Scored a Datron 1062 for $62, no current mode? - Page 1
Forum section: electronics / general

author: Photon939
author_rank: Regular Contributor
timestamp: February 08, 2017, 06:14:38 am
content: It seems I got lucky with an ebay auction and won a supposedly failed Datron 1062 for $62 (auction stated it failed the self-test with error 6) This is my first 6.5 digit DMM, the others are mostly cheapos.The tag on the back of the unit states it has option 10, 20, 30 (AC TRMS, 4 wire ohms, DC/AC current converter)Running the self test gives me PASS with V omega and an AC indicator icons on the display.I do not have any other equipment to verify its calibration down to 6.5 digits but all readings so far have been good and in line with my other meters.Pressing the button for current results in no response and since it does not appear to be testing current mode in the self test it seems the cpu is not detecting the current board? Looking at the manuals I found online the board in my unit does not match the layout of the current pcb in the manual. I did try re-seating the ribbon cable to no effect.Am I missing something stupidly obvious? To me the manual reads like you can't have option 30 without option 10, so I should have current.Service Manual:https://archive.org/details/datron_Datron_1061_1061a_1062_Service_Manual_complete_with_schematics_and_partlistUser Manual:http://exodus.poly.edu/~kurt/manuals/manuals/Other/DATRON%201061A,1061,1071%20User.pdfThanks

author: Photon939
author_rank: Regular Contributor
timestamp: February 08, 2017, 06:19:26 am
content: Additional photos, note the board is not the same as shown in the manual

author: Gyro
author_rank: Super Contributor
timestamp: February 08, 2017, 11:24:37 am
content: I don't see a current measurement option board in there. The option 30 current mode also needs AC RMS option 10 to be fitted. I doesn't mean that if Option 10 is there, then option 30 must also be fitted.If it helps, Datron only introduce Current measurement opions fairly late. I think their philosophy was that internal current measurement was a bit of a waste of tlime on a precision meter due to voltage burden of internal shunts, overload protection and leads, so you would normally use an external shunt anyway.P.S. You still got a bargain!

author: dacman
author_rank: Frequent Contributor
timestamp: February 09, 2017, 02:50:35 am
content: In the second to last photo, the PCB to the left is Ohms, the middle is ACV, and the empty space to the right is where the current PCB goes. If it did not come with the current option then there should be a 12 pin socket plugged into the pins on the bulkhead with pin 1 jumpered to pin 3 and pin 10 jumpered to pin 12. If it isn't there, I'd ask the seller to send the current option PCB.

author: Photon939
author_rank: Regular Contributor
timestamp: February 09, 2017, 03:46:55 am
content: gyro - Thanks for the info, I was just hoping it would have current mode since the back of the unit says it should have option 30.dacman - the jumper you mentioned is installed, so it looks like either it never had the current board or it was removed and the jumper was installed.I guess the next task will be to replace the electrolytics. Thankfully they do not seem to be heavily used. I count the following:Display board:C18 10uf 250v axialPower supply board:C13 1000uf 40v axialC15 1000uf 40v axialC6 10uf 350v axialC7 4700uf 16v axialMain DC board:C45 47uf 25v axialC46 47uf 25v axialC47 33uf 40v axialC48 33uf 40v axialC49 10uf 63v axialC50 10uf 63v axial11 aluminum electrolytics in the whole thing. Made in West Germany. Neat

author: bitseeker
author_rank: Super Contributor
timestamp: February 09, 2017, 04:37:16 am
content: Nice score! Gotta love those big Panaplex digits.

author: Gyro
author_rank: Super Contributor
timestamp: February 09, 2017, 10:01:39 am
content: Quote from: Photon939 on February 09, 2017, 03:46:55 amYes, a bit of a shame. Mind you, I guess quite a few of us have had bits removed since we left the factory.You could always have a go at building one of course, It's the simplest option board in there.QuoteYou might want to check them first - those Wima electrolytics are very long lasting, I have Datrons from the '70s where the ESR is still superior to new ones. The small Philips ones on the DC board bootstrap supplies might be worth lifting a leg and checking though. At least being axial there's no chance of them eating copper without you seeing, and lead forming radial ones to fit is messy.

author: Photon939
author_rank: Regular Contributor
timestamp: February 10, 2017, 09:32:51 pm
content: I actually like the idea of building a current board, know of any good sources for low tempco resistors and low emf reed relays? I'll start putting a BOM and schematic together.Looking at Mouser/Digikey Vishay foils are wicked expensive although better spec than the originals in the Datron. Not too many options in the <=5ppm/degC range.Current board uses the following shunts:900R 0.1% 5ppm/degC90R 0.1% 5ppm/degC9R 0.1% 5ppm/degC1R 0.1% 5ppm/degCAll but the 1 ohm will probably need to be at least two resistors in parallel. I'm not a volt nut so I can't justify spending the dough on Vishay foils. (yet)

author: Vgkid
author_rank: Super Contributor
timestamp: February 11, 2017, 02:34:31 am
content: It will be easiest to run resistors in parallel for everything above the 10 ohms and still meet specs. Run precision foils for 1 and below. Contact E.G. Pettis on here to talk pww resistors.

author: Gyro
author_rank: Super Contributor
timestamp: February 11, 2017, 09:33:16 am
content: Having suggested building a current board, I might back-pedal a bit .As I said, current options were pretty rare on Datrons, in favour of external shunts. These do get closer to the scene of the action and minimise voltage drop.It doesn't deprive you of the fun of sourcing the resistors but does avoid switching relays etc. Here's the collection of shunts I put together for exactly this purpose. In practice I use them at 10mV maximum voltage burden...https://www.eevblog.com/forum/testgear/my-shunt-collection-(ucurrent-passive)/msg857960/#msg857960

author: Kennylxix
author_rank: Regular Contributor
timestamp: February 11, 2017, 03:00:55 pm
content: Aaand and now I'm looking at precision current shunt on ebay:)