My latest aquisition is an HP59401A GPIB Bus Analyser. Got it for US$15.35 - the shipping was $29.99
![Smiley :)](https://www.eevblog.com/forum/Smileys/default/smiley.gif)
(I await Bitseeker's comment of 'Ah, so that's who got it'!
![Laughing :-DD](https://www.eevblog.com/forum/Smileys/default/smiley_laughing.gif)
)
Out of Seattle so my guess was it was from Boeing - and sure enough there's the Boeing sticker on the top. The seller claimed it was taken from a working system. Uh huh - I can't think of a single reason, in 2018, for a GPIB bus analyser being in a production line system (which is the implication I read into 'taken from a working system').
Anyway it doesn't work. Front panel character display shows nothing (though the control line leds seem to be showing valid states). I'm about to dive in and find out what's wrong. I'm guessing power supply (fingers crossed).
I searched and searched but could find no online schematics. Yep, there's an operators manual but no schematics. Fortunately Artek have it so there's another 15 bucks. I'm almost starting to think it might have been cheaper to buy the HP/Agilent usb adapter and have done with it. But I'm into the money pit now.
So why, in 2018, would anyone actually buy this dinosaur (1975ish design)? I'm trying to get Emanuele Girlando's arduino code working! It works fine against my HP5335, HP3325 and HP3456 instruments, but my HP8568 doesn't want to play nice. I'm convinced there's something in the arduino code that's not quite right.
The problem is that the HP8568 locks up after I send it a command with the REN line asserted. By locks up I mean that the display freezes. Switch back to local and it executes the command and the display becomes active again. If I leave REN unasserted the HP8568 behaves properly except that it doesn't light up the REM indicator. And leaving REN unasserted for the other instruments means they never go into Remote mode (but still respond to commands and return data).
Yes, I've considered the possibility that there might be something wrong with the HP8568 but it seems unlikely. My reading of the HP8568 service manual doesn't show anything like a Listen or Talk only mode.