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Are you able to put up an image of what you are looking for, might help folk
understand more clearly what you are after.
Regards
Nigel

---

Joe and Szabolcs: thanks for the ideas! I have not yet opened the box (after years...). Since this unit came from my employer, who has a metrology, and calibration group, I‘m betting on the bad cable, bad power, or fuse. Once I open it up ( hopefully in the next 2 months, I will post what I find out). My unit has the ovenized stall oscillator and the high voltage option. I’m hoping to use it as a calibration source.....just need to check it against a stable reference (I also have an HP 105A reference source).

Thanks again!

Hi all: I am in the process of troubleshooting a Tek AM503 current probe amplifier and am looking for the small SMD sized type of grabber clips. I have some of the larger Pomona types with the L-shaped grabber. This is a bit large to clip around densely populated leaded components. I did see the real Pomona SMD types, but at around $20 plus for single quantities, that is way too steep for my tiny hobby budget ( for my paying job..not an issue, as I recently purchased some of the Tek clips for their GHz rated probes for $500 a pack)..
I searched Amazon, but the clips I found were cheap made in you-know-where (isn’t everything made there...??).
And reputable ones were WAY out of my price range. I have some of the logic-analyzer type, but really do not want to cannibalizes any just to make grabbers for this project.
Any ideas appreciated!

Hi all,

I have a number of examples of the older style case HP gear (8640B, 8405A, and now a 3440A) that all lost their feet at some point before I got them. I know these feet are rather scarce, but I hold out hope to find some. Anyone here have some they'd be willing to part with? Feel free to message me offline and we'll negotiate fair compensation.

Thanks!

Sean

The logical step in any situation is to replace a failed component.? But when one relies 100% upon a mission critical part, without knowing that it failed, they can be subtly surprised if it had failed.

The presence of a fail-safe assembly can sometimes woo a few in to false security.

I'm sure that nearly everyone has grasped the concept that anything can fail.

Gregf

I should point out I have not attempted this as I had no reason to, why I am sharing this is that it appears to be an unusual exploit should you desire a more fine frequency control though not without its obvious draw backs. I am anticipating there might be people in this group who wouldn't recommend this, I haven't tried it and I certainly don't encourage others other than simply being a interesting discussion.

... Relying on super caps is not 100%.? I have found bad ones.
... It's better to be safe than always assume goodness.

I never assume goodness, hence my statement to always do a backup.

A backup should be done anyway as a matter of good care and feeding, even if not replacing the battery.

As long as I had a backup in hand, I would personally not worry about an external power connection.? It's more poking at the board with a soldering iron, now with wires in the way, and more time and opportunity for something to go wrong.

If the super-cap didn't hold, it should be replaced.? HP designed it onto the board for the sole purpose of easy battery replacement.

-mark

To put simply, take a function generator such as a HP 3325B, set the output to 0dBm at 10 Mhz, plug that into the reference input of the signal generator. Then if you want a frequency of 100 Mhz just dial that into the signal generator. If you desire more precision with the frequency than what the signal generator is capable of, just make very slight adjustments to the function frequency on the generator supplying the the reference 10 Mhz.

I would think this could work somewhat however it might not scale linear at the various frequencies set on the signal generator, and the phase noise would suffer. And to determine the actual frequency a frequency counter would be needed.

Hi,

If you do not hear the relays clicking, first thing to check is the
ribbon cable between the attenuator board and the A14 board. They are
notoriously bad, to the level that on one of my 3325A I replaced the
pin headers and the ribbon cables. The newer ones are ok, but the
older version which somewhat looks like a flatflex cable, they are
bad.
If that is not the case, then on some versions there is a fuse on the
power supply board, which fuses unregulated 15V power to the relays.
it is quite easy to blow, if accidentally shorting the separate cable
that is supplying it.

Otherwise follow the service manual of the troubleshooting and follow
the signal path.

Szabolcs

Randy Newman <randy.n.at.home@...> ezt írta (id?pont: 2020.
márc. 1., V, 2:30):

Relying on super caps is not 100%.? I have found bad ones.? It's better to be safe than always assume goodness.

Greg

Don,

If I’m not mistaken, HP part number 2110-0301 crosses to a Littelfuse part number 0275.125 under their Picofuse product brand.? This fuse was obsoleted in 2007 along with many others in this product line.? Some other Littelfuse part numbers that are compatible and still available are:

0251.125 – Picofuse II, 125V, 0.125A, very fast acting

0263.125 - Picofuse II, 250V, 0.125A, very fast acting

?

There are others but the remainder are time-lag or slow-blow types which are not recommended for inputs such as those found on test equipment.? You want rapid overload protection for the circuitry that lies behind the front panel connector.

?

If you Google the above part numbers you will find distributors that handle the fuses for prices much less than what HP/Agilent/Keysight will charge you for the very same device.

?

Greg

On Sun, Mar 1, 2020 at 12:01 PM, Nigel wrote:

In general terms I could never understand why the American electronics and radio industry, from hobby level all the way through to military, embraced these so universally as RF connectors, although I suspect cost would have been a significant factor.

What type of connector are you referring to? Apart from the fact that "RF phono" seems an oxymoron to me, I am not aware of HP widely using low-cost connectors. Are you talking about RCA/cinch connectors?

Raymond

What does it mean by Keysight qualified part?
Apparently the 34401-49321 part is listed this way and it won't let me purchase it.?
Thanxs?

I used Chrome and it seems to work, now I have to wait for verification?

The additional effort to attach an external power supply to keep the memory contents is really not needed.

In the referenced Assembly Repair manual there's a section on how to replace the A16A1BT1 (page 337).? The memory board has a super-cap which keeps the memory powered for up to 8 hours while you replace the battery.

The RTC will be reset when you remove the memory board.? Don't panic.? This is because the RTC is on the main board and get its power from the battery on the memory board.

But ALWAYS do a a paper backup of the constants anyway!? User data needs to be backed up via GPIB or an SRAM card.? I've been able to backup DLLs via GPIB, but have not been successful via an SRAM card (at least not for DLLs loaded by the EMC personality card).

If you do lose the memory for whatever reason, after the restoration procedure you can use the undocumented command "SERSET nnnn;" entered via GPIB or EXECUTE TITLE to restore the serial number (if you care about it being set).


You don't need to poke at memory for anything, but since it was mentioned, here are the GPIB commands for the 8590 series:

? MRDB <addr> - returns single byte in decimal
? MRD <addr> - returns single word in decimal
? MBRD <addr>,<count>? - returns a block of memory in binary

<addr> and <count> are in decimal.? The SRAM is 524288 (0x80000) bytes long and starts at 0xf80000.? It's a Motorola processor, making storage big-endian.? I/O is memory mapped, so there's a lot to explore outside the SRAM range.

For write, I found the commands MWRB, MWR, and MBWR.? No doubt these are the analogous operations for writing, but I did not experiment with them.

For example, the model number exists at 0xffbfee, 16760814 decimal, and is stored as decimal:

? $ spq MRD 16760814
? 8595

And after that, the next byte:

? $spq MRDB 16760816
? 69

69 is decimal for "E" --> "8595E".

Have fun!

-mark

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