[FIXED] Agilent 34401a repair - dead GPIB

• [FIXED] Agilent 34401a repair - dead GPIB
  Posted by usagi on 18 Apr, 2017 08:47
• Picked up a used 34401a off ebay. The unit passes self test without errors.
  
  RS232 works but GPIB does not.
  
  Is there a common cause of failure for 34401a GPIB ports?
  
  I'm guessing either U703 (75ALS162) or U702 (75ALS160) is bad. Is there any way to tell which one?
• #1 Reply
  Posted by Dr. Frank on 18 Apr, 2017 09:56
• Hello usagi,
  
  see manual p. 92: 'Only one interface can be enabled at a time'.
  
  So I assume, that you have to enable 'HP-IB / 488' first, in the I/O menu, see p. 162, and then it should work.
  
  Frank
• #2 Reply
  Posted by usagi on 18 Apr, 2017 17:11
• Quote from: Dr. Frank on 18 Apr, 2017 09:56

  Hello usagi,
  
  see manual p. 92: 'Only one interface can be enabled at a time'.
  
  So I assume, that you have to enable 'HP-IB / 488' first, in the I/O menu, see p. 162, and then it should work.
  
  Frank
  

  
  i know this already  i had to go into those menus to enable RS232 in the first place, since it came with GPIB interface enabled by default.
  
  so I can confirm GPIB is 100% busted.    GPIB works on my other devices - keithley 2015 and R&S cmu200.
  
  so do you know which exact 34401a IC to verify for GPIB troubleshooting?
• #3 Reply
  Posted by Tony_G on 19 Apr, 2017 20:38
• I just repaired an 11713A that didn't work with GPIB by resoldering the GPIB connector - Might be worth giving it a try if the connector is soldered direct to the board in those devices.
• #4 Reply
  Posted by usagi on 20 Apr, 2017 07:24
• 100% confirmed the connector is perfect.
  
  100% confirmed an IC is blown. waiting on mouser order to arrive now.
• #5 Reply
  Posted by HighVoltage on 20 Apr, 2017 07:39
• Once you exchange the GPIB controller it should work perfect again.
  
  
• #6 Reply
  Posted by usagi on 20 Apr, 2017 08:25
• Quote from: HighVoltage on 20 Apr, 2017 07:39

  Once you exchange the GPIB controller it should work perfect again.
  

  
  U701 is fine.
• #7 Reply
  Posted by HighVoltage on 20 Apr, 2017 08:44
• Quote from: usagi on 20 Apr, 2017 08:25

  
  U701 is fine.
  

  Ahh, which IC do you think is blown?
  
• #8 Reply
  Posted by usagi on 23 Apr, 2017 03:16
• replaced blown IC, GPIB now works. again
  
  

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• #9 Reply
  Posted by TheSteve on 23 Apr, 2017 03:39
• Excellent!!!
  
  Please do post which IC you actually changed to make it work though.