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Philco 37-670 Shadow Meter Woes
#19

I can only describe what I see when I look into the back of the meter (where the lamp shines). The vane is there.  When there is no power applied to the coil, it looks like a thin vertical line.  If the lamp is replaced one sees a centered narrow line on the screen (I use the trick mentioned on the Phorum of taping a piece of discarded Philco dial material over the front so that I could see the generated shadow with the meter removed from the radio).

When power is applied to the coil (0-15 volts DC) I see a dark rectangle gradually appear from the CENTER of where the vane is mounted toward the right.  There is NO symmetrical rectangle on the left  side, and thus nothing to block the light on that side.  If the projection lamp is replaced the result is a thin dark centered line with zero volts.  With 15 volts gradually applied, the shadow expands to fill most of the meter screen on the right side.  There is no shadow on the left side (now looking at the FRONT of the meter).  The left side of the shadow does not move as the voltage is increased. The vane vibrates freely if power is suddenly cut off, so I assume that the vane is not binding up.

If part of the vane did indeed break off (I do not see how that could happen) it is surely lost, since the front of the meter is open once the meter is removed from the radio. 

I hesitate to try to disassemble the meter, since it sort of works as is.  And I have not found any information on disassembly of the new style meter, unlike the extensive (YouTube) videos and photos of the old boxy style.


Messages In This Thread
Philco 37-670 Shadow Meter Woes - by davemc - 03-30-2016, 08:46 AM
RE: Philco 37-670 Shadow Meter Woes - I give up! - by davemc - 04-07-2016, 08:46 AM
RE: Philco 37-670 Shadow Meter Woes - by titan1a - 05-03-2016, 07:45 PM



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