-- o ICOM

•
ASKKABOOM
Michael Geier KB1UM
7 Simpson Court
S. Burlington VT 05403
Fix or Ship?
Previous columns covered how
to fill: your radios-an important
part 01the ham experience. There
comes a time, however, when it
makes sense to send the rig back
to the factory, even if you are a
very skilled techn ician , and especially
if you're not. This column is
about determining the cutoff point
between " I can till. th is! " and
"wnere's the shipping box ?"
Technical Skill
One very important fact or is
your confidence in your ability to
repa ir your rig . With the cost and
complexity of today's rigs, you
don't want toget in over your head
and make mistakes that can result
in tremendous repa ir bills later.
This ability varies widely among
hams, and seems unrelated to
class of license. Some hams are
just more into the mechanics of
the technology than others.
Manufacturers d iscourage
owner-performed repairs, and it
makes good economic sense for
them to do so. For one thing, they
make money when you send the
rig in, unless it's under warranty.
Also, they maximize their profit by
fixing the most units per day possible.
If a techn ician has to spend
several hours wading through an
owner's botched repair job, the
company makes less than it would
if he could fill. several units during
that time. The problem is compounded
by the fact that the tech
often has no idea how to separate
the original problem from what the
owner has done to the rig!
Warranty Service
Number 24 on your Feedback card
The Tech Answer Man
such as filters, FM boards, and the
like. The basic purpose of warranty
service is to correct " infant mortality,"
or the sudden malfunction
of a new product. It is axiomatic,
and true, that a solid state device
will tend to either die within a
week , or work for years . Hence
the standard 9O-day warranty. Although
the trend is toward longer
warranties, they are a preny safe
bet on the part of the companies.
So are extended service co n­
tracts.
Fixi ng '1$ Tweaking
One thing I've found about warranty
service is that it's just about
impossible to get a radio adjusted
unless it is so far out of whack that
ply malfunction, perhaps a YOM
will do, but do you really want to
dive into a PLl problem without a
scope?
Finally, weigh your time versus
the expected repair costs. A job
that wilt take you 14 hours to puzzle
through, but may only cost $60
at the shop, is probably not worth
doing, unless you have lots of free
time (free what??), or you just
want to play with it on weekends,
in which case it will probably sit
broken even longer than it would
at the servce center!
Gening Parts
They say that in Australia, parts
are plentiful because there are
lots of electronics enthusiasts.
That's certainly not the case here
in the good old U.S.A. Chances
are that YOU'll wind up having to
order parts from the manufacturer.
Expect to get soaked. I was
recently charged $11.70 for a chip
"a new solid state
device will tend to either die within a
week, or work for years. "
it's practically unusable. As far as
manufacturers are concerned, it
either works or it doesn't. So, if
you are unhappy with, say, the
alignment of an oscillator frequency,
live with it until the warranty
runs out, and then adjust it
yourself.
The Big Decision
Now the rig is out of warranty,
and it stops working. What to do?
The basic strategy is this:
Weigh the chances of a successful
repair against those of making
things worse. This does not have
to be a purely emolional gut reaction.
You can approach it in a Iogical
manner.
Warranty servi ce from manu- First, ask yourself whether you
facturers can be very slow- you have an idea about what is wrong
wait up to several months to get with the darned thing! Sometimes
your radio back. This makes it the problem will be obvious to you,
tempting to fill: it yourself, but it and other times it will be a big
just doesn't make sense to open mystery. Even if it's a mystery,
up your rig while it's still under you can still tackle it yourself,
warranty. If you tamper with it and as long as you feel competent to
then have to send it in anyway, it do so.
will automat ically be classified as Next, ask yourself whether you
" out of warranty." You will be have the equipment to do the jOb.
charged the regular rate, even if The first order of business here is
your intrusion is unrelated to the a schematic diagram. To delve inmalfunctiOn.
to the rig without one is just asking
This doesn't apply, of course, to for major trouble. look at your test
the installation of factory options, gear. II you suspect a power sup-
74 73 Amateur Radio • June, 1989
that should have cost no more
than $3.001 Manufacturers mark
up parts very heavily. (An exception
is Yaesu. Parts I've ordered
from them have been very reasonable.}
In any event, at least the
labor (yours) is free!
Now, let's look at this month's
letters:
Dear Kaboom,
Why does the last digit on the
frequency display of my T5-130S
sometimes drift up and down,
while my friend's TS-440S is absolutely
stable? Is there some way
I can make mine stay put?
Sig ned,
Wanderin'
Dear Wanderin,'
The answer lies in the fundamental
difference between the
two radios. The older ' 130 has an
analog VFO, and the display is a
type of frequency counter. As the
VFO and/or counterdrilt, the number
wanders. The '440, however,
is a digitally synthesized rig. The
display is generated by the microprocessor,
and has nothing directly
to do with the actual frequency
01 the radio . The computer
also controls the synthesizer to
put the radio on the displayed frequency.
In other words, the TS­
130's display follows the radio,
and the TS-440 works the other
way around.
Dear Kaboom,
The middle segments of all the
numbers in the digital display on
my Kenwood T$-120S have gone
out. Otherwise, the radio works
fine. But it sure is hard to fell what
frequency I'm on; the numbers
look like something from another
planet! Where should I look?
Signed,
Half-Dig it
Dear Half,
The likely c u l p ri t i s the
TC5066BP, IC16 on the counter
board. This chip is a display-tube
driver, and it controls the middle
segment. The part is available
from Kenwood. The board is just
behind the display. Be careful not
to break the delicate display tube
when you pull the assembly to
change the Chip.
Dear Kaboom,
I have a modern digital HF rig,
and when I tune through the
bands, there's an annoying
thump in the audio every fa kHz.
It's especially noticeable on AM
signals. I called the company, and
they said it was normal, but my
cousin's identical model doesn't
do it, and his is two years older!
Are they lying to me or what?
Signed,
Thumper
Dear Thumper,
No, they're not. II you've been
reading ham mags in the last year
or two, then you've read about
phase noise in synthesized rigs.
It's a sort of modulation of the oscillators,
caused by the digital
con trol process. It degrades a radio's
performance, and the manufacturers
have been Irying to improve
the situation. The current fix
is to make the phase locked loop
tighter by decreasing the loop filtering,
and it works .
Unfortunately, it also causes
some overshoot at certain frequency
intervals, and this is what
causes the audio thump. Your
cousin's unit was made before the
mods went into effect.
Have a tech question? Send if off
to " Dear tcetxam" at the above
address. III