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Tektronix 2465A Oscilloscope Repair – Part 2

 

Tektronix 2465A Oscilloscope Repair – Part 2

Lithium Battery Replacement

After checking the High Voltage Power Supply and repairing the “shrunken screen” symptom in my previous post, I continued on preparations to calibrate the scope. This will hopefully result in a properly working scope, free of diagnostic errors on bootup.

The next step is to replace the bad lithium battery. This battery is used to store calibration constants as you run through the calibration steps. If we don’t replace the battery before the calibration, any changes made will not persist, and we’ll just have to do the whole calibration again.

Here is the culprit that needs replacing on the A5 board.

 
Old Battery

The old battery was only reading about a half volt, when it needs to be about 3.6 volts.

 
Old Battery Voltage

I started to desolder the old battery using my soldering iron and spring-loaded solder-sucker. It felt like the traces were kind of fragile, and I was having a hard time getting the solder clear of the battery lead and hole. I got a new Hot Air Rework station for Christmas this year, so I thought I would try that instead.

 
Hot Air Rework Station

I just attached the small air tip, set the temperature to 300 degrees Celsius, and set the airflow at about halfway on the scale. Then I waved the hot air over the four battery leads, lingering a couple seconds over each one before rotating to the next. 20 seconds later the old battery just fell out of the holes.

I finished cleaning out the holes with my normal soldering iron and solder sucker. This worked fine without the leads in the way.

 
Battery Removed

Next, I placed the new battery in place and soldered it in, using my normal soldering iron.

Battery Replaced

 

New Battery in place

 

The voltage on the new battery is 3.66 volts. Just right.

 
New Battery Voltage

So that sets us up to begin the calibration. Stay tuned…

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