soundcraftsmen phase control regulation pcr 800

Since the voltage is regulated at +/- 70V, it indicates that the thyristors are fired before 90°. This circuit controls the firing of the thyristors. The red box at the top is the phase control section. I can verify this because when I bench tested this PCR800 at full power into an 8Ω dummy load, the supply rail voltages stayed at +/- 70Vdc. This voltage is regulated, meaning it doesn’t sag under load.

After rectification, the output is at +/- 70Vdc. The transformer secondaries are connected at the left. Phase Control Regulation (PCR) SchematicĪt the bottom left are the four thyristors for full wave rectification. Let’s take a closer look at how this phase control regulation works. They replace the traditional bridge rectifier that is found in an unregulated linear power supply. The four shiny disks beside the power transformer are the thyristors. Removing the top cover shows the Phase Control Regulation board bolted to two capacitors hidden underneath. Soundcraftsmen PCR800 Phase Control Board And this regulation is made possible by controlling the phase angle of the thyristors feeding the filter capacitors, hence the term Phase Control Regulation. To understand this term better, it means the power supply is Regulated. What is so special about this amplifier is the PCR part, which is an acronym for Phase Control Regulation.

It was introduced sometime in the early 1980s, presumably for the hi-fi market. The Soundcraftsmen PCR800 is one of a kind.

Soundcraftsmen phase control regulation pcr 800