Tektronix 2400 Series Scope Hoz. Output IC Failure - HowTo Confirm

[tec5c]

I decided to make a short video after my Tektronix 2465BDV had developed a fault, in which after booting up the unit the display would be normal for around 30sec - 2 min and then it would disappear. Sometimes you could see the display quickly drift off to the side (left in my case). I knew the IC, location: U800, was no longer available and fairly expensive to buy second hand. I did not want to spend over $100 on an IC and then find out it did not fix the problem.

The video shows the unit after completing boot up stage and the display is as expected. The fault soon after occurs and the display disappears, just before this happens the frequency readout tends to jitter quite extensively (it's not so visible on camera). I spray some instant freeze on the suspected IC and the you can see the display slowly drift back onto the display, confirming the IC to be the cause. After shooting this video I have now confidently ordered the IC from the US and am looking forward to getting the scope back up and running.

I hope someone may find this video helpful. It is my first youtube clip and I didn't commentate throughout so it could be better perhaps.




Jason.

[BravoV]

Hey Jason, thanks for the video, this is definitely a good reference for old analog tek scope owners that have the Unobtainium800 IC.

Really sorry to hear this nice scope is having problem, hope the replacement will fix that completely.

As a 2465B owner, currently I used two copper sinks on top of it with sticky 3M thermal pad.



Actually I was planning to make a better thermal contact thru the bottom of the ic body since that metallic tab is exposed like this pic below, but still have no time to do it cause this will need a major workout at the big main A1 board. 



Fyi just in case you're not aware of it, be careful, the ic's metal tab is -5 volt instead of ground. 

If you have extra plan to cool this precious IC when you're going to replace the old one, share it here please.


PS : Made a teardown thread of my 2465B while ago here -> https://www.eevblog.com/forum/product-reviews-photos-and-discussion/tektronix-2465b-oscilloscope-teardown/