Author Topic: EEVblog #613 - Prema 6047 Multimeter Teardown  (Read 19247 times)

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Offline EEVblog

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EEVblog #613 - Prema 6047 Multimeter Teardown
« on: May 06, 2014, 11:19:49 pm »
Teardown Tuesday.
What's inside a 1980's vintage 8.5 digit multimeter, the 6047 from Prema. Or did Dave diddle himself?
Hi Res photos: http://www.eevblog.com/2014/05/07/eevblog-613-prema-6047-multimeter-teardown/

« Last Edit: May 06, 2014, 11:27:39 pm by EEVblog »
 

Offline quarks

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Re: EEVblog #613 - Prema 6047 Multimeter Teardown
« Reply #1 on: May 06, 2014, 11:46:08 pm »
 Nice score, but not 8.5 digit
See the real ones here
https://www.eevblog.com/forum/testgear/8-5-digit-dmm/msg258880/#msg258880
« Last Edit: May 07, 2014, 12:16:37 am by quarks »
 

Offline FrankBuss

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Re: EEVblog #613 - Prema 6047 Multimeter Teardown
« Reply #2 on: May 07, 2014, 12:08:29 am »
Reading the EPROM would be interesting. Sometimes there are hidden messages or easter eggs: http://www.lemon64.com/forum/viewtopic.php?t=49609
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Offline gaijin

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Re: EEVblog #613 - Prema 6047 Multimeter Teardown
« Reply #3 on: May 07, 2014, 01:11:00 am »
The 100 milliohm shunt resistor was made by ISOTEK they have been around since 1989.

http://www.isotekcorp.com/
 

Offline senso

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Re: EEVblog #613 - Prema 6047 Multimeter Teardown
« Reply #4 on: May 07, 2014, 01:17:37 am »
That thing looks like it was used in the shop floor so all the new assemblers could try and melt some FR4, that or it was repaired by someone else, but it really doesn't seem to have the spit and polish of a precision bit of kit, more like a 6 month special kit from elektor  :-DD
 

Online Vgkid

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Re: EEVblog #613 - Prema 6047 Multimeter Teardown
« Reply #5 on: May 07, 2014, 01:37:50 am »
That is a beautiful meter, and it arrived in good condition as well. Here is the manual W/ schematics
http://www.ko4bb.com/manuals/index.php?dir=09)_Misc_Test_Equipment/Prema
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Offline david77

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Re: EEVblog #613 - Prema 6047 Multimeter Teardown
« Reply #6 on: May 07, 2014, 02:09:40 am »
Nice score Dave!

Love the SDS brand relays in there. That company used to be in my hometown, the factory is still there now owned by Matsushita/Panasonic. They're still making relays and industrial control gear there.

Btw. Isabellenütte is rather older than 25 years...
http://www.isabellenhuette.de/en/company/innovation-by-tradition/history/
« Last Edit: May 07, 2014, 02:31:37 am by david77 »
 

Offline justanothercanuck

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Re: EEVblog #613 - Prema 6047 Multimeter Teardown
« Reply #7 on: May 07, 2014, 03:28:49 am »
Did you say 6502?  ;D

I wonder what the ROM looks like.  Is there a ROM dump out there?
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Offline TiN

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Re: EEVblog #613 - Prema 6047 Multimeter Teardown
« Reply #8 on: May 07, 2014, 04:24:00 am »
Lovely, volt-nuts will enjoy. Thanks for teardown.
Moar precision DMM content, please   :-DMM

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Offline SeanB

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Re: EEVblog #613 - Prema 6047 Multimeter Teardown
« Reply #9 on: May 07, 2014, 05:20:24 am »
Nice score Dave!

Love the SDS brand relays in there. That company used to be in my hometown, the factory is still there now owned by Matsushita/Panasonic. They're still making relays and industrial control gear there.

Btw. Isabellenütte is rather older than 25 years...
http://www.isabellenhuette.de/en/company/innovation-by-tradition/history/

Funny enough I had a faulty thermal resistor from them, had to replace it with an Omron H3B timer. 11 pin timer block, 11 pin base, mount on DIN rail and wire it up, all to replace a single 2 wire part. The Isabellenhutte thermistor was taking too long to heat up, and the part number ( thanks to Google translate) is now obsolete 40 years.
 

Offline Stonent

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Re: EEVblog #613 - Prema 6047 Multimeter Teardown
« Reply #10 on: May 07, 2014, 06:00:32 am »
I was surprised he didn't point out the HP chips on there. I didn't catch what they were, though.
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Offline Huluvu

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Re: EEVblog #613 - Prema 6047 Multimeter Teardown
« Reply #11 on: May 07, 2014, 06:20:04 am »
Yeah -  FRAKO Electrolytic Capacitor around 18:10  :-+

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Offline Mickle T.

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Re: EEVblog #613 - Prema 6047 Multimeter Teardown
« Reply #12 on: May 07, 2014, 06:27:13 am »
Can't find a datasheet for HP R8200 optocoupler  :(
 

Offline Rasz

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Re: EEVblog #613 - Prema 6047 Multimeter Teardown
« Reply #13 on: May 07, 2014, 07:39:18 am »
I bet the 6048 is just one bit flip in dallas ram :)
6502 is trivial to reverse engineer
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Offline poorchava

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Re: EEVblog #613 - Prema 6047 Multimeter Teardown
« Reply #14 on: May 07, 2014, 08:05:37 am »
Isabellenhütte produce shunt resistors and power resistors (up to several hundred watt) and roll their own resistive alloys. Great quality and stability too. I've seen some automotive qualification results (pretty stringent standards) and their standard range of products exceeded the pass criteria literally by orders of magnitude. Really good stuff :-+
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Offline sportq

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Re: EEVblog #613 - Prema 6047 Multimeter Teardown
« Reply #15 on: May 07, 2014, 08:27:23 am »

Although it was labelled as serial number 1040-something, I bet they started at 1000. HP did this, nobody wants serial number 0001 (except eevblog uC fans :) )

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Offline wiss

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Re: EEVblog #613 - Prema 6047 Multimeter Teardown
« Reply #16 on: May 07, 2014, 10:04:06 am »
I bet the 6048 is just one bit flip in dallas ram :)
6502 is trivial to reverse engineer

Almost, substitute lm399 for ltz1000.
But same input-amp.
 

