Vert. pos. fix for Tek 2235 oscilloscope?

[Robert Martin]

I have a Tektronix model 2235 dual trace oscilloscope.

Both traces will not adjust vertically below the upper quarter of the
CRT. IOW they stop about 1/3 of the way to the bottom of the screen.

Can anyone with experience in this area please advise where to look
for the fault, or perhaps recalibration.

Since both traces are affected, it would seem related to the
deflection voltage.

Robert Martin

 

[budgie]

On Thu, 08 Apr 2004 17:43:18 +1000, Robert Martin <rmartin@iprimus.com.au>
wrote:

I have a Tektronix model 2235 dual trace oscilloscope.

Both traces will not adjust vertically below the upper quarter of the
CRT. IOW they stop about 1/3 of the way to the bottom of the screen.

Does it look like this one:

http://cgi.ebay.com.au/ws/eBayISAPI.dll?ViewItem&item=3808241722&category=1502

 

[Jim Yanik]

Robert Martin <rmartin@iprimus.com.au> wrote in
news:8vv970h5pjra2q2ikl0c1mlbb80613ca65@4ax.com:

I have a Tektronix model 2235 dual trace oscilloscope.

Both traces will not adjust vertically below the upper quarter of the
CRT. IOW they stop about 1/3 of the way to the bottom of the screen.

Can anyone with experience in this area please advise where to look
for the fault, or perhaps recalibration.

Since both traces are affected, it would seem related to the
deflection voltage.

Robert Martin

Check for open resistors in the vertical output circuit.IIRC,there were
some metal film resistors that changed value and eventually opened.The PCB
may also be discolored in that area from the heat. You may want to space
the new resistors a bit off the PCB to allow more air to circulate around
them.

--
Jim Yanik
jyanik-at-kua.net

 

[Andrew VK3BFA]

budgie <me@privacy.net> wrote in message news:<spja7053pb4use4fbh2etb7ua3emgctsvg@4ax.com>...

On Thu, 08 Apr 2004 17:43:18 +1000, Robert Martin <rmartin@iprimus.com.au
wrote:

I have a Tektronix model 2235 dual trace oscilloscope.

Both traces will not adjust vertically below the upper quarter of the
CRT. IOW they stop about 1/3 of the way to the bottom of the screen.

Does it look like this one:

http://cgi.ebay.com.au/ws/eBayISAPI.dll?ViewItem&item=3808241722&category=1502

Hey Budgie,
yeh, I thought that when I read the post question - thought about
bidding, but have enuff dead cros here already - and without the
manual, its going to be a bit difficult to service - still, nice CRO -
one can dream! - Trying to dispose of surplus stuff I am never going
to use (ha ha) so thats how I found the reference you mention....
Andrew