Tektronix 2465B ALL Test Pass but bot working properly - Page 1
Forum section: electronics / repair

author: RahmanID
author_rank: Contributor
timestamp: July 13, 2025, 10:50:16 am
content: I have 2465B- replace all caps (done)- also caps inside A5 Board (CPU)but still not working, I have read everything from page 1 to 79 on thread:https://www.eevblog.com/forum/testgear/tektronix-2465-repair-419753/but not found exact problem with my scope,the problem is. the CRT show many dots, (see attachments)

author: calibrationfixture
author_rank: Regular Contributor
timestamp: July 14, 2025, 06:21:00 am
content: Hi RahmanID,You must look at the Grid Bias. Some time ago I had to service a RM2465B (B057275) with no display. All Power Supply Voltages were fine. Adjusting the Grid Bias gives me your display. In my case with Error Codes (Test 05 Fail 44). With replacement of SMD Capacitors, R2013 (10K 0.1%) and thorough cleaning of the A5 Board the Scope was functioning normally again.Calibrationfixture

author: chilternview
author_rank: Frequent Contributor
timestamp: July 14, 2025, 09:50:00 am
content: The dots mean it's uncalibrated.You'll need to go through the calibration sequence or reprogram the NVM with a valid cal e.g. as in this threadhttps://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/25/

author: calibrationfixture
author_rank: Regular Contributor
timestamp: July 14, 2025, 12:14:29 pm
content: Hi to Both,Topic states ALL Test Pass. As his Display shows.Out of the Repair Notes of an Uncalibrated 2465BDM (H705638):A5 Jumper on CAL. .... between Scale Factors (Single Row)A5 Jumper on NO CAL? between Scale Factors (Single Row)Thus not 4 Rows.Calibrationfixture

author: Kwakerman
author_rank: Regular Contributor
timestamp: July 14, 2025, 12:16:55 pm
content: Adjust Grid Bias first (its in the service manual and adjusted under Cal 08 IIRC), don't think it is an actual Calibration issue as you have 'All Pass', if it were a Cal fault you would/should have a 'Test 04 Fail XX' on the CRT.

author: chilternview
author_rank: Frequent Contributor
timestamp: July 14, 2025, 12:38:21 pm
content: Well, maybe I'm mistaken, but I certainly got this after aborting a cal sequence on my 2465B - only two rows of dots though, between the display readout lettering. Successfully completing cal -> dots went away.

author: calibrationfixture
author_rank: Regular Contributor
timestamp: July 14, 2025, 12:42:03 pm
content: Hi to All,Same display and its solution:https://www.eevblog.com/forum/repair/tek-2465b-failed-with-strange-display/Calibrationfixture

author: RahmanID
author_rank: Contributor
timestamp: July 14, 2025, 04:32:12 pm
content: Quote from: calibrationfixture on July 14, 2025, 06:21:00 amThank you for answer, will try it.I forgot notice, the intent knob for trace not working (has no effect when knob rotate), but knob for focus and readout working fine.

author: calibrationfixture
author_rank: Regular Contributor
timestamp: July 19, 2025, 05:14:34 am
content: Hi RahmanID,I think this Thread (including a YouTube Video Link) is more to the point:https://www.eevblog.com/forum/testgear/tektronix-2465b-mystery-dots/msg3910736/#msg3910736There is a link to it in the other Post I mentioned.Success,Calibrationfixture