Disclaimer: I take no responsibility for any damage or injury if you choose to perform this repair to your own radio.
The Supersound II from Pinell is a decent radio, but some earlier models are well-known for failing power supplies.
Pinell do replace faulty power supplies as long as your warranty is valid, but once it has expired you are on your own.
Luckily replacing the power supply is a simple operation!
In making this info-page I have found there to be at least a couple different power supplies used for these series of radios.
These two revisions differ vaguely, but will still require you to find the correct matching power supply for your unit.
You can tell the different revisions apart by looking at the date-codes, in addition to some design changes on the back of the radio. The oldest revision usually has a date-marking between 2010-2013. The audio-jacks are placed vertically on top of each other, like pictured below:
The second revision has a date-marking from 2014 and onwards. This model has the audio-jacks on the bottom placed horizontally, like pictured below:
You should also find and confirm the correct voltage and power draw by reading the specifications on the power supply itself. Below is a picture of the power supply from a radio which use the second value.
The replacement power supply has generally been found to have one of the following specifications
2010-2013: 12V, 500mA
2014 and onwards: 10V, 1250mA
You can find power supplies matching these specifications in your local hobbyist stores (Clas Ohlson, Biltema etc) or you can just use a spare power supply as long as it meets the specifications above. You can safely use a power supply being able to supply more current (eg. >500mA) but the voltage (eg. 12V) has to be the same. These values are usually written on the case of the power supply itself.
It’s up to you if you want to place the power supply on the inside or the outside, but for most cases leaving it on the outside is preferable. Usually people don’t have spare power supplies like the one used inside the radio lying around.
To connect the new power supply to the radio you have multiple options. You can solder the wires together, if you have a soldering iron handy. You could use a cable-shoe connector and crimp the two wires together. The very last resort would be to remove the insulation and twist the wires together, before securing them with electrical tape. I would however not consider this a permanent soloution.
If you have any questions, feel free to leave a comment below this post.