Quad FM4 fixup

[martinr33]

I picked up a late model Quad FM4 tuner, non-functional. No display.

1) The schematic has the microcontroller pins mislabeled. The schematic pins are labeled backwards. This can be confusing...

2) Reconfigure for 110V operation. Odd that this was not already done. Display came back, but showing 150MHz.
   - the FM4 is clever - the display is a frequence counter right from the IF section, so what you see is the input frequency
   - uses a long-obsolete high speed ECL divide by 100 chip.

3) Acid damage from a previous leak. The unit had a new NiMH Varta pin compatible battery installed.
    - replace all damaged components.  Two diodes, one zener, a resistor and a 180 pF capacitor, plus the microcontroller socket
    - clean up PCB, remove all corrosion.

3) Although not obvious, the damage had opened up the ground trace that feeds the tuner front end. So nothing worked until I bridged that.
      - Display now reads correctly but tuning range was off.

4) Display was noisy, flickering up and down a few steps
     - went away after running overnight, presumably after charging the battery.

Unit now seems very stable, locks in to stations and displays signal strength.
Next up is audio testing.