sony: Sony SRF-M37W tuning not working - easy fix

Got two of these Sony series, both with a common issue related to broken PCB copper traces in the VT tuning section.

One being this later 2008 SRF-M37W US model, and the other is the SRF-M37V US model from 2003.

Despite the large dates interval, both share the same original SRF-M37 chassis, where the major difference being the firmware version used in the TC9329FA DTS / MCU to control and generate different RF bands.

Both units, despite separated apart by at least five years, have developed the same fault, despite showing distinct symptoms when trying to tune a radio station. One was "auto-scanning" the radio stations ignoring any input from the tuning buttoms; the other just did not tune any station. This happened on all bands.

Both had a good DC-DC converter VT at 14VDC. A few additional voltage readings made me suspect of broken PCB copper traces. A systematic continuity check did confirm the issue. On both radios the open circuit was at the PCB pads of SMD resistors or capacitors.

The easy fix was to re-solder the pads. No adjustment was needed, as the units did tune known stations at the correct display frequencies.

 

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