Tektronix 2245A Flickering Issue - Page 1
Forum section: electronics / repair

author: verm1n
author_rank: Newbie
timestamp: February 22, 2016, 03:56:12 pm
content: Hello I just received my first oscilloscope(Tektronix 2245A) in the mail. On paper, it is pretty much everything I want from a scope. The problem is, i guess there were some shipping issues: for one, it seems that the components behind the front panel have sort of slid back, so aside from the buttons and the larger pots, nothing is responsive - once I get my hands on the torx screwdriver I need, I don't think this will be an issue.What I am more worried about is a flickering issue that occurs on all screens except for the setup menu. Should I return this oscilloscope, or would this be something that is not too difficult to fix? Both the OSD and the Trace, flicker btw.Much Appreciated

author: SAUL BRITTO
author_rank: Frequent Contributor
timestamp: February 22, 2016, 08:13:22 pm
content: Firt of all Adjust: intensity,H position,probe compensation

author: SAUL BRITTO
author_rank: Frequent Contributor
timestamp: February 22, 2016, 08:14:51 pm
content: Compare the same signal at the two channels.

author: SAUL BRITTO
author_rank: Frequent Contributor
timestamp: February 22, 2016, 08:17:29 pm
content: If you don't still know probe compensation has to be made, in X10 NEVER in X1.

author: SAUL BRITTO
author_rank: Frequent Contributor
timestamp: February 22, 2016, 08:30:30 pm
content: If there is no responsive control maybe a ribbon cabble is disconnected or a dry solder,It doesn't looks like so big, your problem.

author: tek465
author_rank: Newbie
timestamp: March 12, 2016, 03:50:19 pm
content: Thats what is currently wrong with my tek465. The vertical attenuator board has another smaller board attached called the virtual mode switch circuit board and that ribbon cable has some worn and broken connections in there (8 wires) and it was causing what looked like vibrations on the screen as well as some radical flickering on the upper part of the square wave upward several full units. Once left on for 20-30 minutes it would settle down. I removed the cable and re-seated it and now i have a non working trace, so I'm removing the board to fix the connections manually. So as others have said, re-seat the ribbon cables around the boards and see if that helps...-t4

author: tek465
author_rank: Newbie
timestamp: March 19, 2016, 08:06:04 pm
content: I just wanted to update this thread again and when i checked my 2246A it was also flickering and doing what the OP describes. SO i took my own advice and re-seated the ribbon cables but I am still having the flicker problem. It's less noticeable on a single channel and increases in intensity when all 4 are engaged at once. It appears like the trace at the far right hand side is not quite solid and looks broken up and sort of pulsing and is not a solid line. Have any of you seen anything like this before? thanks....settings.5v/DIV1ms/DIV-t4

author: tek465
author_rank: Newbie
timestamp: May 08, 2016, 05:41:20 pm
content: I have tried to search for answers on this one to see if anyone has solved the issue with these scopes and seems no one has. I found one thread where the person eventually gave up and sent it to a shop but never came back and said they fixed it and how it was done. Just for some more info as I am trying to solve the issue myself and hopefully will...the problem completely goes away when i turn the READOUT knob fully off which controls the intensity of the on-screen bottom and side menus. When its off the problem goes away, and only occurs once the READOUT circuit turns on. So that's where i have been looking for the issue. so any suggestions helps but i think Diagram 7 sounds very promising....You can get the service manual here:http://elektrotanya.com/tektronix_2246a_sm.pdf/download.html

author: tek465
author_rank: Newbie
timestamp: May 08, 2016, 06:18:51 pm
content: more more screen grabs for the casual viewer.... this is for a 2246 MOD A later serial....