Re: QCX 40 NO POWER OUTPUT #problem #40m #qcx40


Greg Walters
 

I don't know why that sent already...


OK. I posted this once with a few measurements using the on board test equipment the other day. 

Tonight, I began to go over it again taking all measurements, again with the on board test equipment. I began to get weird readings, so I broke out my Fluke 77III and checked those voltages again. They were definitely off. I checked Clk1 and with the on board it was varying, but went to 0 after I keyed up. It wouldn't show voltage again until I turned the radio off then back on again. With the Fluke, after keying up without using the on board first, the voltage stayed steady at 1.7, but if I checked it with the on board, it would read 0 just the same after keying. 

For example, Clk 0 on the on board, was varying between 1.53 and 1.81. On the Fluke, it was rock steady at 1.70. So, I used my Fluke to take all the measurements listed below. 

I will list them as they are on pages 128 and 129 of the manual. 
Here are all the measurements. This is with a power supply at 12.72 volts. 

Clk0--1.70
Clk1--1.70
C2--3.40
D2--4.95
T1 pins 1,2.3, & 4--0
T1 pin 5--2.53 
T1 pin 6--2.52
T1 pin 7--2.52
T1 pin 8--2.516
C43--2.516
C44--2.521
C45--2.521
C46--2.518

IC5
1--2.554
2--2.523
3--2.52
4--0
5--2.521
6--2.525
7--2.597
8--12.30

IC 6
1--2.594
2--2.593
3--2.593
4--0
5--2.594
6--2.596
7--2.596
8--12.30

IC7
1--2.549
2--2.550
3--2.551
4--0
5--1.552
6--1.553
7--1.553
8--12.30

IC8
1--2.527
2--2.527
3--2.506
4--0
5--2.537
6--2.552
7--2.552
8--12.30

IC9
1--4.74
2--4.74
3--4.71
4--0
5--2.493
6--2.508
7--2.509
8--12.30

IC10
1--6.17
2--6.17
3--6.17
4--0
5--6.13
6--6.13
7--6.17
8--12.30

LCD
1--0
2--4.89
3--0.78
4--4.85
5--0
6--0
7--4.88
8--0
9--4.88
10--0
11--0
12--4.87
13--0
14--0
15--4.96
16--0

Some measurements are dead on, some were slightly off and others were wildly off. Particularly IC7, 8, 9, and 10. Then the LCD is off oddly, but still works fine. 

There is no RF at Q1, Q2, or Q3. 

Is the radio dead? Do I need to scrap it and buy/build another one? (I don't mind, I love building these things.)

Any help to revive the radio would be greatly appreciated, if it isn't dead. 
--
73,
Greg
KY4GW

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