Hi Jean-Marc,
I happen to be working on a 7B53N as well (mine doesn't trigger). I purchased a scan of the service manual from Artek Manuals. It has the correct schematics, etc., and might be well worth getting one of those scans from Dave.
I wish Tektronix had included some expected waveforms at the TPs and typical voltage values for pertinent points in that manual but, apparently, they did not so troubleshooting is a still a bit challenging.
Thanks,
Barry - N4BUQ
toggle quoted message
Show quoted text
----- Original Message -----
From: "Jean-Marc Imbert" <jmimbert@...>
To: "tekscopes" <[email protected]>
Sent: Friday, December 10, 2021 8:57:33 AM
Subject: [TekScopes] 7B53N sweep repair
Hello all from the great Tekscopes group,
My 7B53N has SN B051276 and the sweep board doesn't use the components showed in
the 7B52 service manual. It takes from the 7B53A because of the central
component (sweep control IC) which is 155-0049-(00). But it's not at all like
the 7B53A either and the schematics part numbering is entirely different
anyway.
So it is very difficult to follow the horizontal section flow (loop) without an
actual schematics and layout.
The 7B53N worked very well and suddenly wouldn't start sweeping (vert. defl. ok
on a 7633).
The trigger triggers OK but sticks lit. Trigger TDs CR470 and 475 arm and fire
OK.
The X amp works fine driven by a 7CT1N.
The trace is showing a very weak unblanked vertical (a non horizontally swept
sine) far left (2 virtual screen widths ? ) off the screen if recovered with
the 7B53N X position.
I am not sure whether the -15 V which reads -12.65 V after R128 (7B52 voltage
distribution - Schem. n¡ã10) is a problem.
I'd like to follow up with Holdoff and Unblank functions debug.
Does somebody please know a pdf schematics source for the version of the 7B53N
with 155-049-00 sweep IC ? Or could send a scan of the sweep board service
pages ?
Salutations.
Jean-Marc
ps excellent extender from John Griessen allows some repairs which would be a
chore without ! Thanks again John !
