HP 3400A manual, last revision circa mid 1980s

[factory]

Does anyone have late HP 3400A manual that covers the A6 board 03400-66512 Rev C and Rev D? The manual from Agilent/Keysight is a terrible scan and doesn't cover the Rev D board, Artek provided the exact same Agilent pdf too, very unusual as they usually do excellent scans.

Also can anyone help with a good picture of the 03400-66512 Rev D board? both sides please, I'm interested in the differences of the track layout & resistor values.

Thanks David

[Chris55000]

What's the Serial Number of your unit?

There's a good book from Manuals Lib that covers series up to 0979A–13725, however, if my memory serves me correctly, I think "xxxx–66512" and on was used for when a board underwent a major design change – this numbering scheme was applied across the majority of H.P. instruments of the period!

I am given to understand that Hewlett Packard weren't able to obtain the neon–operated photo–chopper assemblies originally used in this voltmeter towards the end of their production life, and they fitted a totally different design of A6 Chopper amplifier PCB that used an LT1052C op amp, and I'm still searching for information regarding this!

Is your A6 board fitted with one of these?

Chris Williams

[Chris55000]

Any help?

Chris Williams

[Chris55000]

. . .Rev C PCB Layout Diagram

Chris Williams

[Chris55000]

PCB A6 03400-66512 RevC Layout Diagram :–

Chris Williams

[Chris55000]

. . .If you need anything better than this I'll have to draw it for you – unfortunately I don't have the manual file this came from, somebody said they would upload the whole manual to K04BB but they never bothered!

Chris Williams

[Chris55000]

03400-66512 PCB A6 Revision D

Chris Williams

[Chris55000]

. . .Further to the above, I can confirm that manuals 03400–90011, 03400–90012 and 03400–90013 are available for free download – all atrocious quality I'm afraid, but '90013 only covers A6 PCBs up to Rev. C – I am trying to get hold of the H.P. Service Notes for this meter, they don't seem to be readily available for download anywhere – I suspect the A6 Rev. D board was only covered by a Service Note, if at all!

Chris Williams

[factory]

I've got several 3400As here of various ages, the 03400-66512 Rev C board (I see you found my picture ) was found in a German made 3400A from around 1976, it had evidence of many repairs in it's working life. This board from around 1984 is being used as a guide to create my own replacement PCB.

The available manual (03400-90013 prefix 2415) covers 03400-66512 boards Rev A & Rev C, with some errors.

The Rev C uses the 14 pin ICL7650IJD (1826-0968) chopper op-amp IC from Intersil and a 1826-0310 8 pin can amplifier IC from Motorola, this is not listed in the HP cross ref charts.

In the backdating changes for prefix 2225, the Rev A board uses the same ICs, with three resistor changes and removal of a pot, the component locator diagram refers to Rev C, this is clearly an error.

When I was looking for more pictures, I found that later 03400-66512 Rev D board (possibly from 1987), still using using the ICL7650IJD (1826-0968) chopper op-amp IC, but the obsolete can IC got replaced with a 1826-1381? (struggling to read the low resolution picture) this would cross to an LT1012CN8, the pot & one resistor are removed, there is a minor difference to the trace above the connector.

Hope this explains why I'm after a better picture of the Rev D board showing both sides, also want to be able to read the resistor codes.
I suspect your right & the Rev D info was only available in a service note.

David

[factory]

Hal on the HPAK group might have a Rev D board, post #140441; https://groups.io/g/HP-Agilent-Keysi...83251222505506

David

[factory]

Originally Posted by factory

Does anyone have late HP 3400A manual that covers the A6 board 03400-66512 Rev C and Rev D? The manual from Agilent/Keysight is a terrible scan and doesn't cover the Rev D board, Artek provided the exact same Agilent pdf too, very unusual as they usually do excellent scans.

A big thanks to Artek, I emailed about the Agilent branded manual that I got sent in error, they were quick to respond with the correct 03400A-OSM-90013 manual which covers the 1982-84 versions (with A6 Rev A & C), excellent quality scans.

And there are now pictures of the A6 Rev D board on the HPAK group, thank you to Hal for those.

David

[Radio Wrangler]

Things were changing rapidly in the true-RMS side of HP in the early 1980s. Loveland had cooked up a new themal converter which went first into the 3335A sunthesiser/level generator. It had the part number 1SB1-0021 thich looks odd for an HP part number.

The South Queensferry SLMS had used the thermopile unit from the 3400 series as its widevband power RMS converter. A few years later the 1SB1-0021 was in use in the 3708A carrier to noise box where it was operating to over 180MHz.

1SB1-0021 was a pair of matched termination resistors, each with a string of matched diodes sensing their temperature.

The microwave/RF power products had their own, quite independent thermal RMS measurement systems. The 478 bolometer head had thermistors in a bridge arrangement with the bridge being DC powered drom a DC amplifier. The amplifier was driven by the differential voltage representing the unbalance of the bridge, so the DC feed to the bridge stabilised with the thermistor impedances right to act as matched loads for the RF. The RF was coupled in via blocking capacitors, with other capacitors doing duty as RF shunts. As you drove the thing with RF, the DC power backed off to maintain the chosen impedance, and so the DCpower was reduced by an amount equal to the RF power being introduced. It was a true DC substitution method within just the thermistors and was not highly reliant on matching. The heads held a second thermistor bridge and worked with a second amplifier. This was used as a reference to compensate the effects of ambient temperature. These thermistor bolometer substitution techniques can be used from low frequencies limited by the thermistor response rates up to optical frequencies.

The 3400 stayed in production through much of this period with little externally obvious change because customers wanted them. They had them written into their test procedures and also into ATE.

That they were great little boxes is evidenced by their production life.

David

[Chris55000]

Just placed my order for the two–volume set – with this and Hal's pics I can make a proper set of 03400–66512 Rev D. Diagrams now!

It looks like Artek have been able to get someone to take over their supply of manuals online following Dave's death last year, am I right?

Chris Williams

[factory]

Originally Posted by Chris55000

It looks like Artek have been able to get someone to take over their supply of manuals online following Dave's death last year, am I right?

Chris Williams

His wife Linda is running both the Artek website & ebay store now, but the dropbox links still reference Dave.

David

[factory]

Originally Posted by Radio Wrangler

Things were changing rapidly in the true-RMS side of HP in the early 1980s. Loveland had cooked up a new themal converter which went first into the 3335A sunthesiser/level generator. It had the part number 1SB1-0021 thich looks odd for an HP part number.

The South Queensferry SLMS had used the thermopile unit from the 3400 series as its widevband power RMS converter. A few years later the 1SB1-0021 was in use in the 3708A carrier to noise box where it was operating to over 180MHz.

Is that odd part number anything like the ones used in the 3484A (option) & the 3403 series?
https://www.eevblog.com/forum/testge...34/#msg3349034

Originally Posted by Radio Wrangler

The 3400 stayed in production through much of this period with little externally obvious change because customers wanted them. They had them written into their test procedures and also into ATE.

That they were great little boxes is evidenced by their production life.

David

Some comments on Groups.io as to why they needed to use the LT1012 as the meter amp in the final version, though there is that DC output that must have been used with ATE setups.

David