Hi Matti!
My Juma TRX2A –project is in such status that I have switched it on.
DDS card is up and running nice. I met problems when I tested voltage supply in Main Board.
Based on Juma Manual I measured voltage levels over capacitors C65, C63 and C64. I am supplying Juma with accumulator which pole voltage is 12,1V.
C65: U=11,8V (instruction values 12V...15V) – this is ok from my point of view.
C63: U=8,6V (instruction values 4,8V...5.2V) – here is over voltage.
C64: U=1,0V (instruction values 9,5V...10,5V) - here is under voltage.
I measured also input voltage to the regulators 1 and 2 (LP2951). I both cases it is 11,8V in pin 8. Is it possible that these both regulators could be defected?
How I could check if the problem is in regulators or in somewhere else?
Before I was able to place this question to the Juma Forum, I got hint to check capacitors above and resistors R31, R66 and the position of regulators 1 and 2.
I did these inspections and soldered pins of regulators and installed C64 ones again. Regulators are installed in correct position. But, measure results over C65, C63 and C64 were the same again as before!
The only what I am thinking now is to change the regulators. Now I am handless how to continue with error fixing?
73, Saku OH2NOS “JA”
Ps. “JA” = Juma Addicted