Keysight/Agilent (HP) 1141A Differential Probe and Power Module 1142A - Page 1
Forum section: electronics / general

author: Mechatrommer
author_rank: Super Contributor
timestamp: September 03, 2013, 08:51:41 pm
content: Thanks to Alexei.Polkhanov (and jram112) for posting at the right moment few days ago. now i got it at $50, shipping is more expensive at $60 running half the globe. i only have 3 issues with this item:1) the seller lied, he said it is broken and for part only, which is not (with minor fix). he is honest though that there is no attenuator included.2) i dont have proper equipments to re-calibrate it (or ensuring thereof) after all these bing bangs. although its alot better (after quick test) compared to my pathetic DIY probe.3) it wont have proper and specialized place in my congested lab and wont be in serious action for sometime.enjoy the porn... (fwiw the helping hand and power cord are not included in the purchase, its originally mine)

author: free_electron
author_rank: Super Contributor
timestamp: September 03, 2013, 11:20:13 pm
content: resolder that hybrid !These boys run so hot they de-solder themselves over time ...very careful if you are going to use that probe without the attenuators or dc block ! it can have max 4 volts differentially and 40 common mode without attenuators !

author: Mechatrommer
author_rank: Super Contributor
timestamp: September 04, 2013, 12:25:01 am
content: thanks for the info. i'm quite phobia touching anything near the input stage i'm afraid my fingerprint or my nasty flux and alcohol will screw the performance. it was a gamble buy, i thought if its truly damaged then its only for my educational purpose only. but since its somehow working, next plan... mod, create diy compensable attenuator, amplify the puny ±300mV output, anything, i got the main engine already (the hybrid) i will learn from this, but until i get a free time and "free electrons" to play with it again.

author: free_electron
author_rank: Super Contributor
timestamp: September 04, 2013, 02:01:04 am
content: don't mess with it. you're only going to make it worse. this is a very good probe !i will post some pictures of what the attenuator blocks look like inside. i have all of em.resoldering the hybrid : simply use no-clean flux in a pen. apply some flux and reheat the existing solder joints one by one using a fine solder tip. do not add fresh solder. the flux will do its work.

author: Mechatrommer
author_rank: Super Contributor
timestamp: September 04, 2013, 09:20:29 am
content: Quote from: free_electron on September 04, 2013, 02:01:04 ami'm aware of this. thats why i'll need to be as nondestructive as i can, which means adding extension (plugged in) to existing circuit, not hacking or cutting it.Quote from: free_electron on September 04, 2013, 02:01:04 ammy dream will come true then, please do so sir! but also please don't mess with it(other than taking photos only) i know from reading its ceramic layer i believe special type too. i've taken some photo samples online (example below), i need some imagination on how to dismantle the attenuator.thanks for soldering technique advice, that will be helpful.

author: Mechatrommer
author_rank: Super Contributor
timestamp: September 04, 2013, 09:49:37 am
content: and this is from the service manual... shouldnt be that hard to build is it?

author: free_electron
author_rank: Super Contributor
timestamp: September 04, 2013, 12:33:02 pm
content: The attenuators are easy to dismantle. Take out 1 screw and they slide open.

author: Mechatrommer
author_rank: Super Contributor
timestamp: July 20, 2014, 11:51:17 am
content: Quote from: free_electron on September 04, 2013, 12:33:02 pmno screw, 2 clips only and off it goes, this is how it looks sch vs real pcb... so now i got it and can test my 1141 unit.100x attenuator:all R are using pcb "carbon" material or so. topmost and bottom most C in schematics are using pcb capacitance as in the picture.ac coupler:esp the ac coupler, it looks cheap and normal pcb, i believe the xtra $100-$300 or so cost are for that agilent sticker and hp silkscreen.

author: Neganur
author_rank: Unknown
timestamp: April 12, 2015, 02:10:54 pm
content: Don't think my question justifies a new thread:Any idea what the thin film resistor values of the attenuators are? the pot in the middle looks like 5k (marked 502).

author: Mechatrommer
author_rank: Super Contributor
timestamp: May 15, 2015, 12:09:00 am
content: Quote from: Neganur on April 12, 2015, 02:10:54 pmsorry i didnt notice this post, the notification must be lost in the noise. until baltersice sent me a PM this morning asking the same question. so here is what my poor uni-t ut71a can measure. it cant measure the big red, brown and purple caps, the reading jumping all over, usually this indicates large value capacitance, not sure.... the middle trimpot measured 4.5Kohm, but i think it should be 5Kohm as you've stated... fwiw...