[Abbazz]

Your TTL Prism is the version 2.0 with a GaAsP meter cell (the first version had a CdS element). The very detailed "étude" (study) published in 1983 by the French magazine Phot Argus had a lot of technical details regarding the Pentax 6x7. It is available online here: https://galerie-photo.com/manuels/pentax-etude.pdf

It's obviously in French but there are a lot of useful illustrations (including a superb exploded view of the camera) and it should be possible to use Google Lens to translate the useful bits into almost any language.

The TTL metering circuit described on page 4 is the same as yours with three potentiometers:



The text beneath says: "The circuit board features two inegrated circuits (one for measuring purposes, the other one being an operational amplifier for processing the current delivered by the sensor), three adjustment potentiometers (to be used only for maintenance by an approved service center) and a few discrete components."

So my advice is that I wouldn't try to tamper with these potentiometers.

Cheers!

Abbazz

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Last edited by Abbazz; 02-26-2023 at 10:04 PM.