[MRCA] Germanium diodes

[J Forster]

I have no experience w/ this set, but if grease is stiff, the servo motor may not start turning until the error gets large and then it will break free on overrun the null...  essentially similar to a limit
cycle oscillation. It often happens in small servo systems.

The motor itself is likely oiled, but the gear train may be greased.

Just a though,

Best,
-John



Doran Platt wrote:

> J Forster wrote:
> > Are you sure sluggish operation at lowered voltage is not due to drying out grease. Generally the torque of motors increases with supply voltage, and dried out grease would need more torque to operate.
> >
> > It is possible older diodes may deteriorate. Can you do a V-I plot on a curve tracer. I'd suspect they are more likely to go leaky than anything else.
> >
> > FWIW,
> > -John
> >
> >
> John,  Point taken, however I don't think that motors are the issue,
> here.  The ones used are the smaller, sealed type units that were
> checked at the last depot overhaul in 1984.  They also appear to run
> just fine.  Its the fact that the servo system hunts a lot and/or passes
> over the resonant point until the error voltage is sufficiently large to
> try and re-tune.   The TM relates this situation to, among other things,
> lack of sufficient error voltage being developed and/or error voltage
> symmetry.  I hope it diodes.  One doesn't see spare servo motors too
> often.  I don't have a curve tracer, per se, so wholesale
> resistance-matched diode replacement may be indicated, again per the TM.
>
> de K3HVG
>
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