[Boatanchors] Saga of a Telequipment S51B scope

[Philip Atchley]

Hi all,

A short time ago I posted to this reflector asking for information about 
a Telequipment S51B scope.  It turns out that it's bandwidth was only 
3MC, but it would still be useful for audio and LF work etc.

I got the unit working and replaced a bunch of out of tolerance carbon 
resistors, and it had a pretty nice trace.

This morning I put it back on the bench to correct a triggering 
problem.  First I thought I'd run it an hour or so to see if it was 
"heat related" or anything.  I had the trace set very dim so I could 
just see it without burning a line in the screen.  All seemed well.  
About an hour later I smelled smoke and heard a small "pop".  A glance 
at the scope across the room showed it had no trace so I quickly shut it 
off. 

Well, to make a long story short, there is ONLY ONE Paper capacitor in 
the entire unit.  A well hidden .05uF 2KV capacitor used as the high 
voltage filter.  All the rest of the capacitors are Poly, and I didn't 
realize that one was paper (and didn't have one to replace it with 
anyway).  It shorted out, took the High Voltage rectifier AND the high 
Voltage winding of the power transformer with it (those HV  windings 
usually aren't very beefy anyway)!

So, at this point I think the unit is probably history!!!   That's the 
first time in a very long time I smelled the aroma of burning power 
transformer and it isn't at all pleasant.  Well I guess I'm destined to 
be "scopeless". . .

I guess the moral of this story is, PAPER CAPACITORS OF ANY GENRE AREN'T 
TO BE TRUSTED AT ANY TIME!  This one was in a metal can with rubber end 
seals and was well buried UNDER the power transformer.

73 de Phil  KO6BB