| Products > Test Equipment |
| HP/Agilent 34970A Teardown |
| << < (7/7) |
| DoricLoon:
Much to the wifes frustration I've spent a while fault finding this error 625. There is indeed two way communication between main processor and IO processor. When the power on button is pressed the main processor sends out a 400mS pulse on the data line after 15mS of that pulse the IO processor reset is taken high and remains high for the rest of the pulse. 62mS after the reset returns low the IO processor sends a 53uS pulse to main processor. Further 15mS and main processor sends 2 11 bit frames of data to the IO processor. The fact that I can change interface type from RS232 to GPIB and see the interupts change means the IO processor has responded to data from the main processor. I don't have a card for this thing yet. Waiting for a couple to arrive. Going to try to connect RS232 to see if I can actually talk to the unit? Any ideas? |
| DoricLoon:
Have connected to RS232 and Connection manager finds an instrument but doesn't identify iteslf and doesn't respond to *IDN just gives a time out. I have set COM port 1 with same settings as those of the instrument. |
| DoricLoon:
Had another go at the 34970a today and think I may have found something? I can change the baud rate of the RS232 interface and see the baud clock on the TL16C550CFN alter so the IO processor is definately responding to main processor command. I checked the data lines between the IO processor and the two bus management IC's and could see data switching. I then selected GPIB and each of the data lines shows the same signal. As per attached PNG. I'm an electrician trying to learn electronics so my knowledge is pretty rudimentary. Looking at the signal it appears to me that the rise time of the signal is way off. With GPIB selected the signal is constant. RS232 selected and data is changing but after taking a closer look that horrible rise time still exists. Should I desolder the GPIB controller and see if the data lines improve? |
| voltsandjolts:
FYI this is a long dead thread, just waking it up to add some info. This thread pops up when searching for a part number for the 34970A front panel encoder. The Keysight info for the encoder and knob are: 0960-0961 MECHANICAL ENCODER 2 BIT 24 POSITION 34970-87401 34970A KNOB As mentioned above, it's a Bourns ECW and I suspect the exact PN is ECW0J-C24-BE0024L no detents, smooth rotation (as supplied by Keysight) Currently available at Mouser for £3.40 ...or if you want detents... ECW1J-C24-BC0024L 24 detents Currently available at DigiKey for £4.80 |
| Navigation |
| Message Index |
| Previous page |