Pi-Amp Rev. 6
Amplifier Power Supply
Pi-Amp Rev 6. Amplifier Power Supply Schematic
Pi-Amp Rev 6. Amplifier Power Supply Bill of Material
|Schematic Reference||Description||Quantity||Manufacturer||Stock Number||USD ea.||Total|
|T1||TRNS, 625VA, 40V, Center Tap||1||Avel||Avel Y236853||67.00||67.00|
|BR1||RECTIFIER BRIDGE 200V 25A D-34A||1||Vishay||DK 26MB20A-ND||6.35||6.35|
|CP1||CAP 12000UF 100V ELECT TUP SERIES||2||Panasonic||DK P10041-ND||15.05||30.10|
|CP2||CAP FILM 0.1UF 400VDC AXIAL||2||Cornell Dubilier||DK 338-3278-ND||1.85||3.70|
|AC1||AC Receptacle IEC 320-C14||1||Qualtek||DK Q210-ND||0.78||0.78|
|PC1||Power Cable, NEMA 5-15P to IEC 320-C13||1||Qualtek||DK Q125-ND||5.16||5.16|
|FH1||HOLDER FUSE 3AG .500"L 1POS||1||Keystone||DK 3536K-ND||1.51||1.51|
|FH2||HOLDER FUSE 3AG 2.375"L 4POS||1||Keystone||DK 3539K-ND||5.13||5.13|
|F1||FUSE 8A 250V T-LAG GLS MD||1||Cooper Bussmann||DK 283-2755-ND||1.00||1.00|
|F2-F5||FUSE 5A 250V FAST AGC GLASS||4||Cooper Bussmann||DK 283-2635-ND||0.70||2.80|
|R1||RES 3.9K OHM 2W 5% METAL OXIDE||2||Yageo||DK 3.9KW-2-ND||0.25||0.50|
|S1||SWITCH TOGGLE SPST 15A||1||NKK||DK 360-1896-ND||4.70||4.70|
- The Reservoir Capacitors (CP1) are attached to a piece of bare PCB board. The Panasonic TUP style capacitor has four sturdy prongs that are bent over to secure the capacitor to the PCB. The Bleeder Resistors (R1) are soldered to the capacitor leads on the underside of the PCB board. The PCB board is attached to the chassis, directly below the HDD mounting bracket, with four 1/4" brasss standoffs. The large gap between the two capacitors will provide space for the hefty USB type B connector required to tie the face plate USB jack to the PC mainboard.
- Power supply components are fitted to the rear panel, listed from top to bottom: Mains Fuse (F1), Bridge Rectifier (BR1) with Snubbing Capacitor (CP2), Amplifier Power Switch (S1), and AC Receptacle (AC1).
- The Four Position Fuse Buss (F2) is attached to the chassis base with #6 machine screws. The chassis ground lug is located to the left of F2. With the toroid transformer placed next to the chassis, the wiring is completed in accordance with the schematic above.
- The amplifier power switch is a high quality, heavy duty toggle switch. It is positioned at the lower left rear of the chassis to eliminate high voltage wiring to the face plate. My experience has been that the amplifier remains powered on most of time so it is not necessary to have the power switch located up front. The AC receptacle is mounted from the inside of chassis to facilitate removal without de-soldering. Inside mounting also provides better mechanical stability.
Since I had the rear panel off I went ahead and installed the two RCA jacks and the four speaker wire binding posts.
- The transformer is attached to the mounting bracket using the supplied hardware. The piece of blue closed cell foam, between the transformer and chassis, protects the windings. The toroid transformer is typically mounted flat, but in this application space is a premium.
- One small adjustment was made with respect to the transformer mounting bolt. The hex head on the bolt supplied with the transformer protruded far enough to interfere with the PC sound card. The solution was to replace it with a low profile bolt (see images in apmlifier section of this log).
- A small bracket is used to provide additional stiffness to the rear panel. The mounting screw for this bracket will also hold the audio card riser support bracket (see PC section of this log).
Amplifier Power Supply Complete.