Re: Tektronix 2235 small/not work trace line move


tom jobe <tomjobe@...>
 

Hello,
Your burn spot is very common on 22xx oscilloscope family when the scope has been turned on 24/7 and the scope was in a level position such as being in a rack mounting or on a shelf.
On the later 22xx production, Tektronix raised some of those resistors and a photo of the later production resistor mounting method is attached.
You can raise your capacitors up in a simple way, photos of that method are also attached. I will add those photos to your photo album too, in case you can't see the attached photos.
If you do raise your resistors up, consider raising up more of the resistors than Tektronix did, using your burnt area to decide which ones to raise up.
Looking at the resistor values, I would doubt the resistors are causing you much of a problem, although your R268 is off by quite a bit.
Perhaps you could leave the resistors as they are for now, and check that all of the low voltages are correct in your scope, both in value and in ripple content?
tom jobe....

On 6/3/2018 9:34 AM, Andrey Ulyanchenko via Groups.Io wrote:
Hello sir! I need advice on replacing the resistors of the output amplifer. Sweep lines are very limited. Before replacing the resistors I ask here, it is possible to prompt what else to check. The nominal values of my measurements are signed on the diagram. A significant deviation in nominal values was found in R262, R257, R259, R268. The transistors are in good working order, the more the scanning lines are visible for both channels, they are simply poorly regulated vertically.
Thanks for the help.
p/s/ See my photo Tek2235 Heat resistor
https://groups.io/g/TekScopes/album?id=54693

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