tentec 1220 reversed polarity problem

[nsmeamiguel]

I bought a two-meter FM transceiver No. 1220...i got a problem about the kit during its construction at its initial stage...this is what happened...I have already constructed the Section A (Display Board Assembly) and Phase 1.0 (Display Driver and Microprocessor Circuits). All are in place and everything seems to be alright. When i did the progress test, maybe out of sheer stupidity or excitement, i reversed the polarity...there was a hum in my power supply and eventually it died down...i checked and found out my error so i corrected the polarity and put on the switch there i found out that the unit is no longer working waaaaaa!!!!!...my question is what do you think was the part or parts that went kaput....hope somebody can help me make this kit operational...thanks

[5B4AJB]

don't worry! you probably just blew the pants off the "reverse protection diode"

Look at where the power comes into the radio, follow the red track, it should go straight through a diode which is likely to be blackened or completely exploded, change this, (making sure you put the new one in the right way round) & voila!