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Re: HP 16500C looking for logic analyser boards that are functional

 

Looking at this from the point of view of making PC boards:

Corrosion on the surface kills one track.? That can be cured several ways and rather easily.

If corrosion covers a via, or a lead for a part, then life can be more complicated.

The board manufacturing process makes what's effectively an eyelet between the top and bottom layers.? The inner layers have their own eyelet (effectively).? When the board is assembled, the plating through process connects all these layers with the hole plating.

Corrosion can break this bond between layers.? To fix this, you must know where the inner layers (if any) connect.? That can be a problem unless you have a working board (and can trace it) or a schematic.

Harvey

On 11/16/2023 5:53 PM, Damien Towning wrote:
Thanks. I did find an article on fixing these boards buti it was a slightly different revision of the board. I've ordered up a decent scope so I can see the tracks better. I wonder if anyone can give me some details about the vias. The problems I have identified appear not to be with the hollow via type pins that go all the way through ( which have some sort of protective coating on them ) but with the kind that appear to join pads together. From the article I read they apparently have solder in them that can be sucked out but the ones on this board seem like they are solid. Anybody that has any insight in to doing this repair I would be interested to hear from.

On Thu, Nov 16, 2023 at 5:57?AM Mark Litwack <mlitwack@...> wrote:

Hi Damien,

There are no schematics available that I've ever seen.? And I
don't know of any analysis cards that don't have this problem to
some extent.? All the analysis cards I've seen have components on
the bottom, and therefore the plastic runners to "protect" them
from getting raked off.

You don't say what country you're in, but right now on ebay there
are two 16557D cards for sale in the USA for USD$49.95 each (+
shipping) in "Used" condition, which means they are claimed as
working by the seller.? If you get them and they don't work, you
can return them as "Not as Described", whether the seller accepts
returns or not.? For the ones I see (item #305031279984), the
seller accepts returns anyway.

That's inexpensive for these cards, and a factor may be that they
don't have cables, but presumably you don't need those anyway.?
What do you have to lose.

You could also try buying one, and if it works use it as a
comparison to fix yours.? It's much easier to fix these corroded
cards if you can compare to a working one.

Another tack is if you know someone with a 16700 mainframe, you
can plug in your 16557D cards and turn on some fairly verbose
debugging during self-test which may lead you to the problem.? I'm
not familiar enough with the 16500C to know if it has something
similar.? Maybe someone else can comment on its debugging
capabilities.

-mark


--
Damien Towning
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