Mystery PA with Sanken transistors

[Maarten]

Originally Posted by Studio263

Those dates just show at what point the cable type was approved by some certification body or other (is there a BS number nearby?), not the date of make. You could say that the unit can't be any older than this, but it may be considerably newer. It looks early to mid 80s to me.

The 9 on the output transistors seems to confirm 1979. I can't explain the N, though, since month codes only count to L. I don't think it's much newer than 1979 given its construction and appearance.

[Maarten]

Originally Posted by suebutcher

The output transistors, Sanken 2SD257, have the code 9 N, the power transformer's marked UP 15H PT OE, the output transformer is marked UP 15 OPT OD with OE stamped on the top, and the mixer board says PRC HDK S6837 (and possibly more, there's components in the way.)

UP 15 may be a reference to the design or the OEM type designation, but found nothing on that yet. The H might mean high range (240V) but that's a guess. PT and OPT would of course be Power Transformer and OutPut Transformer. If OD and OE actually start with the number 0 instead of the letter, it might be date codes for april and may 1980 which would still be in the same range as the 1979 codes on the wire and transistors.

The text on the mixer board is quite different and might actually be from the pcb manufacturer, I suspect only a few specialised manufacturers made such boards and sold them to setmakers.