help with this simple circuit board

[kevinkhan]

I have an American DJ Dual Gem Led disco light which is faulty.
When i power on the unit all the led lights turn on and dont change or go to the beat of the music.

Initially the voltage regulator broke off so i replaced this with a new one.

Attached is a circuit diagram for an American DJ Dual Gem Led disco light and also a picture of the printed circuit board front and back.

Any help would be greatly appreciated.

Thanks

 

[KeepItSimpleStupid]

generally, you would look at the +5 voltage and measure the ripple of the power supply. the problem is the processor will die if the voltage goes over 6 V or so. On PDF page 235 is the Absolute max ratings: [url]http://www.atmel.com/Images/Atmel-2486-8-bit-AVR-microcontroller-ATmega8_L_datasheet.pdf#page=235[/URL]

I'd use a scope to check the crystal activity and i's look at the I2C bus for activity as well.

The one thing, you might be able to check is (MIC) with respect to Vcc. See if there is any AC sort of voltage there with a signal.

Look at the voltage between pin 2 and 3 of U4A. It should be "close" to zero.

 

[alec_t]

If using or making measurements on this board, be aware it provides no mains isolation so is potentially (no pun intended) LETHAL.
There is a component labelled 'Re 10k' apparently missing from next to the heatsink and fat cap C6.
Diodes D5 and D8 have some crud at their ends. Have you checked them (also D6, D7)?