[ARC5] Dynamotor noise in SCR-274 receivers

[Mark K3MSB]

>>Would this be a strong sign that the original chassis wiring in the
receivers definitely needs replacement?

Absolutely not!   Here's the section on Dynamotor Noise from an ATA ARA
manual (which will directly apply to the SCR-274N).

[image: image.png]
[image: image.png]

You can try the suggestion from TIm N6CC;  sometimes this works, sometimes
not.

73 Mark K3MSB

On Sun, Aug 24, 2025 at 9:36 PM Matt P <mgpaulonis at gmail.com> wrote:

> Getting closer. I completely cleaned and lubed the bearings of two command
> receiver dynamotors and get overpowering dynamotor noise in the audio. All
> three receivers have new caps and work just fine with an outboard power
> supply with 24 V AC on the LV and 60 VDC on the HV when not plugged into
> the rack. Would this be a strong sign that the original chassis wiring in
> the receivers definitely needs replacement?
>
> Matt
> W2NS
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