Repairing Zenith 455 KHz IF transformer capacitors with silver mica disease
|Zenith R615 radio, chassis 6J05.
This radio had the classic symptoms of silver mica disease.
Intermittent static crashes, Changing sensitivity, beginning 10-15 minutes after turn on.
IF can AM 455 KHz.
|IF can with shield removed.|
|Typical parts layout of IF can.
This is 1st IF can, contains two capacitors.
|capacitor plate with contacts.
This is the 2nd IF can, It contains three capacitors.
|Capacitor prior to cleaning. Note the silver oxide migration bridging the clear areas in the center and outside.
Capacitor silver oxidation removed with a pencil eraser, then cleaned with Q-tips dipped in Isopropyl alcohol.
The capacitor contacts were cleaned with alcohol also.
|Capacitor after cleaning, partially reassembled.|
|Schematic of Second IF can 95-1102.|
|Schematic of First IF can 95-1101.|