STK463

The STK463, STK-461, and STK465 are a group of Stereo Amplifier ICs with the same pinout and manufactured by the Sanyo Corporation. If you are looking to understand the equivalent and pinout, then the STK465 article might help as well. This article might also help prospective buyers determine what a genuine IC looks like, because there are many fakes coming from the Far East.

These thick film hybrid ICs use Insulated Metal Substrate Technology (IMST) for AF power amplifications. This special technology allows the construction of electronic circuits on an aluminium metallic substrate. The power transistors such as the Darlingtons are usually in bare die form with aluminium wires connected to them using ultrasonic bonding.

This is a genuine factory-fitted STK463 package. These photographs might be useful for comparison purposes if you need to check if the "new" replacement IC is genuine or a fake.

This Hybrid IC came out of an amplifier where one channel was operating and the other was not. The amplifier protection circuitry was not detecting a short and therefore it was not going into protect mode. This type of situation can happen if one of the power transistors for one of the channels was open.

Looking at the inside of the Hybrid IC, we see that it has four power transistors in bare die form. Each transistor has a pair of wires bonded to them and the main board. However, if you look closely, one of the transistors wire is broken indicating that there must have been a short; part of the wire melts as a fuse would. Checking the transistor with a meter indicated that it was still functional, and therefore re-establishing the connection should bring the IC back into working condition.