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Keysight 34465A reliability

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skander36:
It is very possible that this section to be involved in overvoltage protection. I don't understand what is the role of J110 jumper.
I want to ask the owners of the KS34465A  what is happened when touch the red wire when the DMM is on DCV mode. A relay is clicking every time when I touch the red wire when is on DCV. None of my DMM (nor Keythely nor Siglent) behave like this.

AVGresponding:

--- Quote from: tooki on April 24, 2022, 03:23:06 pm ---
--- Quote from: AVGresponding on April 23, 2022, 04:12:57 pm ---Yes, I understand; it's more practical to create a mod-board than to re-spin the main one, usually.

--- End quote ---
Do you understand, though?? This isn't a mod board as such. A mod board is commonly understood to mean a daughtercard made to implement a bodge to correct an error on the main PCB, rather than making a new main PCB.

As I explained above, early versions of the board had this part of the circuit on the main PCB. Then on this later version, the main board was respun to move that part of the circuit onto a daughtercard.

This isn't a cost-saving measure, as it's more expensive in every way: the added engineering cost, a respun main PCB, a new daughtercard, and the extra labor to solder the daughtercard onto the main PCB.

--- End quote ---

Even by your own definition, it clearly is a mod board, as the new main board is (what appears to be) not a respin but a new "universal" design, intended to be used in multiple models, but which lacks the onboard capability for these necessary components in a 34465.




--- Quote from: tooki on April 24, 2022, 03:27:35 pm ---
--- Quote from: AVGresponding on April 23, 2022, 02:56:53 pm ---I know, but that still doesn't make it ok

--- End quote ---
As wraper said, cleaning in situ could get flux residue into places it shouldn't be. And with the two boards soldered together, cleaning becomes much more difficult.

So you'd be adding a cleaning step with no advantage, but plenty of risk.

I guess you don't open many devices. If you did, you'd have noticed the flux residue found in all sorts of equipment, from consumer electronics to IT to test gear to appliances.

--- End quote ---

Please leave ad hominem attacks where they belong; on the editing room floor (inside your head).

Difficult is not impossible, and the risk is a balance between existing potential for harm, post-cleaning potential for harm, and the additional costs of either having unwanted warranty claims (something we can only speculate about as Keysight will certainly not release such commercially sensitive information), or additional costs of cleaning plus potential unwanted warranty cost as a result of more harm being done than good.

Yes, I understand very well, thankyou, nevertheless it's cosmetically unattractive, and in an instrument where I expect seriously anal levels of cleanliness, it does not sit well.

tooki:

--- Quote from: AVGresponding on April 24, 2022, 07:33:36 pm ---
--- Quote from: tooki on April 24, 2022, 03:23:06 pm ---
--- Quote from: AVGresponding on April 23, 2022, 04:12:57 pm ---Yes, I understand; it's more practical to create a mod-board than to re-spin the main one, usually.

--- End quote ---
Do you understand, though?? This isn't a mod board as such. A mod board is commonly understood to mean a daughtercard made to implement a bodge to correct an error on the main PCB, rather than making a new main PCB.

As I explained above, early versions of the board had this part of the circuit on the main PCB. Then on this later version, the main board was respun to move that part of the circuit onto a daughtercard.

This isn't a cost-saving measure, as it's more expensive in every way: the added engineering cost, a respun main PCB, a new daughtercard, and the extra labor to solder the daughtercard onto the main PCB.

--- End quote ---

Even by your own definition, it clearly is a mod board

--- End quote ---
Absolutely not.

A mod board is a patch made applied after the fact to an existing part to correct an error discovered after manufacturing, so that you don’t have to trash the existing part. They DID redo the existing part, and this board was designed to be there from the beginning of this redesign.


--- Quote from: AVGresponding on April 24, 2022, 07:33:36 pm ---as the new main board is (what appears to be) not a respin but a new "universal" design, intended to be used in multiple models, but which lacks the onboard capability for these necessary components in a 34465.[/color][/size][/b]

--- End quote ---

Since we don’t know for sure why those parts were moved off the main board, we certainly can’t conclude that it’s because of making it a universal design. (I frankly doubt that it has to do with reusing the board in multiple models: it’d almost certainly be cheaper to make different boards than to have the added labor to solder on a daughterboard. Remember that that’s just one person’s random guess, not even the result of circuit analysis.)

