Re: Hacker RP25 - service sheet voltages?
Yes, it's a negative earth chassis.
Those numbers in the table aren't voltages with respect to chassis - they are voltages across legs of the transistors. So it's right that there is ~9V across the collector and emitter of T5 and T6 - together, they add up to 18V.
As well as the 5-pin connector, check all earth paths back at the chassis. Also check the power switch measures 0 ohms when closed. And that the batteries (or PSU) are good.
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