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Andy Cuffe Andy Cuffe is offline
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Default Tektronix TDS-744A SPC fails

Good news, replacing the relays appears to have cured the SPC problem.
Half of the old relays had an ohm or more of resistance, so it's no
surprise it was having problems.

Replacing the relays was fairly easy, but you'll need a good soldering
station with a long tip. The attenuators are ceramic hybrids, so I
used silver bearing solder just to be on the safe side.

I'm still looking for a CRT or two, if anyone has one left over from
an LCD upgrade, or parted out scope.

I will post back if I find the cal software.

One other question I have is about the TV trigger board (option 05).
My TDS544A has this, and I would like to move it to the TDS744A. I
already built new power ribbon cables and added the second connector
to the bus board. The TV trigger option shows up in the 744 and
passes the self tests, but the trigger level appears to be off. It
will only trigger when the trace is adjusted so that it's cut off at
the top of the screen. I suspect the board is either incompatible, or
that there is a calibration for the TV trigger level that needs to be

Does anyone know if any calibration is required after adding TV
trigger? Did Tektronix even allow you to add option 05?