Also, by what logic is a new board design not a board re-spin?  :-DD


--- Quote from: AVGresponding on April 24, 2022, 07:33:36 pm ---

--- Quote from: tooki on April 24, 2022, 03:27:35 pm ---
--- Quote from: AVGresponding on April 23, 2022, 02:56:53 pm ---I know, but that still doesn't make it ok

--- End quote ---
As wraper said, cleaning in situ could get flux residue into places it shouldn't be. And with the two boards soldered together, cleaning becomes much more difficult.

So you'd be adding a cleaning step with no advantage, but plenty of risk.

I guess you don't open many devices. If you did, you'd have noticed the flux residue found in all sorts of equipment, from consumer electronics to IT to test gear to appliances.

--- End quote ---

Please leave ad hominem attacks where they belong; on the editing room floor (inside your head).

Difficult is not impossible, and the risk is a balance between existing potential for harm, post-cleaning potential for harm, and the additional costs of either having unwanted warranty claims (something we can only speculate about as Keysight will certainly not release such commercially sensitive information), or additional costs of cleaning plus potential unwanted warranty cost as a result of more harm being done than good.

Yes, I understand very well, thankyou, nevertheless it's cosmetically unattractive, and in an instrument where I expect seriously anal levels of cleanliness, it does not sit well.

--- End quote ---
An observation isn’t an ad hominem attack.

I said that I guess you don’t open many devices, and that still remains a reasonable assumption, since your surprise at a bit of flux residue in a place where it clearly does no harm (because if it did do harm there, they’d remove it!) would have been tempered by seeing it in device after device. (Either that, or you have opened lots of devices but just haven’t been observant.)

Kleinstein:
The added extra board looks like it not only contains some parts, but also acts as a bridge to bring one of the signals from one side to the others. It very much looks like the extra PCB was planed togehter with the updated main board.

A reason for the new board could have been the problem they had with the high voltage rating, though the rumors were that this was from the relay ratings.
With the input signals routing needs quite some space for isolation and they may have just run out of board space in that corner and did not like a full redesign. The protection part on a separate board to simplify repairs may be an extra bonus.

The 34460, 34461, 34465 and 34470 are not that different. A combined board would make sense and should not take up more space. It should be mainly be a few parts missing with the 2 low end versions and maybe 1 or 2 bridges in the amps part to replace a relay or shunt.

AVGresponding:

--- Quote from: tooki on April 24, 2022, 10:44:17 pm ---Absolutely not.

A mod board is a patch made applied after the fact to an existing part to correct an error discovered after manufacturing, so that you don’t have to trash the existing part. They DID redo the existing part, and this board was designed to be there from the beginning of this redesign.
--- End quote ---

You don't think it's an error to design a board that needs to be changed to move some parts to a daughter-board? There is a design error here, whether in the original that required a revision, or in the revision that could not be made to work without the extra expense.




--- Quote from: tooki on April 24, 2022, 10:44:17 pm ---Since we don’t know for sure why those parts were moved off the main board, we certainly can’t conclude that it’s because of making it a universal design. (I frankly doubt that it has to do with reusing the board in multiple models: it’d almost certainly be cheaper to make different boards than to have the added labor to solder on a daughterboard. Remember that that’s just one person’s random guess, not even the result of circuit analysis.)

Also, by what logic is a new board design not a board re-spin?  :-DD
--- End quote ---

Because it is not a new board intended only for the 34465, it is intended (by fairly obvious implication) to be used at least in the entire 3446X family, and as some have speculated in the 34470 as well.




--- Quote from: tooki on April 24, 2022, 10:44:17 pm ---An observation isn’t an ad hominem attack.

I said that I guess you don’t open many devices, and that still remains a reasonable assumption, since your surprise at a bit of flux residue in a place where it clearly does no harm (because if it did do harm there, they’d remove it!) would have been tempered by seeing it in device after device. (Either that, or you have opened lots of devices but just haven’t been observant.)

--- End quote ---

It isn't an observation, it's a subjective opinion expressed in a way to attempt to belittle the subject; you imply I am less experienced than you and therefore my opinion is of less value than yours. And you just did it again.


You also make an unwarranted assumption; that if the flux residue could be harmful, they would remove it. I explained in my last post why this is not necessarily so, and I can assure you I have the relevant experience to make the guesses that I did as to why they did not clean up afterwards.

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