to the meter.

[coromonadalix]

I would put nitrile glove or any protective gloves, just to be sure you dont contaminate something with skin oil / fingers traces residues  etc ...

[Vgkid]

I would put nitrile glove or any protective gloves, just to be sure you dont contaminate something with skin oil / fingers traces residues  etc ...

I agree, and try not to let anything touch the components. If dirty.

[popp3r]

Update on tear down.

The hood on the silver can wouldn't budge, so I didn't force it.

Wearing nitrile gloves (good idea!) I removed the metal shielding covering the Rx High terminals.  Attached are the pictures of what is underneath (apologies for the poor lighting).

Of particular interest is the glass encased resistor? called out in the 2nd pic.

I'll provide specs once the manual is received.  I have not found a single original article or document on this equipment yet.  I thought I had some pretty decent Google-fu!

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[bktemp]

The glass/metal thing is a gas discharge tube, used for overvoltage protection. There should be a voltage rating stamped on the side of the metal end caps.

[Vgkid]

Is is possible for you to take some more pictures of the shielded area? IE: take a picture of the front of the caddock resistors(The white thin ceramic components) and the below(I put it in a square) section.
 They weren't to concerned about cleaning up all of that flux.
Take a picture of the markings on that silver can, we might be able to determine what it is used for .
- sorry if I seem demanding- 

[Neomys Sapiens]

Well known Instrument over here. I mostly saw it in combination with a limit discriminator when used for incoming parts inspection, but it is fully applicable to general lab work. If your representative doesn't answer, I could give them a call to enquire fo a manual.

[popp3r]

Much appreciated @Neomys Sapiens, thank you.  I've yet to hear back, but with the memorial day holiday here in the U.S. I don't expect to hear something until Tues. or Wed. next week.

@Vgkid, not demanding at all.  That is exactly how I quench my thirst for knowledge about things; learn from those that know more than you!

I'll take some close-up pics of the part numbers in better lighting over the weekend.

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[Vgkid]

@Vgkid, not demanding at all.  That is exactly how I quench my thirst for knowledge about things; learn from those that know more than you!
I'll take some close-up pics of the part numbers in better lighting over the weekend.

Thanks.

[Seekonk]

Greetings fellow Dr. Thiedig owner.  I have one of those.  Primary use is in insulation resistance testing.  Low ohms testing just got thrown in. I don't have a manual, doesn't much need one.

[P90]

That's a thing of beauty, nice find!!!

[coromonadalix]

strange to seen an eeprom there ??  i have seen in the past use of an eeprom to generate dc ramps voltages ..

[popp3r]

- Manual update -

A vary generous forum member provided me with a manual!

One minor issue, at least for me, it is in German!  I studied German language in high school and was fortunate to travel to Germany a few times for work  .  But that is clearly not enough to translate a technical manual.

I have a few German colleagues at work that I may lean on to help with this one.

I am still pursuing the English version of the manual and will share it once I can get my hands on it.

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[popp3r]

I forgot to mention - if anyone is interested in the German manual please send me a PM.

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[sgamaITA]

Dear all,
I'm interested in the manual of instrument "Thiedig Milli-TO 2, 2 Milliohm to 2 Teraohm Resistance Meter".
I bought the used instrument some days ago.
Please, may you help me?
Thannks a lot in advance

Giusepppe
g.arcaro@giordano.it