[EdHolland]

Returning to thoughts on FM alignment, here is something that is making me scratch my head:

Instructions for finalising the IF alignment ahead of the stereo decoder are confusing... The alignment instructions http://www.fisherconsoles.com/non%20cons...9%20sm.pdf are as follows...

• After aligning the IF passband, step one of aligning the discriminator calls for measurement at TP3 (total discriminator voltage) and adjusting top and bottom slugs for maximum voltage, with a 10.7 MHz unmodulated signal applied
  
• Second step in this calls for a DC measurement which is very poorly defined. Positive lead goes "To MPX output". Negative lead goes to "The junction of 47 k resistors connected between TSP3 and ground. Well, TSP3 doesn't exist. There is a TP3, used above, and a TSP103 in the Multiplex module (Right channel MPX detection circuit). It is hard to see how the latter would be the correct point.
  

Perhaps by "MPX output" they meant the discriminator output, TP4, which would have MPX (or mono) signal prior to DC decouping?  Perhaps the resistors are to be added at TP3, also in the discriminator circuit and the mention of the non-existent TSP3 is a mistake. I understand the intent of the adjustment - DC output of the discriminator should be zero for an unmodulated carrier at the centre of the IF - and that is the only effect the requested adjustment could have. It is instructions for the way that this is measured which are confusing.

Presumably the 47k resistors are to be tacked in by the tech doing the alignment - there is nothing on the schematic of that nature.

If anyone followed along my ramblings - thanks