Offline opablo

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Re: EEVblog #613 - Prema 6047 Multimeter Teardown
« Reply #17 on: May 07, 2014, 12:33:33 pm »
What's so special about Tellurium Copper ?

I just read the wikipedia article on Tellurium and didn't got what's so special about it for electronic connectors...
 

Offline robrenz

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Re: EEVblog #613 - Prema 6047 Multimeter Teardown
« Reply #18 on: May 07, 2014, 12:46:36 pm »
IMO it is purely for the machinability ONLY.  It does nothing for electrical properties and is not as good as oxygen free copper electrically. If it was better electrically you would see it in spade lugs etc. but you don't. You will only see it used where the product is machined (turned milled etc.) not stamped like spade lugs. Telurium copper is readily available only in round stock further supporting my theory that it is purely for machinability.

Offline Zbig

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Re: EEVblog #613 - Prema 6047 Multimeter Teardown
« Reply #19 on: May 07, 2014, 09:39:20 pm »
Koax!
 

Offline Dr. Frank

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Re: EEVblog #613 - Prema 6047 Multimeter Teardown
« Reply #20 on: May 07, 2014, 09:42:48 pm »
Isabellenhütte produces very good low ohm shunt and power resistors.
See here: http://www.isabellenhuette.de/en/home/

I think the designation "Hütte" originates from the metallurgical "smelting" process. (I hope I have picked the correct English term.)
Obviously that's the historical root of this company.

In the famous old Ruhrgebiet, in Western Germany (Krupp, Thyssen, Mannesmann, etc.) they smelted the ordinary steel and iron alloys, but this company specialized in electrical alloys, obviously. Today, they still produce their own specialty alloys.

The brand "Zeranin" is a special or selected Manganin alloy, T.C. being <3ppm/K, or even <1ppm/K, instead of >= 10ppm/K for the elder Manganin.
High quality wire wound precision resistors are also made of Zeranin, and fully compete against the metal foil technology of Vishay.


What I have noticed, all PCBs were labelled 6048, therefore, probably a different assembly and a different EPROM may turn this instrument into a real volt-nuts 8 1/2 digits one.

Around the LM299, there's enough space for the LTZ1000 and its accompanying components.

But anyhow, if calibrated properly, even this version is capable of ~1ppm stability, especially after 25 years of ageing.
Therefore this instrument will definitely qualify Dave as a real volt-nuts.


Frank

(who initially created the term "voltnut")
« Last Edit: May 07, 2014, 09:54:00 pm by Dr. Frank »
 

Offline guido

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Re: EEVblog #613 - Prema 6047 Multimeter Teardown
« Reply #21 on: May 07, 2014, 10:53:54 pm »
That blue philips cap is not original i think.

I have a prema 5000 (5 euro  :-+), which has similar parts like the relays and reference. But more prema specific ic's, it is a lot more integrated and smaller. But 6.5 digit only. Those board to board connectors are horrible. Mine has only one towards the display pcb and it took some tinkering to get it reliable. But in the 5000 the other board to board connectors are flatcables with connectors pressed into regular ic sockets  :palm:   Did a full recap on mine, i use it a lot these days. Got it 'calibrated' at a real voltnut ;)

The analog board:


Interestingly the 6502 clock is derived from the analog side (adc) and transported to the dig side with an opto. In your meter it is "free running".

Prema is very helpful if you mail them! They still support their meters. E.g. full calibration for your meter is 653 euro according to a pricelist i got last year. Calibration can probably be done via keys and gpib. They also still repair them, so i guess they have some of those prema chips available. They are also willing to answer technical questions via mail and send service manuals.

My guess is that the battery is flat. In the 5000 are three 2114 rams. One is battery backupped and its a cmos version where the others are not (everyone that had an Acorn Atom in the past knows how power hungry the regular versions are :))
« Last Edit: May 07, 2014, 11:14:42 pm by guido »
 

Offline rolycat

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Re: EEVblog #613 - Prema 6047 Multimeter Teardown
« Reply #22 on: May 07, 2014, 10:56:57 pm »
IMO it is purely for the machinability ONLY.  It does nothing for electrical properties and is not as good as oxygen free copper electrically. If it was better electrically you would see it in spade lugs etc. but you don't. You will only see it used where the product is machined (turned milled etc.) not stamped like spade lugs. Telurium copper is readily available only in round stock further supporting my theory that it is purely for machinability.

I'm not sure it's the only reason - tellurium copper combines low thermal EMF with better corrosion resistance than pure copper.
 

Offline robrenz

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Re: EEVblog #613 - Prema 6047 Multimeter Teardown
« Reply #23 on: May 08, 2014, 01:49:17 am »
Show me a couple of NON machined mass produced electrical components made of Tellurium copper and I might alter my opinion ;D

Offline Wytnucls

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Re: EEVblog #613 - Prema 6047 Multimeter Teardown
« Reply #24 on: May 08, 2014, 02:58:13 am »
The Tellurium Copper machinist never runs out of elbow room  ;)


 


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