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The A6EBA chassis has another major difference to the standard AE6 chassis, namely it has the double-decker D2 board, this is a separate EHT transformer that is driven differently from the line output stage which is on the D1 board underneath.

The D2 board deals with the focus, screen or A1/G2 and the EHT on this chassis which adds to the complication wrt beam limiting etc., Sony implemented various versions of this scheme across the different sub chassis versions here, some were IC driven in similar fashion to the line stages and the main psu indeed, others used more discrete component versions of the same set-up.