Jim Yanik wrote in message ...
"bg" wrote in :


Jim Yanik wrote in message ...
"bg" wrote in :

Both channels on the verticle front end are damaged. One dual FET
follower is a definite (Q1297). It is tek part number 151-1090-00. I
haven't seen one yet using google. Is there a replacement or two
discretes out there that will work?

They would have to be matched,else you get an offset.

check this out;
http://www.sphere.bc.ca/test/tek-parts/tekparts2.html
it appears they have some 151-1090's for sale.
they also cross ref to a "2N5911 family".



the 155-0078-xx is used in a lot of different scopes,several 7000 series
plug-ins,too.

--
Jim Yanik
jyanik
at
kua.net
Thanks Jim. I had already been to that site and didn't see it the first
time, even with my glasses on!
Offset is the issue I am having.
bg



I've seen the input BNC connector cause DC offsets!
seems it absorbs contaminants and becomes a weak "battery".


--
Jim Yanik
jyanik
at
kua.net

I replaced the ch1 connector, but connected a power connector backwards. It
blew one of the dual FETS and the other seems to have a leakage problem.
There is DC on the gate where the attenuator output connects. The one meg
resistor in the attenuator output is not low enough to pull the gate to
zero. Out of the circuit, I don't see anything wrong with the fet.
BTW , you are a great resource for these tek products, thanks.