Re: [NTLK] Backlight transformer voltage

From: Adam Goddard <>
Date: Mon Jun 11 2007 - 07:17:50 EDT

On 09/06/2007, at 4:14 AM, wrote:
> Does anyone know the input, supply voltage and supply current to the
> transformer that drives the Newt's backlight?
> Thanks,
> Doug Parker
With aged backlight load: 0.58Vp-p input, 14 Ohms , 41.43mA
(calculated) 19Vp-p output, 660 Ohms, 28.8mA (calculated).
With no load: 1Vp-p input, 34Vp-p output

When looking at back of board with transformer facing you, battery at
bottom and interconnect at top:
Input comes from the bottom leg of smd transistor Q4 (D1815) to third
pin from the left of top of transformer
Other input comes from negative leg of smd electrolytic capacitor
C121 which is above Q4 and below U18.
The black lead of the backlight is connected to ground and to
leftmost pin at the top of the transformer, the read lead is
connected to the rightmost pin at the bottom of the transformer.

Do you want pictures and a rough diagram? I have my first final exam
of the semester tomorrow, but I have 6 days in between the next exam
to do a bit more schematic hunting.

   - Adam Goddard

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Received on Mon Jun 11 07:18:01 2007

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