K8060 Heating up fast

Kits Audio Hi Fi Projects
1

Hi, i have a problem testing the K8060 kit.

When i turn on the power the resistors R19 & R20 and the transistors T7 & T8 are getting hot in less than a second,
also the Transformer gets warm. 1A Fuses between the Transformer and the power supply are melting (1,6A not).
A measurement on R19 shows me ~200 mV. The LED lights. The bias is fully turned left.

I am using the RKT120.30 2x30V 2x2A Transformer. http://www.reichelt.de/Ringkerntrafos/RKT-12030/3//index.html?ACTION=3&GROUPID=3321&ARTICLE=15265&SHOW=1&OFFSET=16&
The data sheet on it says: Sek1: Red-Yellow, Sek2: Blue-Green; and i have ~32V on each.
Between Red & Blue i measure ~3V and the same between Green & Yellow.
So i put Red on AC+, Yellow on AC-0 and on the other side Blue on + and Green on 0 (As u see in the picture below).
When i switch red with yellow and blue with green the error remains.

I first thought there must be a bridge between solders where it shouldnt be so i checked all solderings multiple times and all looked good.
Then i checked the transistor postions. All at the right place and right direction. The hole assebly seems to be right.
I just cannot find the problem. Do you have any ideas ?

Amp + Transformer: http://www.fotos-hochladen.net/uploads/20140521174wonth9sml2.jpg
Amp Solderings: http://www.fotos-hochladen.net/uploads/201405211742b7p51xrjt.jpg
Amp Assembly: http://www.fotos-hochladen.net/uploads/201405211749pcevu2bio.jpg

2

A couple of issues:

The power transistors and the sensor transistor are not in contact with the heatsink -> this will lead to troubles.
Make sure the power transistors are not swapped.
Most likely, the power transistors are already defective.
For best results, we recommend to replace all semiconductors in the drive and power stage.
Sorry, the quality of the pictures does not allow us to check for other errors.

3

Thank you for your fast response.
Before i order new components, is it right that T4 & T6 are both BC547B Transistors ?
My manual says T6 should be BC547 without a letter after the number.

4

Yes, ‘B’-types are OK.

5

i replaced all transistors and also connected the power/sensor transistors to the heatsink.
Nothing changed, R19 & R20 and the power transistors heating up fast.

Then i bought a new K8060, soldered it identically and …
… this one is now doing a great job in my 40l BR-Box with a Visaton W200S Chassis