Aug 302015
 

Bought this board as fully working for 30 euros but turned out it had a problem on the audio.

Foto 30-08-15 09 26 59

All the music and sound effects were totally disturbed and garbled.

The TA8201AK amplifier was becoming so hot that you could smell it burning.

The pcb has a lot of smd capacitors that are reknown to be unreliable but I noticed that two of them were already changed with normal ones.

I was sure that it was the amplifier shorted internally because in some occasions my 2A fuse was blown so I bought from ebay a cheap one for 4 euros.

Foto 30-08-15 09 27 34

On the left side the original one dated 1997, on the right the one bought on ebay, dated 1991 šŸ˜‰

After soldering the new one, the problem remained.

This time I decided to go for more professional approach and downloaded the datasheet and checked all the caps and resistances according to the sample circuit.

To make a long story short, the two tiny capsĀ (C28 and C29, one for the sound sfx and one for the music) connected to the input of the amp were somewhat faulty and leaking under the body.

Foto 30-08-15 10 46 45

After desoldering both of them , I noticed they were1nF each and not compliant to the suggested one of the datasheet which should be 4,7uF.

I decided to install only one cap of 4,7uF and shorted the resistances R55 and R74 to mix the sounds before the cap.

This solved completely the issues and got very clean sound with the amplifier running with a reasonable temperature.