Upgrading a DATRON 1061 to 1061A

[DC1MC]

Hello after a long while  , finally I had some time to update this topic, so first the executive summary:

- It's perfectly possible to transform a 5.5digits Datron 1061 in a 6.5 digits 1061A, there is no hardware difference and you're not losing any functionality, the device after 30yrs+ of operation should stabilize enough for 6.5 digits and I wasn't observing any differences in components on the analogue boards. Also, the readings are stable and reproducible.  .
Any (success) stories, please post them here.

Other thread to read regarding similar subject:
https://www.eevblog.com/forum/repair/datron-1062-dmm/
https://www.eevblog.com/forum/testgear/searching-for-datron-1061a-firmware/

Now the gory details:

• If your device it's not stable and good calibrated as 1061, it will become WORSE after modification !!!, please examine the nice threads dealing with re-capping (a must !!) and removing sources of drift ( aged optocouplers, corroded IC pins in sockets), only proceed when your 1061 it's fully in specs.
  
  The firmware on the digital board it's tightly coupled with the firmware on the GPIB board (indicated in the archive as M3), the bloody thing it's practically memory-mapped and any mismatch will just produce psychedelic displays and scary relays clacking !!!
  
  Again the GPIB board: because it's connected to the digital board with some kind of ribbon cable and the data bus it's a bit anemic strength, older 2732 (21V) memories combined with improvised adapters may not work the first time, try another EPROM or the best, try a 2532 if you have means of programming it. On the digital board, even the 21V orlder 2732 are working very good, because the traces are short, one can try first with the GPIB connector to the digital board disconnected (big 24pin header) for experimentation.
  
  Calibration: You WILL lose some stored NVRAM constants, and after the first startup there will be huge offsets for zero values, that is because it's stored in slightly different locations in the NVRAM, putting a short at the input and applying the "Input Zero" button MORE THAN ONE TIME for all available modes starting with DCV, after it got heated for at least 1hr, will solve the situation and the values will remain OK after power-cycle, of course, if you decide to keep the device as 1061A, the calibration procedure described in the manual should be done, not the part with fiddling with the analog board trimmers, but at least the front-panel calibration.
  

F.A.Q:

Q0) If I decide to return to 1061 5.5 digits after experimenting with the 1061A mode, am I at risk of losing irreplaceable calibration data, will these experiments damage my device ?
A0) No, except for the funny zero values nothing it's lost when going back, I've especially tested with my little collection of resistors and voltage references, same values were read after doing "Input Zero2 button few times after letting the device run for 1-2hrs.
Do NOT activate the CALIBRATION key if you don't know what you're doing or before your new firmware it's installed AND tested, this WILL destroy your calibration data, read the manual regarding calibration a few times !!!
Of course, basic EMP protection should be observed when working, remove the power cable, use an anti-static mat, ground yourself, CAREFULLY remove and reinsert the EPROMs in their sockets.
Also if you WRONGLY insert the EPROM chips in the sockets (rotated, shifted) or fail to observe the basic precautions above, you WILL destroy your device, this is not a complex job, but also not for complete newbies, I disclaim any responsibility, if you break your Datron, you've got to keep all the pieces yourself.
 

Q1) I did the modification, but I see the same number of digits, how do I switch it to the 6.5 mode ?
A1) Press the "Input Filter" button, in few seconds you'll have an extra digit.

Q2) It it possible to have 6.5digits mode with the filter off ?
A2) Not that I know off, most likely no.

Q3) In the attached archive I'm seeing two versions, -19A and -20, which one did you use ?
A3) Because my 1061 used for upgrade is fully featured: Ratio and Back Input, OHM, DVC, ACV, DCI, ACI I've used -20, try both, but start with -20.

Q3) I don't want to use clumsy EPROM adapters, I've got myself some TMS2532 devices, where do I get a cheap programmer to program them ?
A3) I wish I know myself, if you know about something around 6-70EUR that can do the original TMS2532 and 2532A, please let me know as well.

Q4) Could you upload the firmware archive to Datron-Wavetek@groups.io  and/or KO4BB.com, for safe keeping ?
A4) No, but could you, do you already have an account there, because I don't, if so please fell free to upload it.

Also in the end, a heartfelt thank you  to the member that provided the images but didn't want to do it publicly, you know who you are  .

 Cheers,
 DC1MC

[DC1MC]

So I was thinking to show you some pictures of the newly minted Datron 1061A  BEFORE the calibration, just with input 0. Also some observations about the current and dB ranges.
Also to recommend a good 2732 EPROM seller for DE, no connection, just a very happy customer  , I have removed the odd pieces that I've had installed in the adapters and ordered 10x 21V type ST M2732A-2FI and 10x 12.75V NatSemi NMC27C32BQ-200, both of these EPROM types work in all roles, either in the mainboard or GPIB board, I left the mainboard 21V and one 12.75V in the GPIB board, but you can use any of them in whatever place in the device  .

The  bay link is: https://www.ebay.de/itm/10-Stk-2732-32Kbit-EPROM-Speicher-Schaltkreise-ICs-Lagerware/302874412108 and you have to ask explicitly for which model you want, real NOS devices for 1,80EUR a piece it's a steal  .

Now if somebody around Mannheim (ca 50-100Km radius) has a good calibrator and wants to deal 1-2h in week-end with an old guy and his Datron(s) please PM me, I'll try to make your time worth  .

EDIT: EPROM Programmer used: Chinesium TOP2004 with XP software running in am XP VirtualBox installation on Linux Mint, worked always perfectly   .

Enjoy the pictures,
DC1CM