Kapanadze Cousin - DALLY FREE ENERGY

[NickZ]

    TK: 
    Yes, there are somethings that I would not do again. But I got several of the tiny mosfet driver chips, so I'll try them out. You really need pointy soldering iron tips and fine solder to do decent job on that small a chip.
   I'm waiting on some more resistors and 12v zeners for the snubbers. But I'll build up what I can until then.
   I'll see what kind of output signal I get from the tiny mosfet drivers tomorrow. 

   I don't want to risk causing any more damage to my scope until I finish the push pull driver, to see how it looks and works on the scope, before I open her up for repairs. I'll check the focus resistors. More likely than the pot, as you can tell when the pot is going out, sometimes, before it fails altogether. This happened quickly, possibly from overheating. Maybe from my fault as I left the scope covered all night long and forgot that it was still on
But I'll fix it, soon enough.
    Thanks for the suggestions.

[starcruiser]

@NickZ, could also be the HV from the flyback as this is a tapped output which usually provides a couple thousand volts to drive the focus grid.

[NickZ]

   I just posted a new video on youtube. Please look for it under my name Nick Zec.
   I can't post a link to it.
   Showing the TL494 and mosfet drivers on the scope.
   Let me know what you think.
   Dated March 22

[TinselKoala]

   I just posted a new video on youtube. Please look for it under my name Nick Zec.
   I can't post a link to it.
   Showing the TL494 and mosfet drivers on the scope.
   Let me know what you think.
   Dated March 22

Why can't you post a link? I hope you don't mind if I do:
https://www.youtube.com/watch?v=TlzBKNOth94

Two comments:
First, when you adjust the Frequency pot to give more cycles on the screen you are _raising_ the frequency, not lowering it. More cycles on screen = higher frequency (for a given scope timebase setting.)
Second, when you finally connect the mosfets, you probably should use a duty cycle setting that results in a tiny "gap" between one mosfet turning Off and the other mosfet turning On. This will assure that both mosfets can't be On at the same time. If both mosfets are On at the same time, this can result in "shoot-through" which can cause component failure.

Also, you can get or make "breakout boards" or adapters that will make it much easier to use the surface-mount parts in your build.
https://learn.adafruit.com/smt-prototyping-using-breakout-pcbs/overview

And again also.... I don't remember if you have the Service Manual for your scope. If not, here's a link to the SM at my favorite Tek "fansite" :
http://w140.com/tek_2205.pdf
The resistor ladder for the Focus control is in the schematic section on page 192 of the pdf. It's kind of blurry, you may be able to find a better scan of the SM on the internet.
They are a bunch of 510k resistors in series, connected to the focus pot.

[NickZ]

   TK:
   Thanks again for your comments and suggestions. They will not be overlooked.
   I do have an original Tectronix 2205 manual,  as well as a downloaded one off of the web. I also now have the service manual that you just linked to.

   I thought that the purpose of the driver chip was to assure that both mosfets don't fire at the same time. In any case, that does not seem to be a problem.
  My intension was to have all the push pull driver components on a single PCB, as well as the kacher circuit.
But I was sent the wrong size driver chip. Anyways, it's all good, and seems to be working.

  My PC is down, and I bought a new motherboard and memory for it.  So I should have it up and running in a few days, when that order gets to me. In the meantime I'm having a hard time placing links from YT. So,  thanks for placing it for me. 
  Doing things on a phone or tablet can be a pain in the butt.