Re: New Member Dead 7704

 

Your knowledge of soldering and a DVOM isn't going to help you to understand
an oscilloscope. Get a copy of "The XYZs of Oscilloscopes" and read it
thoroughly before doing anything else.

You can download it here
http://info.tek.com/rs/584-WPH-840/images/XYZs-of-Oscilloscopes_03W_8605_7.p
df

From your YouTube video it appears you are just randomly turning knobs and
buttons. Read the section of the 7704 manual called "First Time Operation"
and set the scope and plugins up accordingly. You will need a BNC to BNC
cable to connect the vertical plugin to the calibrator.

Now each time you start the scope you will be in a known good state that
should result (when all is finally OK with the scope) in a square wave
waveform on the CRT.

Once you have the cable you need and you have set the scope up properly
according to the First Time Operation instructions take a picture or a
YouTube video of what happens on the CRT. Also take a picture of the entire
front of the scope so we can verify it is setup properly.

Never mind about the readout. That is a minor problem for now. Getting a
good display is your big problem. After seeing the pictures I don't think
swapping the 7B53 over to a vertical slot will tell us anything more.

Dennis Tillman W7PF

-----Original Message-----
From: TekScopes@... [mailto:TekScopes@...]
Sent: Thursday, January 05, 2017 9:31 AM
To: TekScopes@...
Subject: [TekScopes] Re: New Member Dead 7704

I have swapped the plugins around in their respective A/B slots but I
haven't tried swapping them from horizontal/vertical slots. I have wiggle
tested the plugins to see if bad contacts might be causing problems.
I tried wiggling what I think are the 10 number chips on the display board
as one or two of the characters seem to flicker intermittently.
What I did made no difference.
I'll give your suggestion a try.
The display works very intermittently and usually, the only way to see
anything on screen is with the beam finder.
I tried to pull a square wave off my handheld while the 7704 was "working"
but got this:

https://groups.yahoo.com/neo/groups/TekScopes/photos/photostream/lightbox/46
2709026?orderBy=mtime&sortOrder=desc&photoFilter=ALL#zax/462709026
https://groups.yahoo.com/neo/groups/TekScopes/photos/photostream/lightbox/46
2709026?orderBy=mtime&sortOrder=desc&photoFilter=ALL#zax/462709026


I downloaded the generic troubleshooting guide and the 7704 operating
manual.

I haven't found the manuals for my plugins yet.


The other time plugin I accidentally bought ( ) should arrive today.
I'll be able to switch back and forth for comparison.
I'll post results later.


It would probably help if I knew something about electronics, other then
having excellent unsoldering/soldering skills and being able to read a DVOM!
I'm pretty sure that everything has to actually hit the screen of the CRT
before I can troubleshoot the rest of the scope.
Again, the boards inside look very clean, not stinky and nothing I can see
is burned or exploded.
I haven't touched anything with DVOM or scope as I wouldn't know what I was
looking at anyway.
If you guys want me to check something or try swapping something around,
let me know.
I'll post back with pics, videos or values....whatever you ask for.
I've got good hands but I'm a monkey with a Tek 7704.








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Posted by: volvoboy242@...
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