Defeating the Auto Power-downTimer | Extron electronic MPA 152 PLUS

Defeating the Auto Power-down Timer

The auto power-down timer determines whether or not the amplifier enters standby mode. The amplifier powers down if the input signal remains below the input signal detection threshold for about 25 minutes.

The timer resets whenever the input signal exceeds the input signal detection threshold. Resetting the timer starts a new 25 minute countdown until the amplifier powers down. Resetting the timer also causes an amplifier that is already powered down to “wake up.”

There may be times when it is desirable to bypass the auto power-down timer. However, this should be done as a last resort. Examples of when defeating the auto power-down circuit might be required include:

•If the amplifier is used in a paging system. When the amplifier has already powered

down, the first syllable might be cut off as the amplifier wakes up from standby mode.

•If the input signal is so quiet that the level remains below the input signal detection threshold for 25 minutes, the timer would cut the audio in the middle of playback by

placing the amplifier into standby mode.

ATTENTION: The following procedure cannot be reversed and should be carried out as a last resort. Be certain that you need to defeat the auto power-down timer before continuing.

To defeat the auto power-down timer, follow these instructions:

1.Disconnect power from the amplifier.

2.Remove the four screws that secure the top enclosure to the bottom enclosure (there are two screws on each side panel).

ATTENTION: Exercise caution when removing the screws to avoid stripping the head.

	P	lu	s
	P	lu
A	152
A
MP

R
POWE
V
12A MAX
0.7	L

		OUTPUT
	/ 4Ω	R
8Ω	2	REMOTE
CLASSG		L
WIRIN

				C	G	A
			V	C	50m	A
	PU	TS	10V
IN	PU		R
IN			R

3.Slide the top enclosure forward to clear the switch and potentiometers on the front panel, then lift it straight up to separate it from the bottom enclosure. The circuit boards are now exposed at the front.

Four screws (two on each side)

secure the top enclosure to the bottom.

ATTENTION: Do not touch the electronic components or circuit board connectors without being electrically grounded. Handle circuit boards by their edges only. ESD can damage circuits, even if you cannot feel, see, or hear it.

MPA 152 Plus • Setup and Operation