HP 4194A Impedance Gain Phase Analyzer REPAIR, any other owners ? - Page 1
Forum section: electronics / projects

author: oz2cpu
author_rank: Frequent Contributor
timestamp: May 14, 2022, 09:52:09 am
content: this one looks promissing, it boots and runs..I really love this unit, so i really would like to get it running..BUT it beeps, and display the famous "Bridge Unbalanced" hardware error say the manual.I googled a million times, some posts talk about A4 module blown fuse, but there is no A4 module to find. (where should that be located ?)service manual from keysight web is in a terrible compressed low resolution version,so i cant read or understand most of the schematics.Any one got a working unit ? please reply here ?Any one got better schematics : my username at gmail dot com, pleaseI would love to perform some very simple versus measurements:your working unit, to mine defectivelets take a scope, and see what goed in/out of the different BNC connectors, in the same modes, and same settings,I see things i am unsure is right or wrong.

author: jonpaul
author_rank: Super Contributor
timestamp: May 14, 2022, 11:18:22 am
content: Bonjour cher MonsieurMarvelous machine, similaires to 4195A and 4193A with impédance test set 41952AWe have used 4195A 30 yearsThese were designed at Hp and build in collaboration with Yokogawa Japan, uses HP custom SOS CPU.HP extender set and HP signature Analyzer may may be required to troubleshoot.Suggested général proceedure1/ obtain hi res pdf or printed service manual for the serial number range2/ check every power bus for voltage and ripple.Failed lytics, PSU regulators and shorted bypass tantalum caps are common3/In decades old instruments corrosion and oxidation can cause issues especially intermittentPCB to cable and PCB card edge should be unplued and exercised4/ may have built-in self test proceedure5/ if you are located in Scandinavia our old friend Magnus D. might be of assistance, in Stockholm....Further information may be on HP memory project.Manuel might be at BAMA archiveArtech may sell a pdf or printed copy.Bon courage et bon chanceJon

author: oz2cpu
author_rank: Frequent Contributor
timestamp: May 14, 2022, 11:06:27 pm
content: here is my latest video releaseabout this HP 4194Ahttps://youtu.be/X5wNRnbFRwk

author: oz2cpu
author_rank: Frequent Contributor
timestamp: May 15, 2022, 08:45:30 pm
content: here is part 2mostly main unit of HP 4194Ahttps://youtu.be/GsAZFcgaGAk

author: jonpaul
author_rank: Super Contributor
timestamp: May 16, 2022, 06:30:54 am
content: Rebonjourvisual inspection usually reveals little except blown tants or corrosion.As mentioned suggest you find the complete service manual, ( not a bad PDF) and follow proceedure.Extenders and HP signature Analyzer requiredFinally check out the HP instruments forum on groups.io.jonjon

author: oz2cpu
author_rank: Frequent Contributor
timestamp: May 16, 2022, 07:32:43 am
content: so far :found a lot of leaked caps , desoldered a few, and measured their values, most are close to ok values,but leaked conductive puke over the boards, so they need deep clean.. and of course replacement.i will wait with that, until the real error is found and fixed.heard from previous owner, they do recall it was killed by wrong use, measuring audio amplifier gain-phasewhere they forgot attenuators..still no luck getting service manual / schematics in use full quality.no one contacted me so far about that,and also no other owners found.

author: strawberry
author_rank: Super Contributor
timestamp: May 16, 2022, 05:49:10 pm
content: same as Dynacord sl1200 amp, no schematics available. how it works , how to test components and what to expect, recognize previous repair attempts..., after week/month it is fixed