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

author: skennedy
author_rank: Contributor
timestamp: July 21, 2015, 05:30:14 am
content: I have been watching ebay for a few years waiting for a reasonably cheap spectrum analyzer to come up for sale. Shipping cost to Australia was a bit issue for HP 8566 and 8568 units so a slightly more modern unit was desirable for weight alone. What do you know but a few weeks ago three came up from the same seller as parts all apparently from a Taiwanese university. Being a EE PhD student myself I knew that equipment generally gets badly treated when rarely used and sits unused for the majority of the time but maybe worth a look.I won the 8594E 9kHz to 2.9GHz spectrum analyser with a lot of options: 004 High Stability time base, 021 HPIB,101 Fast ADC, 102 AM/FM Demodulation, 105 Gated Sweep and most importantly 130 Narrow Resolution Bandwidths. The photos in the listing showed that there were a number of errors including ADC GND which looked potentially major. The CRT also was quite hard to read and misaligned. Hoping that the repair wouldn't be as painful as my Tektronix TDS 544a oscilloscope I took the punt.Photos:The photo from the ebay listing.Once I received the unit I carefully turned it on. The ADC-GND and ADC-2V errors appeared. A terrible burnt smell also filled the room. It was time to take off the case and have a look inside.Inside Bottom:Top showing card cage and some RF voodoo shieldsTop again showing the card cage and psuPowering the unit on with the case off I noticed that the +15VF supply led was not on.So I removed the PSU and disassembled. Unfortunately there was nothing obvious wrong and certainly nothing that was making the smell.Continuing the sniff test I kept looking for the culprit. On the bottom I removed an rf board and the smell became a lot stronger.Found it! A 6.8uF tantalum had blown itself up. Looking at the service manual schematic I found that it was a decoupling cap for the ADC 15V supply.I was slightly worried that some of the other components nearby had been damaged including the ADC.I removed the capacitor and powered the analyzer back on. The power supply had returned and the error had disappeared.Turning the screen intensity knob I was able to have a nice bright screen and moving the image using the Cal menu re-centered the image.The self passes as does the calibration of amplitude and frequency.Looks like I was a lot luckier with this repair than my last.

author: BravoV
author_rank: Super Contributor
timestamp: July 21, 2015, 05:35:17 am
content: Nice score and worth the gamble, and apparently you won !

author: PA0PBZ
author_rank: Super Contributor
timestamp: July 21, 2015, 11:30:40 am
content: What are the four yellow three-legged components in the PSU picture? They seem to be marked Dxxx so (double) diodes? Never seen that, they look like 3 legged tantalums

author: iso14000
author_rank: Contributor
timestamp: July 21, 2015, 12:03:47 pm
content: congratulation!I keep personnaly my own HP8594 in a 24°C temperature premise, too much precious.....

author: tec5c
author_rank: Frequent Contributor
timestamp: July 21, 2015, 12:22:20 pm
content: Nice score! I have a very similar unit though I can't recall the model off the top of my head.Mind if I ask which Uni you are doing your PhD at?

author: PaulAm
author_rank: Frequent Contributor
timestamp: July 21, 2015, 12:39:22 pm
content: The only thing better than a blown cap is operator error

author: AF6LJ
author_rank: Unknown
timestamp: July 21, 2015, 01:14:13 pm
content: Nice score.

author: jlmoon
author_rank: Unknown
timestamp: July 21, 2015, 03:40:44 pm
content: Quote from: PA0PBZ on July 21, 2015, 11:30:40 am"Double Trouble"

author: skennedy
author_rank: Contributor
timestamp: July 21, 2015, 10:24:22 pm
content: The yellow three-legged components are 6.8uF tantalum capacitors. I've never see them before either (or can find replacements easily) but assume that the extra leg would be for stability just as with large electrolytic capacitors. Seems this instrument was built during the love affair with the things. Glad they are so unreliable!I'm doing my PhD at Monash, looking at EMI from integrated circuit devices. Hopefully I will be able to use this to do some measurements.

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: July 21, 2015, 10:44:18 pm
content: Hi,The three legged tantalum capacitors were made so that it was impossible to put them in backwards. Here is a Vishay datasheet:The center lead is positive.Kemet also made some like this.Regards,Jay_Diddy_B

author: dfnr2
author_rank: Regular Contributor
timestamp: July 22, 2015, 01:42:30 am
content: Wow, you snagged that for a song. Great score!

author: VE7FM
author_rank: Newbie
timestamp: July 22, 2015, 01:59:32 am
content: That was a great score. Well done indeed and enjoy your new toy.We need a stats thread to show what percentage of stuff people were able to fix after buying it as broken/as-is etc on ebay.

author: PA0PBZ
author_rank: Super Contributor
timestamp: July 22, 2015, 10:25:12 am
content: Thanks for the explanation guys. I really can't remember ever seeing them before.

