HP 8903A : Audio Analyzer : teardown - Page 1
Forum section: electronics / testgear

author: psykok
author_rank: Frequent Contributor
timestamp: July 07, 2014, 10:29:26 am
content: Hi,So, I broke my piggy bank to couplet my audio lab. I bought a HP 8903A audio analyzer.It's a really nice instrument with a lot of functionality, I will never use all of them but it will be very handy to test audio amplifiers.This item was sold as not working and with 3 broken knobs (power switch and the two gnd/float switch), after changing two fuses I can say that everything is working.I still need to change the knobs but it's only a cosmetic thing.I have made some quick pics during the unboxing:I will do a complete tear down in the next weeks.Regads,Alex

author: MattSR
author_rank: Regular Contributor
timestamp: July 07, 2014, 11:10:18 am
content: Awesome bit of gear, isn't it? I recently splurged on an HP 8901B modulation analyzer so I can align and calibrate radios. I just love gear of this vintage, it's so solid and well designed.

author: psykok
author_rank: Frequent Contributor
timestamp: July 07, 2014, 11:27:19 am
content: Quote from: MattSR on July 07, 2014, 11:10:18 amYes it's build like a tankAgilent has also a more actual Audio Analyzer, the U8903Ahttp://www.home.agilent.com/en/pd-1661494-pn-U8903A/audio-analyzer?&cc=CH&lc=ger

author: unicornio
author_rank: Contributor
timestamp: July 07, 2014, 07:47:22 pm
content: this series of instruments from HP in the 80's is for me the highest quality, intuitive design, and durability, of all hp history... so I think you'll have a very good intrument for life ...good luck!...i buy one day, in an electronic dismantling surplus, two units of the 3455A digital multimeter, both deliberately destroyed and covered with mud blows ... I take both, and after I clean, and using parts from both units i GOT to have a good functioning working unit. I take it to calibrate to a laboratory that I had free access, and it was perfect!. this is a robust instrument device with an amazing precision and stability ...and for hi fi hi-end testing, I have not seen any as accurate and useful as the audio spectrum analyzer 3580A, oldest instrument, but also an indispensable tool for analyzing measuring cross harmonic distortion and intermodulation cross in the audible band ... I recommend it if you find one cheaper out theregood day, mate!

author: radhaz
author_rank: Regular Contributor
timestamp: July 08, 2014, 02:40:23 am
content: I bought an audio analyzer a while back:vp7723afbyryuuohWhen I got it, it was filthy, and measured bad.vp7723acbyryuuohvp7723aabyryuuoh

author: Richard Crowley
author_rank: Super Contributor
timestamp: July 08, 2014, 03:57:33 am
content: That Panasonic analyzer looks remarkably like HP/Yokogawa. With the buttons, and panel, and chassis construction, etc. Is it Yokogawa with a Panasonic badge?

author: radhaz
author_rank: Regular Contributor
timestamp: July 08, 2014, 04:21:01 am
content: It's a Panasonic. Many of the Japanese audio analyzers from that period look similar. I bought my VP-7723 based on what this guy buys:http://amp8.com/amp-etc/etc-etc/etc-etc.htm

author: psykok
author_rank: Frequent Contributor
timestamp: July 08, 2014, 07:16:01 am
content: Very nice Panasonic equipment, the VP-7723A is the digital version of the VP-7721A.The VP7723A is much recent as the HP 8903 series and has a much better noise floor ... but it will cost 3 or 4 time more.For a hobbyist like me the 8903 is more less the best Audio Analyser you can get, a pro will go for the world wide standard : Audio Precision (will cost a lot of $$$$$$$)And if you have such a HP 8903, you can use the software suite from pmillet to do a lot of automation using the GPIB port:http://www.pmillett.com/hp_8903_software.htm

author: psykok
author_rank: Frequent Contributor
timestamp: July 08, 2014, 07:21:30 am
content: Quote from: unicornio on July 07, 2014, 07:47:22 pmThe Hp 3580a is nice but I prefer the 3561AI'm slowly also a HP instrument fan but for the spectrum analyzer I have recently repaired a Ono Sokki CF350ZThe only complain I have with this SA is the limitation of 40KHz but for audio stuffs it can be enough.Alex

author: psykok
author_rank: Frequent Contributor
timestamp: July 09, 2014, 10:54:30 am
content: Hi,And now the teardownAlex

author: tri-comp
author_rank: Newbie
timestamp: August 24, 2014, 08:46:17 am
content: Hi,I un-boxed my VP-7723A this week and had a little time to take it apart.Mainly to look for cap's with high ESR and sure enough; they are there.Several 10uF & 22uF cap's are off and needs to be replaced and now comes the real reason for this post:The cap's are BI-POLAR.All are Panasonic SU-series and therefore of the bi-polar type.You should of course keep that in mind when replacing them.Farnell stocks the SU-cap's and at reasonable prices even.Here's a link to the Panasonic datasheet:http://industrial.panasonic.com/www-data/pdf/ABA0000/ABA0000CE97.pdfAnyone has the schematic's ?rgds,/tri-comp