Tektronics 2230 Trace issues - Page 1
Forum section: electronics / testgear

author: Mikeap53
author_rank: Contributor
timestamp: January 08, 2016, 02:06:44 pm
content: Hello everyone! I hope I can get my problem resolved here. I recently purchased a used Tek 2230 at a flea market for $50. What could I say I took a chance. Anyway it appears that it may have been dropped or something heavy fell on it. Channel 2 switch knob is broken but ordered. Channel one BNC was bent but is now straightened. There are no errors when fired up but no matter what I do I can't get a full trace on the screen. The two traces respond to frequency and voltage setting changes but can not be made any larger and when moved horizontally to the right it stops as shown. When moved to the left it goes a little beyond left as shown. I have tried every setting to no avail does anyone out there no what the problem might be? Maybe a problem with the horizontal supply voltage?I am not an electronic engineer I am someone who has an interest in electronics as a hobby and I figured a scope to be an essential learning tool. Thank you in advance for your help.

author: dan3460
author_rank: Frequent Contributor
timestamp: January 08, 2016, 03:12:56 pm
content: Can you move the line up and down? I have seen a few scopes where the "beam find" key has gotten stuck. What happens when you hit the bean find key?

author: Mikeap53
author_rank: Contributor
timestamp: January 08, 2016, 03:24:12 pm
content: Yes it will move and both traces can be moved independently, the beam can be found when the button is pushed and is not stuck.

author: dan3460
author_rank: Frequent Contributor
timestamp: January 08, 2016, 03:26:24 pm
content: So, just trying to make sure. When you press the beam find, the trace get smaller still?

author: Mikeap53
author_rank: Contributor
timestamp: January 08, 2016, 03:30:16 pm
content: yes just a single beam point to the right of center just below the horizontal line

author: Mikeap53
author_rank: Contributor
timestamp: January 08, 2016, 03:32:47 pm
content: Actually just one when in single channel, two beams when in two channel

author: dan3460
author_rank: Frequent Contributor
timestamp: January 08, 2016, 03:34:57 pm
content: Is probably my fault but I'm still not very clear with what happens. Can you take a picture with the two traces on the screen and then one pressing the beam find button?90% of trouble shooting scopes is done from the main panel, not even opening the scope. We need to understand exactly what is happening before we go to the guts.

author: Mikeap53
author_rank: Contributor
timestamp: January 08, 2016, 03:40:24 pm
content: sure give me a few minutes and thank you for the help

author: nctnico
author_rank: Super Contributor
timestamp: January 08, 2016, 03:40:30 pm
content: The text also looks too much to the middle. What happens when you switch the oscilloscope to digital mode (the store/non store button in the right top corner)?I think I see the problem: the 'horizontal mode' switch which select between A and B trigger (above the time/div selector) is switched to B. Move that to the left (A only).

author: Mikeap53
author_rank: Contributor
timestamp: January 08, 2016, 03:53:53 pm
content: Sorry took so long I have to take pics on my phone, resize and email to the pc and I had three, they exceeded the size limit on the page.

author: dan3460
author_rank: Frequent Contributor
timestamp: January 08, 2016, 03:59:00 pm
content: Ok, I get you. Did you try what NCTNICO asked? Now I will like to try another thing, with a signal on CH1 would the wave fill the whole screen? Sorry I mean top to bottom.

author: Mikeap53
author_rank: Contributor
timestamp: January 08, 2016, 04:05:27 pm
content: What happens when you switch the oscilloscope to digital mode (the store/non store button in the right top corner)?I think I see the problem: the 'horizontal mode' switch which select between A and B trigger (above the time/div selector) is switched to B. Move that to the left (A only).When I push the store non store in the beam disappears from the screen but can be found with beam finder.moved the switch to A only and now single beam (spot) but still can not be moved horizontally passed the grid just right of center.It is at the extreme at that point as adjusted with the horizontal position pot.

