Planet Audio ZR300.4

[o. l. t.]

Amp is not getting remote power. This amp was playing just fine and suddenly cut off. It does nothing, dead as a doornail. No amp draw, nothing. I get power all the way up to the chip on the remote input side and no further.

Ideas welcome.

[Perry Babin]

It may simply be a broken connection on a component or jumper. The layout is shown on the top of the board. Follow the voltage from the remote terminal towards the 494 to see where you lose voltage.

[o. l. t.]

Originally Posted by o. l. t.

I get power all the way up to the chip on the remote input side and no further.

Right there. Input pin 1 I suppose of the chip is where the remote power stops. It was once suggested a capacitor may be to blame since these chips rarely fail, but the idea went no further.

[Perry Babin]

Post the voltage on all 16 pins.


Pin 1:
Pin 2:
Pin 3:
Pin 4:
Pin 5:
Pin 6:
Pin 7:
Pin 8:
Pin 9:
Pin 10:
Pin 11:
Pin 12:
Pin 13:
Pin 14:
Pin 15:
Pin 16:

[o. l. t.]

Hilarious, all I have is paint on this computer. Pathetic looking ain't it?

The one pin that shows 1 volt rises from zero to 1 volt over the first 30 seconds the amp is on, the others are dead except where it is marked 12 volts.

[Perry Babin]

I posted the list so you could copy and paste and fill in the blanks. If you don't know the pin numbering scheme, see attached.

It appears that the IC is defective or something is dragging the 5v regulated output to ground. Pin 14 is the regulated output and should have 5v on it.

As a side note... If you need a better program for drawing, download Open Office (free) and use the 'Draw' application. It's not great but it's MUCH better than paint.

[o. l. t.]

Pin 3 has 1 volt on it, but must rise from zero over 30 seconds to get there.

Pins 8, 12, 11 all have 12 volts on them.

What part number readily available would replace that chip? That one is a booger to find.

[Brain Fried]

Originally Posted by o. l. t.

Pin 3 has 1 volt on it, but must rise from zero over 30 seconds to get there.

Pins 8, 12, 11 all have 12 volts on them.

What part number readily available would replace that chip? That one is a booger to find.

The TL494? i am not 100% ask perry to make sure.

[Perry Babin]

Yes. A TL494. Mouser doesn't have the 494 but they have the 594 which is essentially identical. Click HERE.

[o. l. t.]

TL494

If one of those will work just point to it I don't know all the different designations of each chip.