Audio Amp problem

My first concern is where have you sourced your TDA1558Q devices from? These are just the sort of parts that now the ic is officially classed as being Obsolete are being offered via ebay to the hobbyist at very reasonable price however the are so often just fake bad parts! Some other questions: Have you used a PCB to mount the chip upon & what mode are you using it ie stereo so the each the LH & RH speaker bridges pins 6 & 8 plus 12 & 10 or another configuration? What’s your supply voltage for Vp & how are you powering it? The 6Vdc appearing on the outputs is concerning. Do you have access to an oscilloscope?

For any troubleshooting, even though this is a very simple configuration to replicate if is a home-built project I would verify for a “human error” first. The questions are the following: considering the data sheet (May 1992) issued by Philips as the reference, what configuration did you choose?  Is it the stereo one on page 8 or the Quadro output one found on page 9? How did you put it together? you’ve etched your own PCB, (point to point) bug style, vero-board or just a simple breadboard for experimenting first? What’s the applied voltage level? Make sure you didn’t somehow mix up the PINs (easily done). Also, if you choose the stereo configuration make sure you don’t try to mistakenly connect the speakers to the common ground or measure the output voltage that way. How did you measure your input and output voltages? With a simple voltmeter or an oscilloscope? PS: Multiple pictures showing the setup as well as measured results (in action) always helps.

I’m using the stereo configuration and I’ve built it exactly like the one in the datasheet with no changes. Also I have 3 of them 2 used ones from a radio and one brand new that I just bought from a local store that they sell good parts. So I measured the input with a multimeter to ground and I get a 2V. I’ve tried to separate the input ground to the supply ground and it draw 4A almost like a sort. I used a linear power supply with a voltage regulator similar to the one that MR C made on video 39 at 14.8V out with no problems and I’ve also tried it with a 12V commercial supply. I’ve used this configuration on a board that I made from a blank board and I’ve also used it in the breadboard they both behaved the same. I’ve checked it many times and rebuilt it many times to make sure everything is just like the datasheet with no sort or bad cables. I plugged it in with an amp meter and it differs from 800mA to 1.1A every time I power it on which is strange for me at least. Tommorow morning I’ll post pictures of the new measurements.