Tektronix 422 losing intensity

[samcan]

My Type 422 Tektronix scope intensity knob needs to be near or at max clockwise to be able to have a trace.

Any suggestions on re-establishing full range intensity?
Do I need a new CRT?

[retiredcaps]

Re: Tektronix 422 losing intensity

I can't help you, but there are lots of Tek fans over at the eevblog.com forum. One person there, tekfan, as the name implies knows a lot about Tek scopes.

[multimeter]

Re: Tektronix 422 losing intensity

try cleaning the pot ,i had a freind had the same issue with an older scope,wouldnt show trace until it was fully clockwise,i cleaned it with contact cleaner and it worked fine after ,wasnt the same make as yours tho.

[Peter9DO]

Re: Tektronix 422 losing intensity

Hit it a couple times on the side!** It used to work with the old CRT TVs! lol!

**Do NOT under any circumstances take my advise! If you decide to beat the hell out of your scope I (Peter9Do) take no responsibility for the outcome, which I for see not to be beneficial to the scope or yourself. I will also not take any responsibility for any personal injury you may do to your (but not limited to) hand, arm, head, foot, leg, knee in the process of dropping a dime on that sucka @$$ O-scope! Keep the proceedings as peaceful as possible and if you must go the rout of bitter rage please video it and post it on YouTube (Please share link on BadCaps forum) like the rest of us would! Thank you!

[Peter9DO]

Re: Tektronix 422 losing intensity

Here is the service manual for the scope:



Just click the link on the bottom of the page that says "get manual".
Good luck!

-Peter

[tensorarc]

Re: Tektronix 422 losing intensity

Your posted a link to the Tektronix 422 service manual that is for serial No. 1-19,999, do you have a link for serial No.'s 20,000 and above? The two manuals are not the same. Serial's 20K and above do not use Nuvistors.

[eccerr0r]

Re: Tektronix 422 losing intensity

Usually the dimming is mostly irreversible and a new CRT is needed. About how many hours has it been used? (if the answer is "I don't know" assume tens of thousands of hours. Half life of regular CRTs are only around 15K hours!)

With the service manual you should try the CRT calibration to see if it helps a little, make sure all the pots are good, and at least see if the voltages are good. There are some internal adjustments that may help, but once those are at their limits... new CRT time.

There are some rejuvenators out there that may help the CRT for a few hundred hours but ultimately again a new CRT is needed.

One question is whether focus is still good? then perhaps it could be a different problem.