On Sun, Nov 19, 2023 at 06:24 AM, factory wrote:
The original boards with edge connectors were nickel or gold plated, the ones I saw on ebay looked to be HASL, this could be a problem with the gold edge connector sockets, a warning from an ex-HP designer that they can get quite stuck here;
I prefer my HP TE to be original where possible, but I do have a 1976 prefix design Rev. that got modernized by HP with a 03400-66512 Rev C board from 1984.
I've got quite a few 3400As, can't remember the PSUs causing much trouble, except where an incorrect manual was used by a previous repairer & Ge/Si parts got mixed up, some diodes & resistors changed for biasing, all mine are using Ge power transistors, TO-3 parts are getting pretty much obsolete these days anyway, so finding genuine parts from reputable suppliers is a problem.
Wonder what people are doing with the old but still working A6 boards? Noting the large & small optical chopper assemblies were used in other HP analog meters & some DVMs.
One thing I've never found is a decent readable manual for the later serial prefix of the 3400A, I tried the manual bundle from Artek, the 03400-OSM-90008 is a decent scan of the 1972 manual (marked part no. 01768 on the pages), the 1972 03400-90008 is available for free download, but I haven't checked how much it differs. But the 03400-90013 is the exact same one available by download from Agilent/Keysight, the scan quality isn't great.
Has anyone got a decent scan covering the later variants? i.e. A6 with part no. 03400-66512 Rev A & C,
Also I've found there was an 03400-66512 Rev D board, but the manual fails to cover that. Has anyone got a good picture of that board showing both sides? As I'm currently working on making my own version of this board.
David
David,
I have a PDF of the 03400-90013 manual that I downloaded from Didier's manual site (serial prefix 2415), It contains a readable schematic & parts placement for the 03400-66512 A6 board.? Not sure if the A6 covered is the version you're looking for; I don't know how to identify the board version covered in the manual. Both of my 3400As have the optical chopper (and still working well), so I can't help with a picture of the board you want.
It's the best scan that I've found for the 03400-90013 manual.??
http://www.ko4bb.com/getsimple/index.php?id=download&file=HP_Agilent/HP_3400A_RMS_Voltmeter/HP_3400A_RMS_Voltmeter_Service_Manual.pdf
On the impedance converter; according to the circuit description in the manual, it's just a unity gain non-inverting amp with hi input impedance and low output impedance, so that stage should be pretty easy to replace with many of today's opamps.??
Cheers,
DaveM
