Recapping Tektronix 2235 PSU

[redwire]

Re: Recapping Tektronix 2235 PSU

The 2235 is old school pcb layout (tape) and the 2235a is the jump to CAD.
The 2235 beats the 2235a for some reason -
In tech college we had labs full of new 2235a's and after a few months many of them were terrible - the triggering went bad. Prof said it was a varactor diode somewhere but I have not dug into that or if it just needs calibration. Many service bulletins as well on the a's.

My 2235 is so painless to use that it is my go-to for serious analog stuff. Compared to my 2235a which is a dog and I have yet to troubleshoot the trigger section to see why it does not work well.

[ls120nz]

Re: Recapping Tektronix 2235 PSU

Hi I'm new here and have been given a Tektronix 2235 that the power supply has a problem.. i have not opened and checked yet but have a form from the company that looked at it saying its the psu and that's it.. my question is where do i start and is there a list of the tech upgrades that were done over the versions that i can do while fixing this.. i do have a 30hnz scope as well it's a Gould OS1100 dual trace with delay that's working fine..

[redwire]

Re: Recapping Tektronix 2235 PSU

I posted a Rev. 2 spreadsheet list of the 2235/2235B capacitors in #17.
I would take it apart and look at the caps, some of them are known to just croak after 40 years. What I did is first replace the PSU caps spend the $25. If the scope is dead it can be the mosfet that failed.
It's a terrific analog scope and worth the repair.

The upgrade list depends on serial number and I have never seen a good summary except in one service manual. I've just left mine alone aside from the focus resistors that would overheat.

[ls120nz]

Re: Recapping Tektronix 2235 PSU

thanks i'll look over the sheet.. i have down loaded it now.. i'll let you know how i got but i think the 4 leg cap is December before stock is back in...

Regards
David