Re: QCX S/W 1.04, PCB Rev 5, 40M Band : Looking for a diagnostic insight #qcx #40m


ajparent1/KB1GMX
 

The audio system is DC coupled so any error always start at the input and
progress to the first error point.  If the voltages are off it will not work well.

With a common every day multimeter measure the junction of R1 and R2.
It should be 2.5V (pllus or minus a small amount).

IF not make sure the right resistors were inserted and check soldering.

IF Good then test pins 7 and 9 of IC4, if the same as the first measurement (2.5V) your good.
If not solder the leads of T1.

Go to pins 2,3,5,6 if IC5, the voltages should be exactly the same to the limits of
your meter (+-1 digit).

IF good then proceed, if not check your assembly, likely soldering.

Check IC 5 pins 1 and 7 they should be the same votlage and around 2.5V.

IF not are, same dance check your work and soldering.

IF they are we can talk later.

One last thing make sure no resistors are resting against another part,
no solder whiskers causing a short.

Also make sure the Volume pot, three leads actually connect to the board!

Enough for a start.  No scope needed yet.

Allison
-------------------------------
Please reply on list so we can share.
No private email, it goes to a bit bucket due address harvesting

Join QRPLabs@groups.io to automatically receive all group messages.