HP 8568/85662 bus interconnect cable. - Page 1
Forum section: electronics / repair

author: rob.manderson
author_rank: Regular Contributor
timestamp: July 31, 2016, 01:51:49 am
content: I'm hoping someone has a diagram of which wires go to which pins on the end that plugs into to the RF section.The cable that came with my setup was decidedly temperamental and the plug that goes into the RF section was extremely loose. Using a pair of very fine tweezers and high magnification I found that the contacts had lost temper - if I moved the contact it didn't spring back, it just stayed where I left it. So I ordered a replacement connector, which didn't exhibit the same looseness when plugged into the RF section.So I sat down and drew a diagram of which wires went to which pins. Double checked it. Then I un-soldered each pin and, as I un-soldered, it noted once more the colouring of the wire and cross checked it with my diagram. Sounds like I did everything right.So when it comes time to transfer the wires to the new connector I discover I've made a few errors in the diagram. I've noted down wires that don't exist - and doubled up on more than one. So much for double check and then check again.I've seen references around the net to the manual containing a wiring diagram but if it's there I can't find it. I bought the (excellent) Artek manual set (all six manuals) and I've just been through them page by page. The 85662 manual lists the D-SUB connector pins by function but not by color code. If worst comes to worst I'll trace each pin from the A15 processor assembly to the matching pin on the back panel of the RF section - then match it up by means of the reverse path from the 85662 to the wire but I'm hoping someone has already done that and is willing to share.If I have to do it myself I'll at least post the diagram here so someone only has to do it once!

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: July 31, 2016, 03:52:41 am
content: Hi,I have attached the wiring list available in the files section of the Yahoo Groups HP/Agilent Test Equipment.I have built one of these cables before.Good luck!!Regards,Jay_Diddy_B

author: rob.manderson
author_rank: Regular Contributor
timestamp: July 31, 2016, 04:24:17 am
content: Thanks. This will save considerable sweating through Phoenix heatMuch obliged.

author: PaulAm
author_rank: Frequent Contributor
timestamp: July 31, 2016, 09:09:56 pm
content: Those cables are a pain to build. I ended up building a microprocessor controlled cable verifier with the wiring map in it to help me make the cable. It doesn't help that it's not a straight 1:1 cable.AFAIK, the color code is immaterial; you just need to be sure the right pins are interconnected.I use crimp connectors. That wayifwhen you make a mistake you can just pop the pins out and swap them around.

author: rob.manderson
author_rank: Regular Contributor
timestamp: August 01, 2016, 01:15:29 am
content: I like that crossed out ifYep, it was a pain to make and I'm not happy with the result. The replacement plug doesn't fit the original HP shroud and a search doesn't turn up anything based on the part number - I suspect it's a HP special. I'm thinking of ordering a replacement DSUB connector and remaking the entire thing rather than using the original cable - at least that way I'll be able to put the shrouds on!I promised to post a listing by wire colour but it's done now and I dare not disturb it too much. The yahoo group document was an immense help - I established that I'd only made a mistake on three wires. It was relatively easy to check continuity from the DSUB to each wire at the other end and the document was correct so I think anyone else needing to follow this path can get there more reliably by using it rather than a colour table.The analyser is now up and running - next fault to solve is that the resolution BW's below 3 KHz don't work - no signal at all. There's no 18.4 MHz signal coming from the Step Gain Assembly into the Bandwidth assembly and someone's been there before me - the crystal is a ring in - not the original part number and you can see that they've soldered a new crystal in. It *is* an 18.4 MHz crystal by it's part number. It's a pretty simple circuit and the transistor checks out ok. I suspect I need to mess around with the factory select component values in that part of the circuit.The self-cal won't finish without the res bandwidths working so I don't yet have an idea of how well the rest is working though it looks pretty flat across the range on my HP 8540B (500 KHz-550 MHz).