Revision as of 16:30, 17 November 2020

Context

My [1] recently released some magic smoke : failure came form the mains filter C14 socket. Replacing the mains socket-filter needs some time (2-3 hours) because gaining access to the defective part requires the whole power supply assembly to be removed :(

Add a heatsink to 2467B U800 horizontal output stage IC

As the scope was open (and it's mains filter sucesfully replaced), I choose to make use of the opportunity to add a small heatsink to the rather fragile Tektronix "155-0241-02" U800 horizontal output stage with is difficult to find as spare part. A design that duplicates the parts functionality can be found here

The famous U800 '155-0241-02' originally branded 'TEK' in his heasinked DIP-24 package (one side steel tab); some units might also be branded 'MAXIM'

I could find a small heatsink in my junk drawer.

Lenght : 110 mm

Width : 16 mm

Height : 12 mm

Luckilly, its bottom is already coated with a kind of yellow thermally conductive foam/compound.

A small heatsink found in my junk drawer (pen is for size comparison)

How to proceed ?

Shorten the heasink to a lenght between 45 and 60 mm : there's actually enough room on the tab side of the IC so that the heasink can be slighly longer than U800.

Remove the fins where the hole(s) have to be placed.

Bore diameter : 3 mm

Distance between the two mounting holes : 36,9 mm

Two fins removed, two 3 mm holes added

Installation on top of U800 is rather straightforward by using an additional nut and washer, as shown on the picture below.

Done !

Additionnal information

The same kind of improvement can be seen at 1:24 on this video made by Philippe Demerliac on a 2465B.