[Heathkit] IO-104 O'scope Horizontal Board

[Donald Spoon]

My venerable old IO-104 oscilloscope quit working properly the other 
day.  It had recently been brought out of storage and was working OK for 
the last month. 

The symptoms are that the trace starts on the R half of the screen and 
cannot be moved back to the L. side.  Adjusting the Astig and Focus 
controls cause it to move to the R.  I have done some voltage 
measurements and it seems like they are off on both Q323 (JFET - EL131) 
and Q325 (PNP - TZ582).  The base voltage of Q325 (drain of Q323) is 0.2 
V where it should be 0.9V.  Its counterpart on the other side  (Q326)  
measures OK at 0.9V.  The other thing that seems to be off is there is a 
small difference between the + and - 9 volt supplies.  The + side is 9.1 
V and the - side is 8.8 V.  This could upset the drain voltage (0.9V) on 
the JFET, which sits between the +9 V and the -9V supplies. 

I cannot find these semiconductors but maybe I am not looking in the 
right places.  It looks like a MPF 102  might work in place of the 
EL131.  I cannot find a sub for the TZ582.  Does anybody have any 
suggestions / comments /  corrections??

-Don Spoon-
K0APK