Projets:Perso:2020:TEKTRONIX 2467B Add HeatsinkToU800

: TEKTRONIX 2465B - 2467B : add a heatsink to U800 horizontal output stage IC (TEK '155-0241-02')
Auteur	Eric
Date de proposition	Nov 2020
Tags du projet	TEKTRONIX 2467B,U800,'155-0241-02',heatsink
Utilisateur final	my 2467B
Type de projet Projet personnel de Eric

Projet : TEKTRONIX 2465B - 2467B : add a heatsink to U800 horizontal output stage IC (TEK '155-0241-02')

Mod for 2465/2466/2467 TEKTRONIX scope series Ajout d'un radiateur sur le composant U800 (étage de sortie horizontal) sur oscilloscope TEKTRONIX 2467B

Context

My TEK 2467B oscilloscope recently released some magic smoke : failure came from the mains filter C14 socket. Replacing the mains filter-socket 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-socket sucessfully 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 ! The nut on the left is the orignal one; the nut on the right is an additionnal one : it is good practice to keep the original right nut tighten onto the IC's steel tab

Additionnal information

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