mike wrote in news:BZTzj.11258$C1.7871@trnddc07:

JW wrote:
On Wed, 05 Mar 2008 21:07:20 GMT mike wrote in
Message id: cYDzj.15491$e_.6150@trnddc03:

JW wrote:
Hello all,

I have a TDS540A that was failing the acquisition board on it's
power-on self test. This unit had the problem where the small
electrolytics were leaking all over the board. After re-capping and
cleaning the entire unit, it now passes the self test, but CH3 is
completely dead. I probably should have done a preliminary
functional check first, ah well... Anyway, probing the input on the
(unknown) PLCC device U1200 shows that the input of the chip is
permanently biased at about -1VDC no matter what the input to CH3
is. Swapping the coax output from the attenuator board from another
channel yields the same result, so I'm pretty sure that U1200 is
the culprit. Unfortunately, I cannot determine what this part is -
it has a heatsink epoxied to the top of it, and I'm afraid of doing
more damage by trying to break the thing off. I know that Tek never
released schematics for this unit, but am hoping someone might know
what the chip is. Thanks for any help!
It's extremely difficult for people to help you if you don't include
a valid email address.

Hello,

Why? All I'm looking for is what the part # of a chip is. Follow-ups
to Usenet posts should be on Usenet, not email. I very rarely use a
valid email address, as I hate spam.

The chip part number is 155-0378-xx.
My bad.
I thought you actually wanted help fixing the scope.

As all you need is the part number, I'll go back to sleep.
Sorry for the mistake.
I'll endeavor to abide by the usenet posting rules.
mike

FYI,a 155-xxxx-xx is a TEK-made IC,out of production and no longer stocked
by TEK.

--
Jim Yanik
jyanik
at
kua.net