EBay TDA7492 amo, no sound

[LazyH]

hello everyone. I just made a purchase of a few TDA amplifier boards from a chinese based ebay seller, it included a few 100 watt amps and one 50*2 watt amplifier. now the 100 watt amplifiers sound great and worked with no problems when run from a center tapped 25.5volt transformer from radio shack, I tried running the same transformer at it's rated 25.5 volts as per the sellers instructions with the 50 watt board, with a rectifier circuit as the board only accepts dc, checked and double checked the wiring, speaker impedence (only 8 ohm with 24+ volts)and the sound source (my pantech phone) but no matter how I hook up the system there is not a single note of music coming from those speakers. I've tried both powersource, speakers and phone with other amp boards and they all work fine, the only sign that anything is happening when I use the 50 watt board is a slight hissing sounds that starts when I unplug the power source and slowly fades away, no hissing when power is applied, only after the power is removed, I tried double checking with my multimeter, exactly 25.4 volts, right polarity, everything's working as it should with that transformer, but one thing did pop up, when the transformer is attatched to the amplifier with power running through it and I measure the voltage across the terminals, it jumps all the way up to 40+ volts, how is that even possible? I tested the transformer on its own and it should only be capable of 26 volts at most even with a power surge it shouldn't double like that, what could be causing this problem? Please, any help would be greatly appreciated. The amp is from here TDA7492 High Powe Digital Amplifier Board 50W 2 100W Can Parallel Bridge New | eBay

 

[polop1]

I am using a TDA7492 based amp, mine is one from sure. I had similar problems, are you using the 3.5mm jack as input? On mine I needed to bend the jack significantly to make it work well. For now I am using a hair band to keep the pressure, though once my dac gets here I will switch to using the phono inputs.

Edit: note the link you have is broken.

 

[LazyH]

Mine doesn't have a 3.5 jack on it, just solderable wires, red white and black. I hooked it up to a more regulated power supply, 18 volt laptop power supply and it works fine, maybe unregulated it didn't have the right voltage. It sounds to me like you could fix by soldering on a new jack, it's not the solder joints themselves that are broken are they? I had a scoche fm car transmitter that had a jack in it that was always crackling and muting, I actually had to desolder it and bend the terminals inside to get a connections,unfortunately most jacks don't have rom for you to poke around in them like that one did.