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PA150 PCB assembly guide




The PA150 PCB is used in my BPA300 project which uses 2 PA150s in a bridged confirguration. The PA150 PCB can also be used non-bridged to provide 150W output at 2.7ohm load.

 

New PA150 PCB :

6 WIMA 0.1uF capacitors are soldered directly at the LM3886's supply pins between the +30V, GND and -30V, GND.

 

 

Parts list for 4 PCBs and hk.farnell.com parts number :

PCB parts label

Farnell HK Order Code

hk.farnell.com

Qty
Description
Mftr. & Part No.
R2, R13, R18
1160203
12
RESISTOR, 0.1%, 0805 10K
WELWYN - PCF0805R-10KBI.
R3, R10, R15
1160275
12
RESISTOR, 0.1%, 0805 200K
WELWYN - PCF0805R-200KBI.
C10, and also director solder to 3886 supply pins
146902
28
CAPACITOR, 0.1UF 100V
WIMA - MKS2 0.1UF +/-10% 100V.
C2, C5, C7
7568509
12
CAPACITOR, M/WAVE 8.2PF 200V 0805
AVX - 08052U8R2CAT2A
C3, C6, C8
498609
12
CAPACITOR, 0805 220PF 100V
AVX - 08051A221JAT2A
R7, R9, R14
1107474
12
RESISTOR, METAL STRIP, 0.2 OHM 1%
VISHAY DALE - WSR-3 .2 1% EA E2
R4, R9, R17
9353305
12
TRIMMER, 25 TURN 50K
BOURNS - 3296W-1-503LF
R1 (at the back)
9333274
4
RESISTOR, 1%, 0805 47K
MULTICOMP - MC 0.1W 0805 1% 47K
U1, U2, U3
-
12
LM3886T / LM3886TF
National
C9, C12, C11, C14
-
16
2200uF 63V Nichicon MUSE ( or use Panasonic FC)
-
R6
9333320
4
RESISTOR, 0805 5K1
MULTICOMP - MC 0.1W 0805 1% 5K1
R8
-
4
Resistor, 2 Ohm, 1W
Any brand
C4
-
4
100uF 50V
Panasonic FC
C1
-
4
10uF or 15uF 400V Solen capacitor
Solon
J2
-
4
Small 2 pin connector, pitch = 5mm
-
J3
-
4
Big 2 pin connector, pitch = 9.5mm
-
Power connector +/- 30V and GND
-
4
Big 3 pin connector, pitch = 9.5mm
-

 

You don't have to use the same brand as I used, feel free to try your favorite components.

 

Connection diagram for a 150W - 3x LM3886 paralleled amplifier, showing single channel:

 

 

 

 

Connection diagram for a 300W - 6x LM3886 bridged-paralleled amplifier, showing single channel (click for full size image):

Note : The positive balanced output is connected to one PCB and then output to the negative speaker terminal. This is because the PCB is a inverted design, so the signal is inverted at the output.

 

BPA300 Building TIPS :

  • Use 3 LM3886s with the same printed code (don't know if it is date code or lot number)

  • You may not be able to adjust the DC offset of each LM3886 output to zero, It is ok. BUT you have to make sure all 6 LM3886 to have the same DC offset (9mV in my case) so that you won't have current flow between the 3886s and there will be no DC offset at the speaker terminal.

  • Test each non-bridged board before bridge them together.

  • Test the DRV134 board working ok before using it for bridging.

  • Since there are more ground connections in the BPA300, please be careful to avoid ground loops when you layout the boards in the case. Otherwise you will get hum.

  • To avoid ground loops - use star ground, short cables

  • Tightly twist all wires

 

 

 

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