[TenTec] ORION vfo encoder symptoms

[A R]

   My recently acquired ORION 565 is one great radio, but has one annoying trait. Upon power-up, the panel-mounted VFO A encoder ignores rotational travel over about a 180 degree arc. The dead area of arc is consistently over the same rotational position, and independent of "STEP" settings. 

As the radio warms up, the "dead" arc diminishes, and after about two hours of power-up, output of the encoder is good over the full 360 degrees of rotation. The 302 remote encoder provides output over the full arc rotation, from power-up. If the problem didn't vary with temp (or operating time), I'd suspect it was due to a problem with the encoder aperture disc. The encoder module is sealed up pretty well, and disassembly of the boards from the front panel is required for encoder removal, so I haven't tried opening it to inspect the aperture disc for contamination or feathering at the aperture edges (or, possible problems with solder connections of the encoder on the keypad board).

 

This is an early production 565 , and I understand that TT later used a new/improved vfo encoder. Anyone recognize the symptoms as described, and the solution? Did the early production 565 encoders suffer from problems as described, which led to introduction of the new/improved encoders?

 

Thanks in advance for opinions or suggestions.

 

73,

Allen--W7GIF