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Scope, cooling ICs - refresh or not?


Staffan
 

Hello,

I have an TDS744A oscilloscope, which is working really well. Just adjusted screen brightness and it is almost as new!
I believe I've seen some discussions that the heat transfer paste (silicon grease?) between components and the coolers may dry out over time. This unit has quite a few coolers and they got reasonably warm just during the time it took to adjust the display. They seem actually to be glued on top of the ICs - unclear how.
Question is: can - or should - the cooler interface be refreshed by adding some paste or similar? What would be the proper way in that case?
I imagine a unit of this age with a 2 GSPS acquisition can get fairly hot. Does anyone have suggestion for which ICs should be paid attention to (there seems to be six bigger and two smaller coolers on the acquisition board)?
I have seen general comments, but can't say I've seen specific suggestion for what devices on the 744 that should be taken care of. Are there more coolers than the ones visible when just pulling the cover?

Regards,
Staffan


DaveH52
 

If you're talking about the hybrids with the 4 screws holding them, leave them alone. Other heatsinks may be thermal-epoxied to the chip and would be a lot of trouble to clean up and re-epoxy. Not to mention you've got to find and buy special thermal epoxy to use.


Tom Phillips
 

Hello Staffan,

You said "This unit has quite a few coolers and they got reasonably warm just during the time it took to adjust the display."

Those "coolers" are the heat sinks and the fact that they quickly get warm indicates that they are in good thermal contact with the component they are cooling and are therefore doing their job.

Personally, I do not recommend removing heat sinks just to replace the thermal compound between the heat sink and the device they are cooling.

Cheers,
Tom


Staffan
 

Hello,

Good comments, thank you. I was sort of hoping for this information - just didn't want to end up with an "Ooops, should have known that..." when the devices overheat. Feels a bit more comfortable now.

Coolers - heat sink. Yes, the word just slipped my mind when writing...

Regards,
Staffan