author: TerraHertz
author_rank: Super Contributor
timestamp: July 22, 2015, 03:21:42 pm
content: Wow. Congratulations!So there are reasons to appreciate tantalum caps after all.Are you going to say how much you won it for? Speaking as someone with very little hope of ever owning a nice spectrum analyzer.

author: Shock
author_rank: Super Contributor
timestamp: July 22, 2015, 04:07:52 pm
content: One extra leg double the smell when it blows.

author: Shock
author_rank: Super Contributor
timestamp: July 22, 2015, 04:13:03 pm
content: Quote from: TerraHertz on July 22, 2015, 03:21:42 pmLess than $427.50 USD shipped is my guess.

author: skennedy
author_rank: Contributor
timestamp: July 22, 2015, 10:39:58 pm
content: The total was $427.50 USD. Analyser was less than half at $202.50. I think the location worked in my favour as I would doubt most people is the US would be willing to pay that much for shipping, whereas $150 for shipping from the USA is fairly standard with larger pieces of test equipment. I was interested in a 8568B that was listed for $429 USD and shipping was $440USD. Glad I waited for this one.There was a HP 8560E that sold the other day for $103.23 with $138.90 as the quoted shipping cost. It was missing a few parts (including the membrane switches) so it was a much larger gamble and it seems that it has just been relisted by the purchaser.There is quite a lot of cheap equipment going around, mostly with fairly minor faults that scares people off. A lot of the time it is just about waiting for the right thing to come up for sale. I have been pretty lucky with what I have purchased over the last few years. The nice thing about equipment that is a bit older is the comprehensive service manuals and schematic that should be available.The plummeting australian dollar is has started to hurt quite a lot recently. Long gone are the days of $1.1USD = $1.0AUD

author: MadTux
author_rank: Frequent Contributor
timestamp: July 23, 2015, 02:55:05 pm
content: That HP 8560E with a few parts missing went for $103:http://www.ebay.com/itm/HP-Agilent-Keysight-8560E-Spectrum-Analyzer-30hz-2-9-GHZ-/261961450276?nma=true&si=MW5f90tnbWiMc%252FKixmPq8PHnDcA%253D&orig_cvip=true&rt=nc&_trksid=p2047675.l2557Then a few days later the guy who bought that thing sells the same HP 8560E with a few more parts missing for $179:http://www.ebay.com/itm/HP-Agilent-Keysight-8560E-Spectrum-Analyzer-30hz-2-9-GHZ-/291520956900?pt=LH_DefaultDomain_0&hash=item43e000c9e4&nma=true&si=MW5f90tnbWiMc%252FKixmPq8PHnDcA%253D&orig_cvip=true&rt=nc&_trksid=p2047675.l2557LOL & WTF

author: Stray Electron
author_rank: Super Contributor
timestamp: July 24, 2015, 03:43:42 pm
content: Quote from: skennedy on July 22, 2015, 10:39:58 pmI just looked, $1.0AUD = 0.73 US. Wow! What happened? I don't think the USD has that much world wide so is there something go that has caused the AD to drop that badly?NICE catch on the SA! Ebay has lots of bargains for those that are willing to wait for the right thing to come along.

author: KJDS
author_rank: Super Contributor
timestamp: July 24, 2015, 04:44:27 pm
content: Quote from: Stray Electron on July 24, 2015, 03:43:42 pmChina has cut back buying primaries.

author: melo
author_rank: Newbie
timestamp: February 17, 2018, 03:51:43 pm
content: I used to write software for the 90 series analyzer. Was fun to see the processor board with the 4 EPROM's, everyday I would start my day removing those chips, erasing them, burning a new Firmware image and re-inserting them. Before getting down to the business of writing measurements for DECT, CATV, GSM and broadcast TV. Great days!

author: scopeman
author_rank: Frequent Contributor
timestamp: February 17, 2018, 07:37:37 pm
content: Melo,I have worked on a bunch of these and the 856X series including the HP8590A "volkswagon" analyzer. I have converted a few of the option 001 75 ohn HP8590A's to50 ohm but one thing I could never figure out is how to get the converted instrument to stay and power up in 50 ohm mode. Any hints there?SamW3OHM

author: Bicurico
author_rank: Super Contributor
timestamp: March 21, 2019, 11:19:44 pm
content: I know this is more than a year old, but here it goes:Remove 001 option:PresetFrequency, -2001 HzAmplitude, More 1 of 2, Input Z 50-ohmAmplitude, Scale Log Lin (Log), More 1 of 2 Amptd Units dBmAmplitude, Scale Log Lin (Lin), More 1 of 2 Amptd Units dBmCal, More 1 of 4, More 2 of 4, Service Cal, Stor Pwr On UnitsRegards,VitorPS: I have not tested this myself.

author: scopeman
author_rank: Frequent Contributor
timestamp: March 21, 2019, 11:47:11 pm
content: Thanks Victor. I have since sold that analyzer but I will keep this info for the next time.All the best,SamW3OHM