Tektronix 2213 Repair

[TrendMend]

Hi Everyone!


(X-Post between EEVBlog and TekScopes@groups.io.)

I recently picked up a Tektronix 2213 from my local electronics recycler but unfortunately it is non-functional. Just in advance I want to let everyone know that this is my first time working with an analog oscilloscope, and one of few times working with any oscilloscope at all - My goal is to hopefully repair it and use it as my daily driver.

As of this minute, the 2213’s horizontal sweep does not seem to work correctly, taking up less than half of the screen and centered to the left side (I will post photos once my phone is charged). This is paired with a very odd signal coming through on both channels (Very remotely similar to this person’s scope

). This could be interference but it is still odd nonetheless. When the volts/div and the sec/div is increased (counter-clockwise), I am able to view the test frequency reasonably okay, but it actually shows up smushed on the right side. Also, when moving the position of either channel, it moves in a bit of a bell curve (to the left), and the horizontal position dial causes what’s shown on the CRT to shrink (or completely cut off occasionally).

I have already opened it up to find a replacement cap installed (albeit somewhat poorly with noticeable burn marks from a soldering iron) on C849, one leg of which is bent to connect to a resistor and the other connected to ground(in accordance to diagram 6).

Taking a look at the voltage test points, everything was in tolerance ALTHOUGH the resistance on +30 and +100 (if I recall, will need to double check) while being disconnected from mains (I don’t have an isolation transformer) was significantly lower than what the service manual described. I have already taken a look at the caps within the scope and under the shield, and none have leaked or blown, but I haven’t replaced them just yet (or the EMI filter) as I need to compile a list of them and I wanted to see if I could get the scope semi-functional beforehand.

Before someone goes off on me saying I didn’t set it up correctly, I did in accordance with the operators manual AS WELL as the service manual when going over testing procedures. I could still not have done anything correctly, but with the plethora of issues I am facing I really doubt that my misconfiguration is the cause of all issues. I also haven’t changed anything calibration related within the scope (just yet…) because I didn’t want to screw anything up more or make it harder for myself in the future.

If anyone has an idea of what is going on, tips / suggestions, really anything - That would be great!

Thank you very much!

EDIT: When I was just shutting it down right now, I noticed one of the neon lamps (DS868 I think?) light up and flicker out when I pressed the power button to turn it off. I found this little bit in the service manual but I don't know if that could pertain to the issue I am facing:

Neon lamps 0S867 and DS868 protect the crt from
excessive grid-to-cathode voltage if the potential on either
the control grid or the cathode is lost for any reason.

I guess potential is "being lost" on shutdown so nothing to worry about? Will have to take a closer look though.

[beanhauler]

Study the diagrams very carefully
First of all you need to make sure all of the voltages are correct at the op of the power inverter transformer.
If they are not then start doing some cold resistance checks on each of the power rails. looks like you have already done.
If they are wrong lift the wire links and see if it changes. I measured mine and they are all correct as per the manual except for the 5V rail which was supporting a lot of duff TTL. I am still slightly out but much better and homing in on where it is.
looking at the display it looks like you could have issues with the v driver and the h driver circuitry. Although you might get lucky with just smoothing caps to replace.
I'm going through a similar repair with the V attenuator where both nfets on the start of the vertical drive have failed.
My display like yours was very small and only had a tiny signal with the attenuator straight through and badly distorted.
I also only had one channel as most of the TTL's had blown up on the channel switching side.
The clue is that the voltages around q133 emitter and q233 are sitting up in the plus 6v area
You cant get j300's any more and the next best thing is 2n5245's which i am waiting on.

Check all the focus resistors cold and if they are old replace them with metal film. If the focus control is mid centre correct you should be ok.
One end of the 100v line feeds the intensity circuitry so check around here for short diodes etc which is around your 100v line.
C848/849 are spike removers and sitting at the end of the 27 ohm resistors...if they short...very unusual then you may get some issues.
Check Q850 Base and Q847 emitter voltages are correct.

As i pull this to pieces i will post any findings in terms of waveforms etc as i have the attenuator in pieces and under a refurb plus similar issues to your own.
Watch the tube multiplier feed and the focus resistor area. This is all sitting at about 2K and will hurt if touched and can be lethal.
Work cold where you can but if not one hand only with the probe.

[bdunham7]

The neon bulb thing is normal on shutoff.

First do a thorough physical inspection.  Check that all the cables going to the attenuator board are secure and undamaged and that all the screws are in place and tightened down.  Check that the horizontal and vertical deflection plates are properly connected--these are pins that stick out of the sides of the CRT about mid-point, there are oval slots in the shield and wires come up from the board and clip on to them.  Be very careful to only pull or push straight on or off if you work on these, as bending those pins will crack the glass internally and ruin the CRT.  Make sure there aren't any loose parts inside the CRT--just slowly tilt the scope around 360 degrees on each axis.  If you hear pieces rattling around inside the tube, you're done.

Next set the scope up to display a flatline for each channel.  Select coupling to GND, trigger to AUTO-PP, 5V/div and maybe 100uS/div sweep.  You should get two lines horizontally, one for each channel.  Move them with the vertical position knob and make sure they go all the way up and all the way down without distortion and report any anomalies.  The line should be roughly in the center when the knob is centered, and should move linearly with the knob.  If it goes one way and then stops or starts to reverse as you keep turning the knob in the same direction, that's a problem.  Same for the horizontal position, which as we already know, has problems.  See how it behaves.  Put the scope in XY mode and see where the point of light is and how far you can move it around with the V-pos and H-pos knobs--try them all.

Then take some pictures.

[TrendMend]

Hi everyone, thanks for the detailed responses!

I ended up getting it working after a chat over at TekScopes, turns out one of the deflection plate leads had come undone (right where I couldn't see it  ). For now, I still need to calibrate it, replace all caps, and then need to fix the focus issue (it looks a bit fuzzy). I'll make sure to keep this updated for when I finish it up in the near future. Thanks again!

[bdunham7]

Hi everyone, thanks for the detailed responses!

I ended up getting it working after a chat over at TekScopes, turns out one of the deflection plate leads had come undone (right where I couldn't see it  ). For now, I still need to calibrate it, replace all caps, and then need to fix the focus issue (it looks a bit fuzzy). I'll make sure to keep this updated for when I finish it up in the near future. Thanks again!

If the focus is unstable, or if you are in there replacing stuff anyway, replace the focus ladder resistors.  IIRC, there are 5 or 6 510K resistors and 1 180K, you'll see them in the diagram near the CRT with the focus pot in the middle of them.  The best part numbers to use there are Vishay HVR3700005103FR500 and HVR3700001803FR500--these are high voltage metal film resistors. 

[jdragoset]

Not sure if the focus pot for 2213 is the same as 2225 but I had one on a 2225 that had an open circuit resistance element and replaced with an older insulated pot on ebay.
Check the fixed focus resistors first and there may be a parallel fixed resistor across the focus pot element that has to have one side pulled to test the pot.
If it is the pot, take pix of the beast for recommendations because originals will be very rare or unobtanium.