Hi, I’m building a K4600 color processor but it’s not working.
I’m noticing two main problems:
some chips are getting quite hot when the unit is powered, in particular the 3505, 2595, 4510 and 4565 while the others are not heating up.
Another thing I noticed is that T6 is getting the sync signal while there’s nothing at its output, so I’m considering replacing the transistor.
I was wondering if the two things (i.e. chips getting hot and T6 not amplifying the sync) could be related, and if not where could I look for the cause of heating.
Excess heating indicates wrong supply voltage or shorted outputs.
Due to the complexity of this kit, I’m afraid it is almost impossible to troubleshoot it from a distance.
We can offer verification of your kit if you return it to:
Velleman Kit Tech. Dept.
Legen Heirweg 33
9890 Gavere
Belgium
chips are correctly getting 12v volts from the regulator.
edit: I replaced the faulty transistor and now the unit seems working fine,
anyway the chips are still hotter than the regulator 
It does not seem normal to me
During my troubleshooting I found a mismatch between the kit schematics and datasheets.
On the TDA3505 sheet pin 27 has a capacitor connected to ground for storage of leakage current information and rating specifications state this pin should not have external DC voltage applied.
Anyway the kit schematics show a voltage divider giving 3V to the pin.
What is the reason behind that?
Due to the age of the kit, this information is unavailable.
However, the kit has been on the market for more than 15 years and works fine as-is.