Products > Test Equipment

Tektronix 2235 repair thread

<< < (12/18) > >>

tautech:

--- Quote from: bd139 on March 07, 2019, 12:53:53 pm ---Possible. I might take the tube out and inspect it as well. Look for flashover. Wonder if it got gassy

--- End quote ---
This looks mint to me:



Gotta be control circuitry but maybe CRT socket pins could be cleaned, if for nought than to eliminate them.

bd139:
I did a quick video earlier of it.

This is in X-Y mode, deflection plates disconnected (to eliminate amps).

Brightness unstable, deflection is vertical (scope was on its edge)

https://youtu.be/Lo-WzwbXh1Q

David Hess:
A change in the acceleration voltage causes a change in deflection.

A dirty insulator or high voltage breakdown might cause it but would be difficult to track down.  Still, try examining the high voltage sections in a dark room and maybe it will be visible.  Or just scrub down and clean the high voltage parts of the board with distilled water.

Easier to test are the acceleration voltages and especially the primary side of the switching regulator since this design does not rely on secondary side regulation of the acceleration voltages.  I would make a careful measurement between the collector of Q939 and ground to see if it is jumping.  Maybe a part in the regulator circuit has developed flicker noise.

bd139:
Just a final update on this one. I managed to get hold of a later fully working 2235A so this 2235 is now relegated to parts mule status I'm afraid.

The 2235A does however have a terribly whiny power supply. This goes away after it has warmed up but it's a bit irritating for the first 5 minutes.

wasyoungonce:
Sounds like it needs new psi caps

Navigation

[0] Message Index

[#] Next page

[*] Previous page

There was an error while thanking
Thanking...
Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod