Re: More details TEK 468 with no CH1/CH2/ALT buttons working

Fabio Trevisan
 

Hello Sam,
I have already sent a message in PM to you (in portuguese, easier)
regarding that, but it may be helpful to comment here and get some advice
from the group as well on my assumptions...
From what I could see, on the 468, U310 and U466 are microprocessor
controlled (by means of signals /MODE and /VSM, coming out of U358 that
decodes I/O commands from the uP) so, the test that you did just confirm
that the vertical switching logic is working (U408 and U409) but it doesn't
tell much about U310 or U466 because both depend on the uP action to
perform their functions.

@Group...
=>Am I correct in that the 468 microprocessor controls part of its
operating panel functions and that it can't be used in full if the
microprocessor is inop?...
Or U310 and U466 are just means for the uP to "tap" into the vertical
scope's control functions being transparently and independently read and
translated by U466 and stored on U310.

=>Being the 465B an analog brother to the 468, is it possible to
"down-convert" the 468 to work without the microprocessor, like a 465B? Or
there would be parts missing?

=> I was trying to study the schematics of the 465B, but apparently the
page of Diagram <4> is missing from every manual I could find. Is this
page available in separate somewhere?

Rgrds,

Fabio



2017-07-05 15:56 GMT-03:00 Samuel Rocha py1dkw@... [TekScopes] <
TekScopes@...>:




Hi Group,
I would like to give more details as I had disassembled and checked some
points as follows:

The scope has no difference pushing buttons CH1/CH2/ALT/ADD, it is always
on ADD, showing trigger waveform too.

In the vertical Switiching Logic board, connnected to U310 ther is a plug
P306. Well all the pins were at 1,8v regarding of the button pushed, so I
connected to ground pins 1 and 2 of the P306, this way the scope only shows
ch1 and ch2.
So, I suppose ther is a problem in U310 or U466, is that correct?
Another problem is that the base time control does not work at 12
positions, the ones which have the greater base time values before x-y
position, I suspect of C435, 1,5 uF, but I did not check it already.
Seems a lot of trouble for just only one instrument!
Thanks for any ideas and suggestions!
Regards to all,Sam



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