HFU HF Underground
General Category => General Radio Discussion => Topic started by: SHORTY on March 12, 2016, 1934 UTC
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My ICOM R71A works a little sort of doesnt smoke. Needs work ICOM says no parts can't fix. Is this of any value or should send it for a dirt nap?
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There are some shops that will service these yet.
Also, what seems to be wrong with it?
Also, there are faq's on the r71 that can help pinpoint the issue;
http://www.w0btu.com/files/misc/Icom/IC-R71A/
http://www.w0btu.com/files/misc/Icom/IC-R71A/IC-R71A%20Mods%20&%20Service%20Info/ICOM%20IC-R71A%20Technical%20Knowledge%20Base.txt
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It's hard to say Shorty. I'm not intimately familiar with the R71A circuit so I don't know if its loaded with ASICs. If it is, then you're shut down before you start because only a certain number of them are produced and when they're gone, they're gone. However, the 71A was a mid 80s unit and might have been designed completely with industry standard parts. Even so, parts can be a real bugger to locate some 30 years later. Josh said that some shops are still servicing these units. I would recommend that you find one and ask them about it. Any shop that is willing to repair a R71A has probably already sourced the hard-to-find stuff. A few years ago I slipped my Drake R8 in for factory service literally weeks before Blonder-Tongue took over the Drake repair facility. Although I love the R8 and have had a very happy 21 years with it, I know that when it eventually zorches out this time I will be giving it a decent burial and buying a good SDR. The R8 will not have owed me a thing, but a sad day nonetheless...
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I have an R71A, I am pretty sure it is mostly off the shelf components, not sure about the microprocessor (remember the R71A uses a battery backed RAM that also has programming for the CPU, so if that goes, you lose use of the entire radio, not just the memories). You can get the service manual for it online, do you know which component(s) need to be replaced?
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ASIC's aren't that hard to find. You'd be surprised what you can find on ebay. C-QUAM IC's have been out of production for close to 20 years, but they are still on ebay :)
There is also the notion of picking up a second unit as a 'parts kitten'.
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Thanks for the info guys. I'll do a internet search. I got my work cut out for me.
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I wouldn't pretend to know anything about that radio, and the problem could be anywhere given the complexities.
But if nobody will touch it, it's worth a shot to just take it apart and poke around using low tech methods that many times will work.
The links posted by Josh point out failure of capacitors do occur on these units. It states that failed ones will be discolored so they will be visual. Dried out or shorted caps are a common problem in vintage units , so common it's a great place to start. The power supply will have larger ones although they will be throughout the sections.
They are very low cost and not all that hard to switch out.
Another thing to keep in mind is MOst Likely, only one small and low cost component has failed . Ok laugh, but just keep telling yourself this .
If you can get the boards powered outside the case, a very effective method is to tap around with something non conductive. This will flush out poor connections if you have audio at all. If you have a multimeter you can test caps in situ with no power,but look for open or short the values may not not read correctly in a circuit. Be careful, they store up, if they discharge into your body, cross them off the schem as good.
Just a visual can go a long way, I don't know your skill level but any surgery after that is advanced , not hard but it's easy to mess things up. If you do choose to take it apart, get somewhere you won't be interrupted. Prolly my best advice.
Good luck, if you determine its too much, put it up for sale . There are people out there that can repair it, or as Red hat said, a pick n pull for their same model if it's cheap enough.