2465B oscilloscope on screen text positioning - Page 1
Forum section: electronics / beginners

author: nhopa
author_rank: Newbie
timestamp: November 10, 2013, 04:18:55 pm
content: Recently I purchased a Tektronix 2465B oscilloscope. The onscreen text has shifted slightly upward. How can I readjust the text's position? Thank you, Nhopa.

author: BravoV
author_rank: Super Contributor
timestamp: November 10, 2013, 04:52:50 pm
content: First thing, I'm not an expert on this scope, its just I've been reading alot on this scope's circuits that I somehow understand where those text circuit originated from.Look at the attached photo below for the A5 digital board, there are two adjustment pots pointed by red arrows, one is for centering text location vertically, the other one is for gain a.k.a. for setting the top & bottom border for the on screen text.Don't worry, these two pots will not screw out the scope's calibration, only for adjusting the ROM based generated text from the digital board to the vertical positions.Hope this helps.PS : Yes, the photo shows the A5 board up side down, and that two pots located at the corner, or near rear part of the scope.

author: Bryan
author_rank: Frequent Contributor
timestamp: November 10, 2013, 10:31:06 pm
content: I think I would follow the service manual. It may store some setting in the EEPROMCAL 07 - READOUT CENTERING AND GAINCheck/Adjust Readout Centering and Gain(R2918, R2931).Scroll to CAL 07.Press and release the upper TRIGGER COUPLINGswitch to initiate the routine.CHECK– Readout displays large 8 characters in thetop line and BWL characters in the bottom line.ADJUST– Readout Centering (R2918) and Gain(R2931) so characters remain just inside the graticulearea.Press and release the lower TRIGGER COUPLINGswitch.

author: nhopa
author_rank: Newbie
timestamp: November 11, 2013, 05:26:47 pm
content: Hi BravoV and Bryan:Thank you both for the quick response. Either way I will have to open the case for access to the pots or to the jumper. Since I purchased this scope I found a good article on the internet with step by step instructions on how to refurbish this scope. May this would be a good time to do just taht. I would like to know if someone sells a kit for that project. Most of the components to be replaced are capacitors and some diodes. Any thoughts on this matter. Thank you, Nhopa.Since my last post I took the cover off the scope and since the pots were right there I made a slight adjustment and the text now is vertically centered. I am member on other forums too but I think the smart people are on this forum. Thanks again for the fix.One more question, when I power up I get the "Test 04 fail 12" message. The seller told me not to worry, it has something to do with the "checksum", just push A/B Trig and the scope is ready to use. Should I be concerned?

author: GreyWoolfe
author_rank: Unknown
timestamp: November 12, 2013, 03:55:55 am
content: Download the service manual--http://physics.ucsd.edu/neurophysics/Manuals/Tektronix/2465%20Oscilloscope%20Manual.pdfand look at section 6. The error is with the EAROM bad checksum (bit 4 set). I couldn't get any additional information from doing a quick look. It could be as simple as needing a calibration, I don't know. Hopefully, the really smart people on the forum can provide additional information.Tom, NW0LF