Specifications

AMP2-T assembly instructions. © 41Hz Audio / www.41hz.com Revision 1.0T boards
ii. The HMUTE output can be used to control speaker output relay, via a
driver circuit. The HMUTE will go high (+5V) in case the amp is muted
or in case of over current, over/under voltage and other errors. Shorted
outputs or shorted output transistors would also trig the over current
sensing. If no errors are detected and the amp is unmated HMUTE will be
low (0V).
f. Connect the MUTE input (J2 pin 11) to +5V (J2 pin 8) in a manner that the
MUTE signal can be shifted from +5V to ground (J2 pin 5, 6 or 7).
g. Switch on the +5V supply, but not the main rail voltage yet. The +5V should
draw about 25 mA. If a LED is connected to J2 pin 9, it should light up. If a LED
is not connected, check if there is +5V on the J2 pin 9.
h. Now, switch on the rail (main) power supply. It should draw a current of about
1mA.
i. Shifting the MUTE input from +5V to ground will toggle the amplifier from mute
to active. Now the amps should go active, and the +5V should draw about 50mA
and the LED (or J2 pin 9) should go low/off. If it does not, this indicates the
amplifier is still muted, for example because the voltage is too low or high or
current is over limits (shorted outputs…) If this happens, shut off the power,
dischargen the rail capacitors with a suitable resistor. Check all soldering and
everything else in the previous paragraphs. Do not proceed further until this
testing stage has passed successfully.
i. Note that under-voltage protection has a 200 mS delay and is non-latching
and the amp may “instantly” turn on again when the voltage recovers, and
then go on-off-on-off several times per second. In that case, turn the power
off!
ii. Note with the supplied voltage sense resistors, R112, R113, R114 and
R115, the lowest voltage the amplifier can be operated at is about +/-34V.
At lower voltages, the amp will not leave the mute state.
iii. Note also that the current sense (0.01 ohm) resistors must be in place for
this test to work.
j. When the amplifier is un-muted (LED is turned off), the positive rail should draw
a maximum of 40-80mA. The negative rail current may be 150-200 mA.
k. If everything looks OK, then power down, remove the current limiting resistors,
and proceed as described below.
9. Mount and solder film and ceramic radial lead capacitors.
a. There are two types of 0.1uF 250V film capacitors. C3 and C4 are rail to rail
mounted to reduce ripple on the DC supplies. These are Panasonic polyester caps
in a brownish dipped casing. C8 and C10 are part of the output filter and remove
high frequency ripple from the speaker outputs. A 100V rating would be
sufficient here but the 250V give a higher high frequency ripple voltage margin.
b. There are also four 100V 0.1 uF decoupling capacitors on the power rail; C1, C2,
C11 and C12.
10. Mount and electrolytic capacitors. Respect the polarity as marked on the PCBs.
a. There are two high ripple, low ESR bulk capacitors; C29 and C30. One on each
rail to ground and rated 100V. The C6 and C7 are rail to rail and therefore rated
160V.
b. C100 and C200 are the input capacitors. There are 1uF electrolytic Panasonic FC
capacitors are supplied in the kit. These are good quality standard capacitors.