TDS544A with strange display #photo-notice


durechenew@...
 

Hello gentlemen,

My first post here, but I've been looking for information on this site for a long while.
Some 8 years ago I bought A TDS544A with normal caps issue; that was solved (removed all old caps, cleaned and replaced caps on all boards, repairing some traces). In the end the scope started to work fairly normal but some exceptions apply here.
Whenever there is a white patch on the right side of the screen (after pressing Vertical Menu, for example), there is a row of horizontal... lets call that bands, starting on the left of the screen, diminishing toward the right (see attached pictures).
These are not of constant length (visible from pictures); wild guess is that at the end of white patch (each line) there is a signal that changes (maybe from 1 to 0, or opposite) that triggers something like a sample and hold which allows dots to be displayed for a while during the next line (only on blue). No white patch at the right, no bands of blue at the left.
VGA output at the back of the scope shows normal (no such bands of blue).
Using a 2235 I tried to see some signals, mostly at J5, J62 (and synchro signals at J18), but that scope is not good enough to see specific lines while synchronized on frame signal.
I've seen some posts that tell me there are people around that know much more than necessary to give me some guidance where to look (and what to look for, in fact).
It maybe related, or not: it seems I cannot convince the scope to go to Auto (in Acquisition) after selecting Single Shot; the only way (i may be wrong in that is the only way) to see it running again is by selecting Autoset.
I would expect a lot of questions, don't keep anything back...

TT

P.S. Not sure why there is no menu at the top of the post, where you can click to add a picture, or format text.. I put a new post to tek500 and it was no issue to upload. What did I do wrong here?

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