Repairing the Spectra RF Board  

  The Spectra's RF boards are very similar for VHF, UHF, 800 and 900 MHz.

  They look about the same, but if the model number is missing, look at the soldered-on chip jumpers near the middle of the board, you can tell the band split.  (Look at the next photo down and I'll show you)

  VHF Boards:  (where x is the board revision letter)
     HRN6001x - 25kHz ch spacing, 5ppm stability
     HRN6004x - 25kHz ch spacing, 2.5ppm stability

  UHF Boards:
     HRN6003x - 25kHz ch spacing, 5ppm stability
     HRN6006x - 25kHz ch spacing, 2.5ppm stability

  800MHz Boards:
     HRN6009x - 25kHz ch spacing, 1.5ppm stability
     HRN6011x - 25kHz ch spacing, 1.5ppm stability, Wide IF
     HRN6010x - 25kHz ch spacing, 2.5ppm stability

  900MHZ Board:
     HRN6007x - 12.5kHz ch spacing

  This capacitor has leaked and dust from inside the radio has actually adhered to the leaked boric acid.  This is in immediate need of replacement before damage occurs.

  NOTE:  Just above the capacitor in the center of the picture, is a row of solder pads with a chip jumper soldered across two of the pads.  000 ohms represents a jumper or 000 ohms of resistance.  Notice that it happens to be soldered across the pair labeled "V" for VHF.

  The pads are labeled depending on the band split:

  L = Low Band VHF
  V = High Band VHF (great for 2m ham use)
  U = UHF Band
  8 = 800MHz Band
  9 = 900MHz Band

  Here I am removing the bad capacitors with hot air from my Hakko SMD rework station.

  Note:  While de-soldering the capacitors, if you smell a horrible stench, like bad fish, or something worse, then you have found spilled electrolyte! 

  Make sure you inspect the surrounding areas for acid damage.  It will get under solder pads, darken the solder mask, and corrode leads. 

  Capacitor removed, bad stench noticed, look at the upper pad, see the burned residue on the left side?

  More bad fish smell when this cap was removed.  Note the spilled acid between and above the pads.

  Here again, the 47uf cap leaked on the RF Board.  This is a bit rare.  Usually the 10uf smaller cap next to the 47uf will go.  And when it sits for a while, it will undermine the solder mask all around this area.

  Remove the excess solder with some good de-soldering braid and a low temperature, fine-tipped soldering iron.

  Here is what the pads look like de-soldered and ready for cleaning.

  Scrub the areas with a toothbrush and alcohol.  Use a lot, let is slop around, and work well out from the areas where the pads were to insure you clean up all the acid.

  (Note the alcohol all over the board and my bench.  Keep some paper towels handy.)

  A well cleaned board.

  Closely inspect the pads and areas around the pads for any damage to neighboring components, leads, traces, etc.

  If you have damaged traces or leads, this is the point where they must be repaired.

  (I will cover component, lead, and trace repairs in another section.)

  Note all of the electrolyte is cleaned up, board inspected, no damage present.

  As before with the control head, get the replacement capacitors, lightly tin their leads and tin the solder pads on the board.  If you get too much, use your de-soldering braid.

  Observe the correct orientation / polarity of the capacitors and carefully solder them in place.

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