[TenTec] How Much Damage From Reversed Polarity?

[Bert Braun, DD5XL]

doc schrieb:

> There is no visible damage to anything that I can
> see on the little circuit board to which the power
> connector is soldered.  No smell of something
> burned either.
> 
> I am looking at the schematic 4-32 in the Op Manual.
> 
> Any suggestions as to which device(s) is(are) most
> likely to have failed, please?

Check the D2 16V zener diode.
If its shorted, the relay will never close. D2 and Q2 act as overvoltage 
protection, a shorted diode will cause a overvoltage protection even 
when the supply voltage is in range.
If you are sure providing the right voltage, you may simply cut off the 
diode. If it was faulty, the TRX will work as usually without the diode, 
but overvoltage protection is disabled, so be careful with your power 
supplies!


73 de Bert





73 de Bert