sony: ICF-5500M; Captain 55: Battery Meter

The control panel suggests that the meter is VU (audio level) or Tune/Batt. However I can't see by schematic or operation how it shows battery condition. A clue may be that the meter rests at right with power off or batteries removed. I'm not convinced the schematic is correct on meter wiring, looking at how VU works. Or I'm confused.

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The VU-meter works from left to right; right being the strongest signal. The battery-meter the other way around, from right to left; left being the fullest battery. It is indicated on the meter by the fat line. In the fat aerea the battery-strength is sufficent. If you use a variable powersupply, and you switch from 4.5 V to 3.0 V, you will observe how the meter goes from 'good' to 'bad'.

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Thank you!

I can see now that on any band with no signal, on RF level rather than Audio level, with the batteries getting lower, several weeks use, that the needle no longer rests on zero but near edge of fat part. Plugging in the 4.5V PSU of the Sony ICF2001D makes needle go to zero. No doubt the user instructions explain this, but online I only found a service manual. I then tried with variable PSU (centre of power jack is negative, barrel is positive unlike newer equipment).

Curiously with jack plugged into "DC Out" (lowest socket, presumably to turn on a recorder or power a MPX decoder?) the meter goes to full scale (i.e. the normal off position). A most unusual arrangement! In VU mode the meter is simply driven by a pair of diodes implementing a peak detector across the secondary of audio out transformer.

So with no signal at Tune/Batt position, the lower scale is battery condition with:

• 0 on top scale about 4.5V
• End of fat part about 3.4V (about 4 on top scale)
• Separate pip is 3.0V (about 6 on top scale)

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