Need help on a Prema 6040S DMM! - Page 1
Forum section: electronics / testgear

author: JoeD
author_rank: Contributor
timestamp: January 08, 2014, 05:11:23 pm
content: Does anyone have any experience or even better have a Prema 6040S DMM. I have recently acquired one which is not working and need help understanding whether some empty SRAM and EPROM sockets are only occupied when specific options are fitted or should be occupied for the basic unit to work. I have the manual in German but it's not helpful in this area.RegardsJoed

author: tekfan
author_rank: Frequent Contributor
timestamp: January 22, 2014, 01:28:20 pm
content: About 2 years ago I got a Prema 6040 (not the S model). The multimeter powered up at first but I wanted to disassemble it to see what's inside and in the meantime replace the memory backup battery. I know the meter must be either powered up while doing this or you have to apply a voltage to the SRAM chips while replacing the battery. What I didn't know is that if you unplug the SRAM board from the mainboard the SRAM chips lose their calibration constants. Batteries are hidden behind the memory board but are soldered to the mainboard.After this all that the meter does on power-up is display a plus sign and a decimal point.I've seen a lot of these meters on ebay with exactly this problem. The batteries have probably died and caused the plus and decimal point symptom.As far as I can tell there's no calibration enable switch anywhere on the meter (6040). I don't know if the calibration enable is done via the IEE-488/GPIB socket. As far as I know the 6040S model has a calibration enable switch somewhere on the back panel. Maybe you can confirm this and see where the wires of the switch go to. The boards may be similar for both models.I've seen part of the service manual where it says that you need a special software from Prema to calibrate it. I don't know if calibration via the front panel is also possible because of the missing pages of the manual (and it's in German).Here are pictures of my Prema 6040. Probably from mid 1978. As far as I can tell it has all the options available (DC volts, True RMS AC volts, 4 wire ohms, IEE-488/GPIB). I don't know if the EPROMs are for certain options. First determine which analog cards you have installed then see if the number of lacking cards corresponds to the number of missing EPROMs.Link to pictures:http://s1138.photobucket.com/user/tekscopes/library/Prema%206040?sort=3&page=1If you have the manual I'd be happy to pay you for a copy of it.

author: omega256
author_rank: Newbie
timestamp: January 31, 2014, 06:40:29 pm
content: Have you tried to contact the manufacturer?Prema doesn't build any multimeters any more, but they still repair the old ones.

author: carpelux
author_rank: Regular Contributor
timestamp: January 31, 2014, 09:56:45 pm
content: I recently bought a prema 4001 6 1/2 digit bench multimeter. Googling it didn't give much information, but a mail to prema did give me a user / service manual within one day. First class service!

author: branadic
author_rank: Super Contributor
timestamp: June 24, 2014, 08:57:20 pm
content: I think the following is also interesting for other Prema owners.On monday I had a phone call with the Measurement Instruments Div. of Prema, because I have a Prema 5000 I'd liked to calibrate. Giving the serial number I was told that it was build in 1989 and that it has never returned for calibration. But further more I was told that a free software and hardware update for my device is availabe, that was run on devices later by 1989.Beside calibration and the free updates they will change the Dallas NVRAM for some extra cost as well.So it might be a good idea to call Prema, give them you serial number and find out if there is a free update for your device available as well.

author: branadic
author_rank: Super Contributor
timestamp: June 27, 2014, 07:20:54 pm
content: Got a call from Prema today. I was told that after 25 years most of the ranges were still bang on and the calibration data have never been touched since 1989. This can be seen while booting on the display, an underscore character indicates the original calibration data. My guess is, that they verify the calibration data with the one saved in EPROM. The undersorce character disapears when calibration data have been changed. Prema was suprised by that result. Only 2V range was somewhat out of spec.Some of the caps and a fuse have been replaced, NVRAM with its battery was changed, software was updated and hardware too and the DVM will be adusted and calibrated on Monday. Beauty, good old german quality

