Electronics > Repair
TEKTRONIX 2213A CRO Oscilloscope - XY Mode Issue - Only half a circle
BTO:
TEKTRONIX 2213A CRO Oscilloscope - XY Mode Issue - Only half a circle
Hi Guys,
SUMMARY :
I Recently bought a C.R.O. and am in the process of testing if it all works.
I'm 50 years of age, Been into electronics as long as Dave and am not new to scopes CRO or DSO.
I suspect i actually do have an issue on this one and just wanted to bounce ideas of everyone before cracking it open for a repair.
Already searched the internet for several days on issues relating to X-Y Mode not working properly and only getting half a circle.
Most of what comes up is...
- How to get into XY Mode
- Yes i have R.T.F.M.
- What to do if having trouble getting into XY Mode
i already know all this.
I have tested my Rigol against another CRO, a Kikusui, XY Mode works perfectly as expected.
and while doing the same thing on this CRO the result is not the same
HARDWARE :
TEKTRONIX 2213A
60MHz
Dual Channel
KNOWN WORKING SCOPE (For Signal Generation)
DSO
Rigol MSO5074 (Upgraded to MSO5354)
350MHz
4 Channel
16Ch L.A.
2 Channel Signal Generator up to 25MHz
The MSO5000 will be our Known working Device
and the Tektronix will be our D.U.T.
THE PROBLEM :
X-Y MODE DOES NOT WORK AS EXPECTED (Details below)
GOAL :
to get into XY Mode and have an Oscillating Circle by Putting 1 channel on 1000 Hertz and the other channel on 10001Hertz.
TROUBLESHOOTING thus far
- Tektronix Power ON Test - Powers Up
- Tektronix Basic Trace Test - it powers up with a trace (WE HAVE A TRACE)
- Channel 1 Signal Test - Passed , Sine Wave, 5V, 1Khz loaded successfully.
Note : also tested on Square wave and triangle waver and on various frequencies from 10Hz to 1KHz, 10KHz, 1MHz, 10MHz
Channel 1 works perfectly as expected
- Repeated same test on Channel 2 - Channel 2 works the same and as expected
- The switch from Channel 1, to Both to Channel 2 works perfectly
- Focus, Intensity, Trigger all seem to work fine
- Trace rotation has been checked and adjusted on DC to be straight
- Photo 8 shows the switch flipped to BOTH position and both traces work
- Photo 9 shows me selecting XY Mode correctly
- Photo 11 shows, I'm in XY Mode However....
the trace was initially to the far left and i had to adjust the Horizontal position to get it to the middle
Second issue, the trace is not Diagonal, it's Vertical. AM I WRONG HERE ? it should be Vertical in XY Mode, right ?
Because XY Mode Plots Channel 1 against Channel 2
- Photo 16 Shows the problem.
XY Mode works.... sort of .
when Ch 1 on the sig gen is 1Khz and Ch 2 is 1001Hz
Half the circle behaves absolutely as it should and expected
the other side just remains as a vertical line
The vertical line is representing Ch 2 on the scope, because if i exit XY Mode and change the Amplitude Base it is Ch 2 that changes in
amplitude
SO GUYS
ANY IDEAS HERE
1. Why am i not getting a Horizontal line upon entering XY Mode
2. Why do i not have a complete circle in XY Mode
3. Why is the trace starting all the way to the left and not as a diagonal expression in the middle of the screen ?
ANY IDEAS
I'm thinking, Faulty internals that control Channel 2
ANY THOUGHTS
BlownUpCapacitor:
I would guess really really really bad phase offset in the x-y mode?
I'm not sure....
I'll look through the service manual and report back later.
I know you have lots of experience with scopes, but it can sometimes help if you follow settings exactly as listed in manual.
CRT:
Best focus
Desired intensity
Vertical:
Both channels set to same sensitivity and correct sensitivity for x-y operation
BW limit off
Ch2 Invert off
Both Channels GND couple
Vert mode ALT
Horizontal:
X-Y mode
Horz Mode: No-dly
Trigger:
P.P. Auto Trig
Positive slope
Ch1 Trig source
Trigger Source: INT
EXT couple: AC
Varhold off: Norm
Now with these settings, use the horizontal and ch2 position controls to center the dot to the middle.
Connect signals, and set both channelsto DC couple.
What do you observe?
BlownUpCapacitor:
After looking at schematics, check the following transistors:
Q732
Q737
Q742
Q743
They amplify the X-axis signal from CH1.
Don't pull them out. Use another scope to trace the signal from CH1 in X-Y mode. Follow the schematic on page 159 here https://w140.com/tekwiki/images/e/e5/070-4733-00.pdf
Follow the signal until it looks "wrong", maybe the wave is cut in half, or it's out of phase.
bdunham7:
Try this:
Select the XY mode, remove any inputs and set both channels to 1V/div and GND. There should be a dot somewhere, hopefully on the screent. If not, use the beam finder and intensity controls to brighten and locate it. Then adjust the CH1 and CH2 position knobs until you get the dot right in the center of the screen. Then use the CH1 and CH2 position knobs, one at a time, to move the dot to the edges of the screen. Can you put the dot all the way to the top/bottom and right/left?
After that, you can connect the inputs and change the input coupling from GND to DC on one channel at a time and adjusting the input gain to see if you can get a vertical or horizontal line as wide as the entire screen-or not.
BTO:
"I know you have lots of experience with scopes, but it can sometimes help if you follow settings exactly as listed in manual."
Thank you for the initial respect, it's appreciated.
but i have indeed RTFM (and stated that in the troubleshooting), it is however possible that i have made a mistake somewhere.
so....
CRT:
Best focus - CONFIRMED
Desired intensity - CONFIRMED
Vertical:
Both channels set to same sensitivity and correct sensitivity for x-y operation - CONFIRMED
BW limit off - CONFIRMED OFF
Ch2 Invert off - CONFIRMED OFF
Both Channels GND couple - CONFIRMED and when ground coupled there is obviously no trace
Vert mode ALT - CONFIRMED ALT
Horizontal:
X-Y mode - CONFIRMED (as per the picture)
Horz Mode: No-dly - CONFIRMED delay off
Trigger:
P.P. Auto Trig - CONFIRMED
Positive slope - CONFIRMED
Ch1 Trig source - CONFIRMED
Trigger Source: INT - CONFIRMED
EXT couple: AC - CONFIRMED
Varhold off: Norm - CONFIRMED
Now with these settings, use the horizontal and ch2 position controls to center the dot to the middle......... DONE
Connect signals, and set both channelsto DC couple.
What do you observe?
EXACTLY THE SAME THING... NO CHANGE
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