[time-nuts] more 5370B

[Magnus Danielson]

Connie Marshall skrev:
> The heat sink on the back of my 5370B runs very hot. Can't touch it for more
> than a fraction of a second. Maybe some where around 140F. I assume this is
> not normal??

Sounds a little too hot (C would give me better indication). Check the 
regulated and unregulated voltages. There are 4 transistors there. Do 
you have the manual? There's a PDF for it and you want to check out the 
A6 board (which often is described together with A1).

+10V is regulated into +5 V and fuse is for 7 A. So about 35W is burned 
in Q2 before fuse blows.

+20V is regulated into +15 V and fuse is for 1,5 A. So about 7,5 W is 
burned in Q1 before fuse blows.

-20V is regulated into -15 V and fuse is for 1,5 A. So about 7,5 W is 
burned in Q3 before fuse blows.

-10V is regulated into -5.2 V and fuse is for 7 A. So about 33,6 W is 
burned in Q4 before fuse blows.

So about 80-85 W may need to be fumed out without having the fuses blow.
More if the power-plug is put in 100 VAC rather than 120 VAC.

A well designed switch becomes muke warm, and it makes minor wonders for 
reliability. :)

Cheers,
Magnus