Uploaded February 2016 | Updated September 2026, 1 week ago
One channel was ok, the other channel was basically dead. Using the function switch (radio, phono, tape) showed that the problem was present in every position, that is, the problem was common to all inputs. A sine wave was fed into both phono jacks (L+R). Then both oscilloscope probes were connected right after the function switch. Signal was missing from one channel. Function switch was liberally sprayed with contact cleaner. Problem disappeared. All switches were then sprayed with contact cleaner.
One channel was ok, the other channel was basically dead. Using the function switch (radio, phono, tape) showed that the problem was present in every position, that is, the problem was common to all inputs. A sine wave was fed into both phono jacks (L+R). Then both oscilloscope probes were connected right after the function switch. Signal was missing from one channel. Function switch was liberally sprayed with contact cleaner. Problem disappeared. All switches were then sprayed with contact cleaner.
