CAudio Pulse2x1100 free download

File name CAudio-Pulse2x1100 pwramp.pdf

Pulse P2X1100 circuit description 1. 2. 3. 4. 5. switching power supply power amplifiers protection frontpanel & flashing lights PIC and system protection 1. Switching Power Supply Mains voltage is inserted via filtered IEC CN3. Earth is connected directly to chassis from the body of CN3. Live passes through fuse F2. Live and Neutral pass though a further filter consisting of C2 (X2 rated), L1 - a common mode choke - and C15 & 14 (Y2 rated). Live passes through the soft-start system, TH1, R14 and RLY1. R14 limits the initial current surge caused by the primary reservoir capacitors charging up. TH1 protects R14 if a fault causes excessive dissipation in R14. RLY1 shorts out TH1 and R14 when the PSU is running. Live and Neutral then pass to bridge rectifier BR2 which, for the 230V setting full-wave rectifies mains, smoothing performed by reservoir capacitors C22,23,44,45,32,33. In the 115V setting, this power supply is configured as a voltage doubler. Thus, the High Tension (+HT) DC generated is approximately equal for 230V mains and 115V mains. This will result in about 320Vdc between `LIVE GND' and +HT. `LIVE GND' is named as such because it is not isolated from mains but it is the reference point for the PSU. If you need to stick a scope probe around the primary side with the unit plugged in you must connect mains via an Isolation Transformer. Without this, at best you will only trip your RCD breaker, at worst you or your scope may not live to regret it. Do not forget that 320Vdc is still pretty shocking whether it is isolated or not. R36 and R37 ensure proper voltage sharing of the reservoir capacitors. Power for the switching controller circuit is provided from two sources. At start-up, the power comes from R93,113, ZD2, D22 and C75. C75 is charged up to about 47V through D22 from Zener regulator R93,113 and ZD2. The command to start the PSU comes from the PIC (+5V for off, 0V to switch on) via R33. The LED in OPT1 is turned on which turns the transistor on, shorting out pins 5&4. While the transformer windings are cooler 0 than 120 C the thermal cut-out (TX5-B) will be a short circuit. So R166 will be connected to the top of C75 and will form a Zener regulator with ZD9. The output of this zener regulator is buffered by TR49 which then powers the switching controller circuit. C75 stores enough energy to run the controller for long enough until the second source of power is ready. The second source of power comes from the transformer on pins 3 and 14. This secondary is voltage doubled by C82, D29,31 and C74 and produces about 48Vdc on VAUX. This is connected via D32 to the top of C75 so the controller circuit can continue running. VAUX is used to directly power RLY1 to short TH1 and R14 out while the PSU is running. The circuit comprising R165,R172,ZD10,R178,TR47 and R180 shut down the PSU when the voltage on C75 falls below about 32V. while the voltage on C75 is greater than 32V, TR47 is switched on and pulls pin10 of IC6 down to 0V which `en