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| John Larkin... |
 Posted: Mon Nov 02, 2009 9:50 pm |
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On Mon, 02 Nov 2009 17:33:48 +0000, ChrisQ <meru at (no spam) devnull.com> wrote:
[quote]John Larkin wrote:
On Mon, 02 Nov 2009 06:32:36 -0500, JW <none at (no spam) dev.null> wrote:
On Fri, 30 Oct 2009 16:26:43 -0700 John Larkin
jjlarkin at (no spam) highNOTlandTHIStechnologyPART.com> wrote in Message id:
8esme5lhfqjpuab990t4foat0jsq9mp4ng at (no spam) 4ax.com>:
I just got an SD-30 (50 GHz) sampling head for $1500. There's tons of
cheap Tek gear on the market now.
WHAT! You didn't negotiate, or they wouldn't budge? ;)
I made them an offer they shouldn't have refused, namely to tell them
how to fix a bunch of their broken sampling gear in exchange for a
decent price break. They didn't go for it.
Fine; that leaves more broken gear on the market that I can buy cheap
and fix.
John
One thing that you might find relevant is that faults sometimes just go
away. I bought a 54112 scope on Ebay for 40 ukp last year, which had
memory and module post test failures. The first thing was to remove all
the boards, clean the edge connectors etc and reseat, but the module
post still failed. I left the thing on for a week solid, then repowered
up and while the post test passed, one of the 4 channels was quite
noisy. Left it running for a few more days and the noise went away and
it's been good since. Even ran the calibration procedure fine as well.
Thinking about it, the failure mode seems to be one of damp getting into
the ic packages and causing leakage. A lot of the older test gear may
have been left in unheated stores for many years prior to disposal and a
thorough baking seems to be quite good for them. Have recovered a couple
of other instruments this way as well...
Regards,
Chris
[/quote]
These Tek 11801-type scopes sometimes throw an error on powerup and
while running. Many of them just go away.
John |
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| JW... |
| Posted: Tue Nov 03, 2009 10:57 am |
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On Mon, 02 Nov 2009 07:23:18 -0800 John Larkin
<jjlarkin at (no spam) highNOTlandTHIStechnologyPART.com> wrote in Message id:
<v6ute592njq76re6uq3adhvshbpbep1gb6 at (no spam) 4ax.com>:
[quote]On Mon, 02 Nov 2009 06:32:36 -0500, JW <none at (no spam) dev.null> wrote:
On Fri, 30 Oct 2009 16:26:43 -0700 John Larkin
jjlarkin at (no spam) highNOTlandTHIStechnologyPART.com> wrote in Message id:
8esme5lhfqjpuab990t4foat0jsq9mp4ng at (no spam) 4ax.com>:
I just got an SD-30 (50 GHz) sampling head for $1500. There's tons of
cheap Tek gear on the market now.
WHAT! You didn't negotiate, or they wouldn't budge? ;)
I made them an offer they shouldn't have refused, namely to tell them
how to fix a bunch of their broken sampling gear in exchange for a
decent price break.
They didn't go for it.
[/quote]
In all fairness I already suspected the 93c46 clone and replace might
work, but they didn't even *ask* me. I'm the mushroom that works in the
basement. (Keep me in the dark and feed me shit)
We've only got 1 sampling head in the "graveyard" right now. It's a 50GHz
SD-32. It's not a potential for EEPROM replacement as it causes the 11801
to fail with a TXXXX timing error on power up. Perhaps it's bus related;
even a pinout on these things might be helpful. |
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| ChrisQ... |
| Posted: Tue Nov 03, 2009 4:37 pm |
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Guest
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John Larkin wrote:
[quote]
These Tek 11801-type scopes sometimes throw an error on powerup and
while running. Many of them just go away.
John
[/quote]
If they have microprocessor control, another thing to watch out for is
the static ram chips in some early micro controlled test gear. I had
some hard fail on a Fluke calibrator which was confirmed by swapping the
2 ram chips round between sockets. The micro was locking up on startup,
so a ram failure in a different area resulted in a different set of leds
left lit on the front panel.
Processor chips fail as well, as does cd4xxx cmos, but ttl seems
remarkably resilient...
Regards,
Chris |
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