[studeb]

i am posting this here, as other boards don't seem to be too helpful 

I have a FM-1 with the multiplex on board. The quad cap failed, so it has been replaced along with the plate resistors on the IF board and R 89 90 on PC-12 and C29. I have not yet replaced the PEC modules C31.
In spite of that i followed the alignment instructions. It all went well until the multiplex part. T71 can be adjusted to close the tuning eye, it will stay closed for half a turn, then opens again, so i centered it. But if the eye closes fully when you do T71, how do you close it for T72?
Turning the top or bottom slugs of T73 would not make the eye move. I could hear the signal go from mono to stereo for half a turn, so i put it in the middle position each top and bottom and left it there.

I replaced R81-84 last night with a matched set at 47.1kohm, I also heated up the L1 pads to improve a cold solder joint and got much better reception, but only repeated the MPX alignment part. and got similar results with T71-73. Only now i have a high pitched whining on stereo broadcasts.  Should i start at the beginning again?

Would removing the antenae help?

Also for the discriminator alignment i used a DVM, but could only get -6.9ish volts. Is that okay? Because its a DVM, not a VTVM?

thanks for any help

[baldrick]

If you are getting a whine on the multiplex board then you are amplifying the multiplex carrier frequency.
Re-read the MPLX alignment instructions.  You have to move a resistor from place to place to align T71 and T72 properly.

As for the discriminator, if you are getting low voltage then do a full alignment again, and when you get to the discriminator part find a stronger station.  It doesn't necessarily have to hit -9 volts, but you do have to find a peak voltage, then a zero voltage.  A decent DVM will work fine.  Most have a high enough input impedance that they will not load down the circuits you are trying to measure.
PM me if you get into trouble.  I've done plenty of FM-1s and FM-3s.