author: branadic
author_rank: Super Contributor
timestamp: July 05, 2014, 03:38:39 pm
content: I received my Prema this week and also the calibration protocols. A fuse (100mA) for current measurement was broken and replaced (3A), this is why the device failed on all current ranges during prior to recalibration.On the voltage and resistor ranges the device was bang on with the original 25 years old calibration values and still within the 24h limits. Yes correct, no mistake, within the24h limits. This is pretty amazing.The old software was updated and calibration done but with higher limits.At first glance this was somewhat curious, but after a call with Prema I was told that they changed the allowed limits to one year limits, a change they did over the years. Ahh... okay, got it.However, this gear seems to be pretty stable and Prema did everything right. Sad that they skipped producing DVMs/DMMs.Edit: pink - 1 year limit, red - 24h limit, blue - prior to recalibration, green - calibration

author: doktor pyta
author_rank: Frequent Contributor
timestamp: September 02, 2014, 12:42:11 pm
content: Hi,Few days ago I repaired my Prema 6040S multimeter.I wrote this message to Tekfan but i will copy this below:Few days ago I've bought Prema 6040S with manual and schematic.The batteries were completely removed. I managed to repair this DMM (few tantalum caps+ fuse resistors + bad wirewound resistor in thevoltage reference).The batteries are used only to store last machine states before turning off.The calibration is done using helipots, trimmers so it is basicallyproof to battery discharge.Update: If the buttons on the front panel don't work, try to change the position of switch number 6 on the GPIB section (rear). Switch 6 changes mode of control: local/ remote.Present from me: EPROM content:http://rfscientific.eu/memory-dump-directoryPlus some photos that might help You.

author: tekfan
author_rank: Frequent Contributor
timestamp: September 04, 2014, 10:38:00 pm
content: Quote from: doktor pyta on September 02, 2014, 12:42:11 pmThat's probably the first thing I should have checked. Does the display also freeze when it doesn't get any commands in the remote mode or does it start up in the default settings?The ROM dumps will surely help in troubleshooting this thing. I wonder how likely it is for the EPROMs to fail in these old pieces of test equipment.I'll try to post some useful information, but there's so little time and so many things to do.

author: doktor pyta
author_rank: Frequent Contributor
timestamp: September 11, 2014, 11:47:11 pm
content: Sorry for the delay.I've checked my DMM and the local/remote switch is active only when GPIB cable is connected (almost all the time in my case).However I'd suggest to remove GPIB board while troubleshooting.

author: zaphod_beeblebrox
author_rank: Newbie
timestamp: July 27, 2015, 10:57:59 am
content: Hi everybody. This is my first post to the forum and I will try to contribute some information to the PREMA 6040 (not S) multimeter.I've recently bought one on ebay. It displayed wired (and on every startup different) characters on the display. Keypad wasn't working. The NE555 gave a 4Hz signal to the main processor to do a reset. Removing the 555 didn't help to change anything.I removed all the modules but the µC-Board. No changes. One power path is protected by 10R Resistors (no "fuse resistors" but standard 0.25W carbon resistors), both were burned and showed ~160k. I've replaced them and reinstalled one module after the other. When installing the "Digitalplatine 6040-D-1" the resistors started smoking. I've replaced all the tantals - one had 0.2R/short - with high capacity X7R SMD capacitors.That one that was dead was C7 (10µ 16V) which is buffering the 15V supply of the OpAmp. 15V is way to much for a 16V rated tantal...After that replacement the multimeter started up fine but shows results with apprx. 5% offset. I will now replace all tantals and also the electrolytic caps in the power supply.Best,Matthias

author: Mickle T.
author_rank: Frequent Contributor
timestamp: July 27, 2015, 11:08:37 am
content: Schematic diagrams?

author: zaphod_beeblebrox
author_rank: Newbie
timestamp: July 27, 2015, 02:37:50 pm
content: Hi, PREMA did sent me the schematics within a few hours. I will not share them online due to their copyright. If you need them, email is PREMA Semiconductor GmbH <PREMA@PREMA.com>.Best,Matthias

author: guido
author_rank: Regular Contributor
timestamp: April 09, 2018, 09:55:07 pm
content: I also got a 6040, S version. What i think are the fitted options:02 Resistor measurement03 AC measurement06 GPIB09 MathematicsThe processor PCB has all six 2716s fitted. ROM Dumps attached (also on KO4BB). It seems to be from 1981. Needs a full overhaul, so a future project (one of many)