Re: 2465B SN 55xxx with TEST 05 FAIL 40

Tom Gardner

My technique, which I used to replace the capacitors and one SMD resistor in the middle of the others, was:

* play a soldering station's hot air gun over the relevant component until the
solder melts and it blows away (do a few experiments to see which
temperature/velocity works best, and use a narrow nozzle)
* protect the surrounding components by loosely covering them with
kapton/polyimide adhesive tape, to deflect the hot air away
* clean the pads etc by any means you choose; I used IPA
* dab solder paste on the pads
* place replacement components, using solder paste as an "adhesive"
* use hot air gun to reflow that component
* remove polyimide tape

On 10/10/18 17:02, tekscopegroup@... wrote:
Right you are, only 4 SMD problem caps total. I need to have the board in front of me for facts to start falling in place. Definitively will carefully chop apart the caps before attempting removal. I did not intend to disturb any tantalums, unless really necessary. I've also read that the 20K trimmer pot near the DAC sometimes gets also damaged and needs to be replaced before the ref voltages are correct again. Maybe just order it too along the caps, just in case.

Your cleaning procedure makes a lot of sense, something I've not seen explained in detail anywhere else. Usually one would cringe at the idea of splashing water on a board like this, but now I am reassured it will be the best thing to do, even if corrosion damage appears to be light (due to fumes spreading on all nearby surfaces) its worth doing it right.

Do you by any chance know what Option 46 would be for this scope? Its the only field on the rear panel that has a punched hole in it.


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