Odyssey, board A

Finally on to the parts swap and electronics repairs with my precioussssssssss! On board A, the parts that got swapped were R36-R46, C3, C9, C10, C12-C15 and C18. I didn’t have any suitable replacement for C16 at hand so I just left it as-is. In case you never memorized the locations of these parts, why not take a look at p27 of this service manual.. ;)

Broken items on board A were the up2oct calibration trimmer T4 (measured 4Mohms instead of 250R), FET Q8 of the CV output FET-input opamp buffer (not driving CV out higher than 4,5V) and pink noise generator opamp A4 (no output). There was also a bad solder connection on R32 (2nd voice output buffer opamp feedback resistor), this caused the 2nd voice CV output to drift at random.

As a  replacement for T4, I decided to use a multi-turn trimmer. Despite the part didn’t really fit anywhere near the through-hole spacing on the board, I managed to get the trimmer in place without extra cables or such.

Multi-turn trimmers on board A.

As the multi-turn trimmer was so much more easier and precise for calibration, that I decided to replace also T2 (2nd voice calibration). For quite some time I was planning to use the same part to replace all the trimmers, but the rest loosened out relatively ok after a bit of repeated tweaking. Which brings me to..

HAWT REPAIR TIP: Having problems adjusting some old trimmer? Repeatedly tweak it back and forth all the way from one end to another for a while. Most of the time this loosens up some of the dirt accumulated on the contacts over the years, making precise adjustments slightly easier. If you want to get all fancy, use some contact cleaning spray as well!

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