[Techtoolslist] Recommend add a fuse upgrade for Fluke 9100 series

[Ian Eure]

John Robertson writes:

> I am now on the hunt for the small switching transformer on one of my 
> 9100s as the original was cooked. Unfortunately it was not fused by 
> Fluke and I am not sure where I am going to find this sucker. It is T1 
> and is called Transformer, Converter 775932 (manufacturers #89536) in 
> parts listing.
>
89536 is the manufacturer code for Fluke.  Many parts in the 9100A
service manual are listed this way, even if Fluke wasn’t the actual
manufacturer.


> Shy (@ Navatek) hasn't seen one before but is still checking...
>
> This is a multi-winding sucker and provides the isolated voltages for 
> the serial ports as well as the 70V for the display. Years ago I had a 
> secondary cap (C101) short on this transformer and it let the magic 
> smoke out. I had set it aside and forgotten, but now I am restoring a 
> few 9100s and dug this out and found the smoked Xformer.
>
> In the meantime I have modified all my 9100s lifting the furthest leg of 
> inductor L2 (10uH) away from the power connector J15 and then add a GMA 
> fuse holder in series from raised leg and the PCB. I find a 300ma fuse 
> works just fine. Which is interesting as Fluke put a 1A fuse in the 70V 
> output to the display...obviously overkill!
>
The fuse on the 70V line is supposed to be .125A, not 1A.   Maybe the
original popped and someone put the 1A part in, and that’s why your
transformer is wrecked.

  -- Ian