author: Mikeap53
author_rank: Contributor
timestamp: January 08, 2016, 04:14:20 pm
content: Yes it does, its like only the left side of the screen works. Hopefully these pics will show. the trace runs into a brick wall one grid to the right of center

author: dan3460
author_rank: Frequent Contributor
timestamp: January 08, 2016, 04:24:47 pm
content: That is not showing me what I want to see. Set up your scope as you have it in the beginning, where you see the two short lines. Then apply a signal to CH1. I'm looking to see if the signal is displayed at the correct amplitude.

author: Mikeap53
author_rank: Contributor
timestamp: January 08, 2016, 04:28:04 pm
content: I was taking this while you replied

author: dan3460
author_rank: Frequent Contributor
timestamp: January 08, 2016, 04:31:38 pm
content: I don't think the scope was set up in the same way that at the beginning. Set the scope to where you see the two lines as in your first post, then apply a signal to CH1.

author: Mikeap53
author_rank: Contributor
timestamp: January 08, 2016, 04:47:55 pm
content: Sorry I just noticed the post did not go through

author: dan3460
author_rank: Frequent Contributor
timestamp: January 08, 2016, 04:57:01 pm
content: Ok, that is not that bad. Just two more test to make sure. With the setup on the screen, move the times/div to the next step to the right, I just want to see a few more cycles in the screen. Then move the volt/div two steps to the left, making the instrument more sensitive to try to cover the whole screen from top to bottom.I just want to make sure that is not a tube voltage problem, depending on the result of the above test it will seem that is not enough deflection being applied to the tub

author: Mikeap53
author_rank: Contributor
timestamp: January 08, 2016, 05:09:28 pm
content: Sorry I was taking these while you were typing. Last pic is with x10 pulled out on sec/div switch

author: Mikeap53
author_rank: Contributor
timestamp: January 08, 2016, 05:11:55 pm
content: Do you know if there is an internal adjustment to move the beam farther to the right?

author: dan3460
author_rank: Frequent Contributor
timestamp: January 08, 2016, 05:26:00 pm
content: I think is a little more than just an adjustment, we need to trouble shoot the horizontal amplifier. What kind of experience do you have? Do you have some basic equipment: DVM, soldering iron, etc?

author: Mikeap53
author_rank: Contributor
timestamp: January 08, 2016, 05:29:36 pm
content: Yes I do. I'm 62 years old a retired master mechanic and licensed ham radio operator for almost 40 years. Sure I know enough to get me in trouble haha.

author: Mikeap53
author_rank: Contributor
timestamp: January 08, 2016, 05:36:06 pm
content: I have had it apart already to remove the bnc so I could repair since none in the junkbox and to straighten out the case a little. I did remove the plastic square plastic insulator above the HV part of the board and there was an area that looked like it may have gotten hotter that other areas.

author: dan3460
author_rank: Frequent Contributor
timestamp: January 08, 2016, 07:48:43 pm
content: First thing you need to do is to get the schematics for the scope, maybe you have already. Then following the adjustment procedures and measure the voltages out of the power supply. After that you are going to need to measure some voltages on the horizontal amp board. I would, find R780 and R770 and see if the voltages shown in the schematics are in the ball park on your scope.I imagine that you do not have a spare scope. We need to trace the sweep signal around the board, starting at the plate drivers (Q789 and Q779) and compare that with what is indicated in the schematics. BTW the manual that I was able to download is missing some of the wave forms.Maybe is someone with more experience that can help you.

author: Mikeap53
author_rank: Contributor
timestamp: January 08, 2016, 10:03:43 pm
content: I don't have another scope but I have raised the hood so to speak, raised the memory board and actually found a couple wires pulled from the connector from the cursor control to that board, I disconnected before raising it looks like someone did not.Well I was originally thinking Hor amp problem since there was nothing that would take it full screen width and from everything I read.I just watched a few youtubes and studied a few more articles I am sure I will find it eventually thank you so much for your time and I will keep you posted if I find it or need some help. Mike

author: tautech
author_rank: Super Contributor
timestamp: January 08, 2016, 10:13:32 pm
content: For everybody to stay on the same pagehere's some manuals:http://www.sphere.bc.ca/test/tek-parts/troubleshooting-scopes.pdfhttp://www.ko4bb.com/manuals/index.php?dir=Tektronix/Tektronix_-_2230