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• 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
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