Dear Friends,
My friend blew up his UBC3500XLT due to connecting it to a 12V Powersupply.
Some smoke and a nasty smell was the result.
The damage is shown on this foto:
http://s9.postimage.org/x6ylb2vu7/UBC_kapot.jpg
I opened my own radio where you can see the undamaged components.
http://s18.postimage.org/9gxe8rde1/ubc_heel.jpg
Can anyone identify the damaged components?
What should i buy to replace the burned items?
Like to hear from you,
Regards, Rolf Pieters, Utrecht - The Netherlands.
It looks like you will need a 200 and a 100 uF electrolytic surface mount cap rated at 10 volts or more.
You could get by with standard cylinder shaped caps if space permits.
Those look to be fairly large so anyone that is competent with soldering should be able to swap them out even though they are surface mount.
The trouble is, it cannot be seen if there are burnt traces under or around the fried parts. And, there may be other fried parts if there was no voltage regulator just after the fried parts in the circuit.
Have you tried plugging in the correct power adapter and seeing if the radio will still power up?
They appear to be filter caps and if they did not short, applying the correct voltage may power that radio up.
When they fry like they did, they will sometimes create a short so don't leave the correct power supply plugged in for more than is needed to see if it still powers up. If the one smaller device is a diode, it may be a reverse polarity protection device and it may be open now,
If they are caps and you think they are shorted, remove them from the board and then try and power up the radio. Pay attention to the copper traces under them when removed and make sure it did not burn together or short to the next pad over.
If the radio has a voltage regulator (it should), the radio should still power up when the correct voltage is applied as long as nothing is shorted in the area of the burnt parts. If the one smaller device is a reverse polarity protection diode and it burned open, it would need to be replaced before the radio will power up. It could also be bypassed for a quick test as long as you apply the correct polarity and voltage but I do not advise that considering what fried the thing in the first place!
There are also some radios made that do have voltage regulators but not for ALL parts of the circuit. Things like the audio amp stage could be unregulated so you are at the mercy of the unregulated parts and if they survived the 12 volts or not.
What is the standard input voltage of an 3500? I'd guess 6 volts and the power supply your buddy used may have been marked as 12 volts but if it was an unregulated wall wart, it could have been putting out 18 volts or more depending on its current rating.
