Had to fix my TS440SAT, cracked solder joints on a transistor
 

Was Q37's leads to the IF circuit board. Somehow it
developed circular cracks in the solder joint from
the leads to the board. It kept the rig from going
into transmit. It was just a control line level
shifter or inverter.

Oddly enough I had just finished installing a new
wire dipole strung between trees on my house's
quarter acre lot. Something vaguely resembling a
80 meter dipole with a W2AU balun at the feedpoint.
I thought that I somehow toasted
the xmit part of the rig with a bad antenna, but the
rig has self protection circuits. I don't think bad
solder joints on a control line transistor would be
caused by a new antenna.... :-)

Just curious, had the rig ever been used mobile? I had my TS690 mobile
for a while and saw how badly it shook around and pulled it out and put
it back into home use, sitting on a nice and stable table with no
astronaut crippling g-loads. I like the rig too much to have kept
beating it up in the truck. I bought a much smaller (thus easier to get
solid mounting) Yaesu 857 for the truck and it seems to fair much better
than the large (heavy) Kenwood did in that environment...

Scott
N0EDV


Robert Casey wrote:

Was Q37's leads to the IF circuit board. Somehow it
developed circular cracks in the solder joint from
the leads to the board. It kept the rig from going
into transmit. It was just a control line level
shifter or inverter.

Oddly enough I had just finished installing a new
wire dipole strung between trees on my house's
quarter acre lot. Something vaguely resembling a
80 meter dipole with a W2AU balun at the feedpoint.
I thought that I somehow toasted
the xmit part of the rig with a bad antenna, but the
rig has self protection circuits. I don't think bad
solder joints on a control line transistor would be
caused by a new antenna.... :-)


--
Scott
http://corbenflyer.tripod.com/
Building RV-4
Gotta Fly or Gonna Die

Scott wrote:
Just curious, had the rig ever been used mobile? I had my TS690 mobile
for a while and saw how badly it shook around and pulled it out and put
it back into home use, sitting on a nice and stable table with no
astronaut crippling g-loads. I like the rig too much to have kept
beating it up in the truck. I bought a much smaller (thus easier to get
solid mounting) Yaesu 857 for the truck and it seems to fair much better
than the large (heavy) Kenwood did in that environment...


I got it used, so I don't know its early history. It was nice
and clean, so I suspect it had not gone mobile. I think that the
circuit board may have been a tad bit short of solder when they
wave soldered it at the factory. Not by much though. It has
always been a home rig when I've had it.

One annoying thing with the service manual is that it has the
schematics of each board, but no diagram of the interconnections
between boards. Other than a high level system block diagram.
I was going to try to back track the "on air" LED to find why
if failed to light, but couldn't find it in the service manual.
Major surgery would be required to trace it out by hand, so
I took another approach. That was to see how far the control
line "RL" signal got thru the various transistors. That's when
I found the bad solder joints.