Re: QCX-40 Microprocessor Blown?

Ronald Taylor

Hi Cory. Yes it seems there is a short on the 5 volt bus somewhere. It needs to be isolated. One quick test you can do to also isolate IC3 from the 5v bus is to use a very sharp pair of snips and cut pin 14 on top of the board (it can easily be re-soldered). You can isolate IC1 by lifting one lead of either D1 or D2. IC4 is a little tougher but I've been able to isolate it by using a dental pick and lifting pin 16 while heating it. Isolate one of these at a time till you find the culprit. Good luck.


On Mon, May 3, 2021 at 2:04 PM Cory KG7BBV <cory.goates@...> wrote:
When I turn the radio on, the 5V regulator voltage starts out at about 2.5V and then slowly drops to about 0.5V. This occurs even after I pull the microprocessor out. That makes me think I've blown some other component. The LCD screen does still light up.
Cory, KG7BBV

Join to automatically receive all group messages.