Tektronix 2213A repairing vertical preamplifier.

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I am currently trying to repair the board for the vertical amplifier for my oscilloscope. Most of the repairs are done, but I am currently stuck on what to do for the channel 2 knob.

I am currently ordering a replacement knob for that channel since I still have a good working skirt for it with the values printed on it. However, in the picture the white piece on the left of the picture is completely broken. I am not sure where to go to from here. I could try to glue it, but I don't believe that will solve my problem. I would like to purchase a replacement part. I just do not know for sure if anyone sells it, what this piece is called, nor the model number if it has one. Anyone have any ideas?

[tautech]

Welcome to the forum.

Is there anything on this page that matches?
http://www.sphere.bc.ca/test/tek-parts/tek-knobs.html

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Thank you for the reply. Nothing I could really see matched the part I need.

[tjg79]

Try eBay for a non-working scope for parts. Go for the Best Offer auctions and low ball an offer. You might get lucky and a good reserve of spares. You can sometimes buy a whole scope for the price some sellers want to you just a knob.

[NilByMouth]

That looks like part number 377-0512-00 (looking at the exploded diagram in the service manual). Qservice don't even list it. Best bet is to keep an eye out for a spares/repair donor scope.

https://www.hellspark.com/dm/ebench/tools/Analog_Oscilliscope/tektronix_2213_service.pdf

[NilByMouth]

Alternatively join the Tekscope Yahoo group. They are extremely helpful and I have managed to get parts from other members.

[alsetalokin4017]

That looks like part number 377-0512-00 (looking at the exploded diagram in the service manual). Qservice don't even list it. Best bet is to keep an eye out for a spares/repair donor scope.

https://www.hellspark.com/dm/ebench/tools/Analog_Oscilliscope/tektronix_2213_service.pdf

Ah.... no, I don't think so. 377-0512-00 is an insert for the small knobs for vertical and horizontal position, trigger level and holdoff and focus pots (items 62, 63 and 67 on the exploded diagram), and there are 6 of them.
 
Besides, the 2213A has vertical attenuator switches and board like in the 2215A, not like in the 2213 no-letter.  The black pieces in the OP's photo are the camshafts 105-0395-00 that actuate little contact switches on the VA switchboard. These replaced the rotary switches that were used in the 2213 no-letter version.

The broken part _may_ be 376-0209-00, coupling shaft... maybe. It's not even shown on the 2215a explosion that I have.

[NilByMouth]

https://www.hellspark.com/dm/ebench/tools/Analog_Oscilliscope/tektronix_2213_service.pdf

Ah.... no, I don't think so. 377-0512-00 is an insert for the small knobs for vertical and horizontal position, trigger level and holdoff and focus pots (items 62, 63 and 67 on the exploded diagram), and there are 6 of them.
 
Besides, the 2213A has vertical attenuator switches and board like in the 2215A, not like in the 2213 no-letter.  The black pieces in the OP's photo are the camshafts 105-0395-00 that actuate little contact switches on the VA switchboard. These replaced the rotary switches that were used in the 2213 no-letter version.

The broken part _may_ be 376-0209-00, coupling shaft... maybe. It's not even shown on the 2215a explosion that I have.
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Yes, I am mistaken. The 2213A is a completely different animal to the 2213 - the 2213A and 2215A were different releases. You can get a really good scanned copy of the 2213A manual from Artek Manuals for a small price  (no affiliation etc.). They are text searchable too.

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I went ahead and joined the Tekscope Yahoo group. Hopefully I can find some information there as well. Honestly this is a very very specific part that I doubt it is sold separate to the vertical preamp board. Assuming no part like this exists for easy replacement where do you suggest we go to from here. I could try to glue those pieces back together. However it is keyed for the nob and the black shaft and must be able to handle torque stress placed on it. I doubt gluing it will hold. Maybe it might be possible to machine another piece out of similar plastic since I still have a perfectly good one to work off of? Or I could possibly go with my archaic plan of soldering wires to it and wiring up a push button board to simulate the settings the knob would enter.

[alsetalokin4017]

I went ahead and joined the Tekscope Yahoo group. Hopefully I can find some information there as well. Honestly this is a very very specific part that I doubt it is sold separate to the vertical preamp board. Assuming no part like this exists for easy replacement where do you suggest we go to from here. I could try to glue those pieces back together. However it is keyed for the nob and the black shaft and must be able to handle torque stress placed on it. I doubt gluing it will hold. Maybe it might be possible to machine another piece out of similar plastic since I still have a perfectly good one to work off of? Or I could possibly go with my archaic plan of soldering wires to it and wiring up a push button board to simulate the settings the knob would enter.

If you can't find one through the Tek forums...

The "best" solution would probably be to find a broken, "for parts only", 2213a or 2215a that still had this part intact. This would also give you lots of other parts for eventual repairs.

If you have all the broken pieces, you might try gluing it back together very carefully with a good quality cyanoacrylate adhesive ("CA", check your local hobby shop for the best grades, and test it on the plastic to make sure it's compatible first). If you do your surface preparation properly and use the right adhesive the part will probably be as strong as the original. At least it could be worth the effort to try. Then just remember "gently gently" when you are switching the attenuator to avoid breaking it again.

If you have the skills and tooling you probably could machine one out of Delrin (acetal) plastic or some such, but it looks to be fairly complicated with the flanges and notches. This is something that would be a "labor of love" and if you have to hire someone to do it, probably not worth the effort.

I would strongly advise _against_ trying to bodge something up like external switches for the vertical attenuator board. This is a very critical part of the scope's performance and added wires and such will add inductance, stray capacitance and would probably not work very well even if you could do it. 

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Thanks for all the replies. I went ahead and bought a whole new vertical preamp unit which has the parts I need on it. War a bit more expensive than I had wanted, but if at any point a part breaks I got some spare. Thanks for all the replies everyone.