Sundown prototype

[mike49504]

Not sure what kind of amp this is but a guy told me it was a sundown prototype..

I dont believe the amp is powering up since the power light is not lit when power is applied..

Heres what i get on the 494

Pin 1:0.92
Pin 2:VOLTAGE IS PULSING
PIN 3:0.06
PIN 4:0.06
PIN 5:1.44
PIN 6:3.59
PIN 7:0
PIN 8:0.71
PIN 9:0.10
PIN 10:0.10
PIN 11:0.71
PIN 12:13.71
PIN 13:4.95
PIN 14:4.95
PIN 15:4.18
PIN 16:0.01

[Perry Babin]

Post a photo of the inside of the amp.

[mike49504]

Heres some pics of the amp

[mike49504]

Any ideas on where to start checking since the amp is not powering up?

When tracing the gate leg of the power supply fets back they connect to Leg 1 of a couple of C1023 transistors then go thru a couple resistors then to pin 9 of the 494.. I only get 0.10 volts on pin 9 of the 494 ..

[timwebb]

ive never seen that design before. i would pull those transistors out in the power supply and start there.

[mike49504]

Im going thru the power supply right now and pretty much rebuilding it due to further inspection some has jumped traces ect..

I cam across a C102 transistor..

In diode check this is what i get does it appear to be ok or defective ?


Legs 1-2:OL
Legs 1-3:OL
Legs 2-3:OL

Probes reversed

Legs 1-2:1.034
Legs 1-3:OL
Legs 2-3:OL

[Perry Babin]

Find out why pins 8 and 11 have no voltage. They should be near 12v.

[brandes.cm]

That layout is close to Diablo Audio Technologies 2500.1. Which the schematic for a sinuslive A500 is close.

The larger transistor off the row of small caps supplies power to pins 8, 11 and 12 on the TL494.

Sent from my Punch 60.2