[FIXED] Agilent 34401a repair - dead GPIB

[usagi]

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?

[Dr. Frank]

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

[usagi]

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?

[Tony_G]

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.

[usagi]

100% confirmed the connector is perfect.

100% confirmed an IC is blown. waiting on mouser order to arrive now.

[HighVoltage]

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

[usagi]

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

U701 is fine.

[HighVoltage]

U701 is fine.

Ahh, which IC do you think is blown?

[usagi]

replaced blown IC, GPIB now works. again

[TheSteve]

Excellent!!!

Please do post which IC you actually changed to make it work though.