HP 8594E - Page 1
Forum section: electronics / testgear

author: avvidclif
author_rank: Regular Contributor
timestamp: February 17, 2015, 12:35:56 am
content: My new to me 8594E is set to be delivered tomorrow. One of the first things I'm going to do is change the battery after I satisfy myself it's working correctly. Any other suggestions, test, hints, gotchas, etc.It has Options 04 (yeah, high stability osc) and Option 101 that I've read about but don't really understand. It will be fun. It has a RS232 and Parallel printer connections on the back but the option has been crossed out??

author: alex.forencich
author_rank: Frequent Contributor
timestamp: February 17, 2015, 01:33:33 am
content: The battery is rechargeable, IIRC. So there may be no need to replace it so long as you turn it on for a couple of hours to charge it up. If you want to replace the battery, there is a procedure for it in the service manual. Be careful not to discharge the backup super cap. I would also recommend reading off the flatness data and writing that down somewhere just to make sure you don't lose it.Option 004 is definitely nice to have, just make sure you let the oven come up to temp whenever you power it on. Option 101 just lets you do fast sweeps. It's mostly useful in zero span, but in zero span you can just route the video out in the back to a scope and get a much longer record length. Ignore the option label on the back. That just tells you what the factory installed. Take a look at the options listing that you can pull up on the display. Or take the cover off and look at the card cage. If it has an RS232 port installed, then it should work. Well, presuming the interface board is installed anyway. It is possible to install the connector plate without the interface board.

author: dfnr2
author_rank: Regular Contributor
timestamp: February 28, 2015, 07:36:00 pm
content: The battery is a non-rechargeable but long-lasting primary Lithium coin cell, nominally 3V, soldered to the PCB. I just replaced mine yesterday. It was installed in 1996, and was still working, but long overdue for a change. When I took it out, the old battery read 3.02V against a 3.3k resistor, and 3.06V unloaded!The replacement part is the Panasonic CR-2477/HFN, available from Mouser, Digikey, and others.The battery is located on the memory board, which is piggy backed on the main CPU board on the underside of the analyzer. To get to it, you want to do the following:- take off the outer case, and turn the analyzer upside down so you can see the GPIB/Parallel board (although, from your description, you may not have one.)- If a GPIB board is present, remove it.- Gently remove the memory card, by squeezing the heads of the nylon standoffs and applying gently upward pressure on the undersurface of the board. Be careful around the D-connector between the memory card and the CPU board.- Remove the paper cover along the underside of the battery, and desolder it. Replace the battery, replace the paper cover, reverse the above process.- Record the date on the back of the scope.I agree with Alex about trusting the list of options provided by the "show options" utility, rather than the label on the back of the scope.Options 04 and 101 are good ones to have. See if you can snag an inexpensive option 130 (Narrow RBW). However, it seems the options for these analzyers are a good chunk of the difference between the cost of an 859x and 856x on Ebay.Good luck,Dave

author: dfnr2
author_rank: Regular Contributor
timestamp: March 01, 2015, 10:22:13 pm
content: I bought two of these batteries, thinking I could use one in my 8594E, and the other in my 8591E. But the 8591E was had a different CPU, with the battery soldered right onto the board.So, I have one spare, fresh battery for the 8594E, if you want it.Dave

author: avvidclif
author_rank: Regular Contributor
timestamp: March 02, 2015, 01:50:32 am
content: When I replaced the battery in mine I noticed that I lost the date/time but apparently nothing else. It is showing the same levels as before the replacement. I'm still scratching my head over that. My battery was also at the 3v level...

author: dfnr2
author_rank: Regular Contributor
timestamp: March 02, 2015, 02:50:11 am
content: Quote from: avvidclif on March 02, 2015, 01:50:32 amI saw the same thing. Most likely, the battery powers a RTC along with the RAM, but the supercap only powers the RAM.

author: MarkL
author_rank: Unknown
timestamp: March 02, 2015, 02:07:03 pm
content: Quote from: avvidclif on March 02, 2015, 01:50:32 amThe RTC is on the processor board, so when you unplug the NVRAM card (on the newer style processors), you remove battery power from the RTC.If you haven't done so already, I'd highly encourage everyone with a 859x to go through the procedure to backup your calibration data. It takes about 10 minutes and is described in chapter 3 of the Assembly Level Repair Guide, "Backing Up and Reloading Correction Constants".http://www.keysight.com/upload/cmc_upload/All/08590-90316.pdf