Tektronix 434 s/n below 500000 faulty ps.

[johnmcgivern]

                    [attachment=15730]

Messed up forgot to put pics in last post tried to edit to add pics could not find attachments having fun.


Yes Craig I read the procedure, tried again just cannot get stable triggering from test points on 434.

Used different settings as you suggested was better but still flashing and walking slowly
See Pics 484, 485.
Generator in pic. sine and square nice and stable. bnc to 4mm plugs.
Other pics are waveform 1 section 11.
I have pointed out some caps can you enlighten me and what to use as replacements if faulty in future. Never seen caps like that all new to me.
So many different points of view for caps.
If the photos of waveform1 are ok let me know please and i'll attempt to do the rest.

[Craig]

You seem to have triggering set to auto. That should be OK, but try manually triggering instead.

[Refugee]

There should be a set-up procedure in the calibration section of the manual for the DC offsets in the Y-amps.

[Craig]

This is a pretty basic scope - the only DC offset/balance adjustment are the Y1 and Y2 trimmers on the front panel, looking at the adjustment procedure and schematics.

Craig

[johnmcgivern]

Tried free run using Timebase cal tried every setting no joy.
The actual signal looks similar to waveform but flickering.
Tried two balance screws exercised them noted positions little better it's just two pots for calibration.
Why would altering attenuation on y1&y2 interfere with these pots?
At least I learning about this scope.

[Craig]

I have no idea why you cannot get a stable trace, John. I guess I'm spoiled with my stable of Tek scopes, which trigger really easily with a rock steady trace.

If I still lived in Newcastle I'd come up and give a hand. But it is one hell of a trek from Oxford!

[johnmcgivern]

Craig will have another go today.
Many thanks.

[johnmcgivern]

[attachment=15748][attachment=15747][attachment=15746][attachment=15745][attachment=15744][attachment=15743][attachment=15742][attachment=15741][attachment=15740][attachment=15739]Hi Craig please find attachments that may explain whats happening.
These voltages are taken at P141 on sheet 12 storage.
They are at the best resolution I could achieve.
See pics.
Regards, John.
Craig for some reason I could not attach any more pics.
I have some more pics that explain what all pics are about will send in next post.
John

[johnmcgivern]

        These are other pics 508 should be read first.
Hope this helps if not just let me know.
John.

Sorry Craig, just noticed the jpg number of pic is not on attachment if you go through lowest to highest attachment number it should make sense.
Apart from the last attachment read this note first.

[Craig]

Your power supply is OK, voltages look good, and ripple is OK too given that it is a switching supply - looks like about 30kHz.

Your problem of bright trace that does not respond to the brightness control points you at the CRT circuit, not the storage circuit.