HP 34970A, errors 740, 741, 747, 748

• HP 34970A, errors 740, 741, 747, 748
  Posted by Honza on 19 Feb, 2015 19:55
• Could someone help me identify faults at HP 34970A unit which I bought via online auction.
  First I thought that all errors are caused by leaking battery but the new battery didn’t help.
  The unit shows errors 740, 741, 747, 748 after a self-test run.
  Another detected faults:
  -   after switching on (push the on/off button only, the unit is plugged all the time)the unit can‘t remember a communication HPIB or RS232 setting, it’s back in default/factory setting; once I set up again communication RS232 is working (tested), I’m not able to checkHPIB status.
  -   UTILITY setup:
    - the unit remembers the time and date settings
  - CAL SECURED changes to UNSECURED after switching off
  - PWR ON RESET changes to LAST after a few time switching off
  - I get error 741 by change DMM ENABLED – DISABLE
  
  It looks like when I adjust the equipment it’s working fine until the switching off. As per my understanding (and tips on web) the 740 serie errors are mostly caused by a defective FRAM (U450, U201). Or might be there an another problem? Many thanks !
  
• #1 Reply
  Posted by free_electron on 19 Feb, 2015 20:05
• jep. your FRAM is corrupted.
  
  open the machine, unplug the connector going from the DVM module to the mainboard and power up.
  if all goes well you have no errors.
  
  if you have errors most likely one or more traces underneath the leaky battery have been eaten away. and or the fram that sits right next to the battery has its pins eaten ... i've seen that at least twice .
  
  if you have no errors then the fram on the dvm module is hosed. you need a new fram with data in it. that will power up the machine and then you can calibrate it.
  
  
• #2 Reply
  Posted by Honza on 20 Feb, 2015 19:26
• Thanks for your answer. I checked it, there are still errors but it doesn't look lik the battery has eaten pins or traces, see the picture.
  Do you have any other idea? Thank you.

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• #3 Reply
  Posted by free_electron on 20 Feb, 2015 20:04
• see that little 8 pin devices labeled 24c02 ? that is your problem.
  
  it has losts its data and is wonky.
  
  that chip needs replacing and programming with the config.
• #4 Reply
  Posted by Honza on 22 Feb, 2015 22:56
• Quote from: free_electron on 20 Feb, 2015 20:04

  see that little 8 pin devices labeled 24c02 ? that is your problem.
  
  it has losts its data and is wonky.
  
  that chip needs replacing and programming with the config.
  

  
  I saw in discussion that some time ago you offered this device,  is it still available? Or the image file at least? Thanks.