BX645A (Techniek Radio/TV)

door Pandu Rajan , 23.04.2024, 09:11 (212 dagen geleden)

Dear Forum members

I am in the process of restoring the above set. In this set the band switch is motorised. I am unable to understand the working of this and I need following clarifications.

1. What is the function of the switch SK7? I presume this is fitted inside the motor assembly since it is not visible from outside.

2. I am uploading the 3 pages of the service manual which gives the details of the motorised band switch. The circuit shown is when the band switch is in KG2a position. So as per my understanding for every time the band switch buttons are pressed from KG2a to MW the switch segment SK6 moves one position clockwise ( if we are looking from the front of the chasis) so that the proper band contacts are made. The motor unit has a mechanical stop when either the KG2a band or the MW band is reached. So the motor cannot move beyond these limits. Now my question is when it reaches MW band, the mechanical stop has reached, and now if I select KG2a button how the motor runs in a reverse direction to reach KG2a band? I presume the motor is 6V ac motor because the supply is given from the filament winding of the main transformer.

Regards

P.Rajan