I picked up a T1 that
someone built at a rally a while back but was stated to be not
working cost me £10. If really was dead I could use the L match network.
I didn't find a troubleshooting guide to
figure out what the problem is but his is what I did...
All the values, and
components 'appeared' to be in the
right place etc Resistance checks on page 15 and 22 of the manual seem fine…
Apply power (with PIC
removed) and the regulators
appear to be applying the correct voltages etc..
The section reads:
Use your DMM to make the
following resistance checks.
If the board fails any of the following checks,
carefully check the position
and orientation of all
parts and inspect the board with a magnifier for solder
bridges or missed solder
joints.
Resistance across capacitor
C19: between 137 K-ohms
and 148 K-ohms. Press S2 and confirm reading
drops to between 117 K-ohms
and 135 K-ohms.
Resistance between D3 anode
(end without the band) and
the “ –“ pad near D7 (ground) where the
black wire is attached: >
100 K-ohms (may show open
or infinite on some DMMs). Press S1 and confirm
the reading drops to between
117 K-ohms and 130
K-ohms. If the resistance is higher, try reversing your
DMM leads.
Set your DMM to diode test.
Connect the negative probe
to either end of resistor R9. Touch the
positive probe to the
following pins on J5 and verify
that the diode tester shows approximately 1.6 volts
forward drop across each LED.
J5 is the connector at
the opposite end of the control board from R9. Pin 1
is the round pin at the end
near S2. Each LED may also
light up when the test voltage is
applied (not all
diode testers supply
sufficient current to produce
light):
__ Pin 1: Red LED ___ Pin 2:
Yellow LED __ Pin 5:
Green LED
The LED do not light up.
And the diode tests fail.
Humm ... scratched head a bit and had a chat with Elecraft and this extra info helped and I include it here in case anyone else have a problem:
Also for starters I had removed the switch bord from the uPC and relay board underneath for the first set of tests.
Make sure the red lead from the battery goes to the + connection near
the
unbanded end of the 1N5817 diode at D3. The smaller round positive
connector on
the 9V battery goes to the battery terminal for this red wire. (That was fine)
The black lead from the battery goes to the - connections between the
yellow
and red LEDs. (That was fine too)
J4 is the connector on the left side of the T1 control board.
J5 is the connector on the right side of the T1 control board.
Verify the MCU has no bent pins and is fully pressed all the way down
in its IC
socket. (OK)
Do you see 6V on pin 1 of the U1 processor when the PWR button is
tapped? (use
the thumbscrew or BNC jack for ground) (Yes)
You can test this at J4 pin 3, which is the pin just above and between
the
green and yellow LED, and it is the 3rd pin when counting beginning
with the
round pin 1 of J4. U1 pin 1 and J4 pin 3 are directly connected
together.
Remember that J4 is on the left side of the control board.
Also, J5 pin 3 should show 9V to ground when the unit is off and S1
has
not been pressed. Remember, J5 is on the right side of the control
board as you
would normally face the unit. (OK)
When PWR button S1 is pressed and HELD down, J5 pin 3 should be 0VDC. (OK)
If the
MCU comes ON and is working, when the S1 button is released, after a
few seconds
- J5 pin 3 will rise back to 9V . This is when the MCU times out and
returns to
"sleep mode", and releases the /HOLD_ON line at U1 pin 5. (I will test later... and it was fine, after I fixed some things but it did not work as it should initially)
This change in voltage at J5 pin 3 and U1 pin 1 and the 6V appearing at
U1 pin
1 must occur, or something is wrong with the power up circuit of D3,
R7, C20,
Q1, R14, S1, D4, C19, U2, D4. Check all of those parts and their
soldering very
closely. Both U2 (78L06) and Q1 (2N3906) should be installed with their
flat
side facing up. (Problem #1 Q1 was inserted backwards so chopped it out and replaced it with a new component the right way around this time)
Be sure U2 and Q1 are not swapped with each other. Be
sure R7
is 120K and R14 is 3.3K.
(Problem #2 1K resistor in place, replaced with 1/4W 3.3K)
Verify all of the parts are in the correct
locations,
and are not damaged or unsolder-ed. (OK on parts spent some time going over the underneath solder connections)
Be sure D3 and D4 are not installed in reverse. D3's banded end goes
toward
R14, and D4's banded end goes toward switch S2. (Both OK)
MCU U1 must be installed with the notched end closest to the J3 remote
1/8" phone jack, or to the left as you face the main board. (Problem # 3 the uPC socket and uP were in reverse, so I flipped the uPC and T1 worked fine)
You can use an ohmmeter to check for any shorts between the connector
pins and
ground with the battery removed, and between any pins of the parts and
a nearby
connection that is not at ground. Note some connections are
intentionally
grounded. Use the schematic as a reference for these tests. You can
find an
accidental short circuit or solder bridge this way.
Examine both sides of both PCBs very closely using a bright light and a
magnifier. Look for missed solder connections, shorts or solder bridges
or
splashes, etc. Remove any excess solder and clean up any poor
connections as
needed, using Soder Wik and a Q-Tip moistened with acetone or alcohol
to clean
the PCB. (The board was cleaned up a bit)
Do you ever see any LEDs light up when the PWR button is tapped (yellow
LED), or if it is held down for more than 1 second (green LED)? (Operating as should now)
Did you verify the LEDs are not installed backwards? You can check them
for
correct orientation by using the diode test function on most DMMs. (Diodes fine)
First remove the 9V battery.
Then place the positive test probe on the anode connections for each
LED at
pins 1, 2, or 5 of the J5 connector, and the negative lead on the
common cathode
connection at either end of R9.
J5 is the connector on the right hand side of the tuner as you would
normally
face the top and front of the PCB (near R21). Pin 1 is the round pin
near the
battery compartment. R9 is near the left top edge of the T1 control
board.
Each of the LEDs should light enough to be seen in a dimly lit room as
you move
the positive probe to J5 pin 1, 2, or 5 and hold the negative probe on
R9.
