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 Post subject: Embarking on a recap of some Icom radios. Looking for tips.
PostPosted: Jul Fri 12, 2019 2:04 am 
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Hi..

I am comfortable recapping 30's radios with lots of room and using a 200+ watt soldering gun... I know from transistor radio work, that is not healthy for circuitboards..

I am planning on recapping two Icon receivers (R71A and an R7000).

There are about 100+ small electrolytics in one of these radios, and the boards are rather delicate.. I am assuming I need to use a pencil iron, and perhaps a solder sucker? I need to be careful about static charges.

I am looking for any words of wisdom from anyone who has done this kind of work on this sort of radio...

Thanks,

George

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 Post subject: Re: Embarking on a recap of some Icom radios. Looking for ti
PostPosted: Jul Fri 12, 2019 2:57 am 
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Other "niceties":

- Grounded anti-static mat + grounding wrist strap

- Lighted hands-free magnifier

- Copper braid (to wick up melted solder)

- Flux wash

- Skilled PC repair operator

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 Post subject: Re: Embarking on a recap of some Icom radios. Looking for ti
PostPosted: Jul Fri 12, 2019 3:24 am 
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I'd practice on some less-valuable PC boards before tackling those. Recap a few transistor radios or late-era tube sets with PCBs to get some practice and learn how to avoid overheating the trace and lifting the foil from the board. Yes to the solder sucker, and the braid. Sometimes you need both.

If you can reach the leads from above, it's easier to cut the component loose first and then desolder the remaining part of the lead.

If the boards are double-sided or multi-layer, you'll need to be extra careful to avoid pulling out the plated-through holes. Apply heat when you are pulling the lead, unless you are sure there isn't any solder holding it to the plated-through hole.

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 Post subject: Re: Embarking on a recap of some Icom radios. Looking for ti
PostPosted: Jul Fri 12, 2019 3:53 am 
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Surely you don't need all new caps? Well maybe you do. :x
Another way is to leave a short stub in the board, hook and solder the new lead to that stub.

To remove a chip with multiple legs, heat and suck solder from each leg several times, then reheating the legs, raise the board with your other hand, and slap it down against the edge of the bench. The chip lands in a box on the floor. 8)

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 Post subject: Re: Embarking on a recap of some Icom radios. Looking for ti
PostPosted: Jul Fri 12, 2019 4:09 am 
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The schematic and layout diagrams in the service manual caused me to think twice before opening up that chassis.

I've been inside my Icom R71R a few times to do a minor mod, to replace memory board, and replace the meter lamp. As far as the circuit board goes, I installed one 1/4W resistor to improve AM filter; that was enough for me. I hope I never need to open the Icom again. This is for "advanced."

I don't think this type of radio needs complete "recap."


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 Post subject: Re: Embarking on a recap of some Icom radios. Looking for ti
PostPosted: Jul Fri 12, 2019 4:45 am 
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IC-R7000 recapping notes and caveats, + pdf strikeout list.
http://home.exetel.com.au/frolektrics/i ... rhaul.html

:) Greg.
oh... switch off all telephones, or work the graveyard shift. lol


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 Post subject: Re: Embarking on a recap of some Icom radios. Looking for ti
PostPosted: Jul Fri 12, 2019 1:26 pm 
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You might also find the archives of the ICOM R71A and ICOM R7000 Yahoo groups helpful.

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 Post subject: Re: Embarking on a recap of some Icom radios. Looking for ti
PostPosted: Jul Fri 12, 2019 1:29 pm 
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Use good 105 c caps when you do it. I have a R71A sitting here, hasn't been turned on in over 20 years. Also a JRC 525 and 535d same fate.


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 Post subject: Re: Embarking on a recap of some Icom radios. Looking for ti
PostPosted: Jul Fri 12, 2019 1:36 pm 
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I am also perplexed. What issue makes it seem that these relatively modern radios need recapped, to begin with? Some issue specific to those radios? That seems like a great deal of work for just "refreshing" the caps. I have a few ham radios, vintage 70s thru recent, and have not had an issue with those kind of caps so far. They were built with good quality Japanese made caps and do not seem to have the issues that cheap consumer goods with Chinese caps have. In the cases of people that I know have changed some, they replaced any specific bad parts, no shotgunning involved. Not to be confused with el-cheapo imported transistor consumer sets from the 60s or 70s. I have a KDK Japanese transceiver from the 70s or 80s that was a brand that some claimed had cap issues but mine plays on merrily as-is.

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 Post subject: Re: Embarking on a recap of some Icom radios. Looking for ti
PostPosted: Jul Fri 12, 2019 1:52 pm 
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Location: 18424 PA
R71a could be 35 years old now. If it was sitting and not being used, I would recap the entire radio. Scopes of higher quality parts from that era are due for a total recap also. I have Japanese caps from that era which though they look like high quality, are bad and leaky. I have powered on older equipment to check it's function, was fine. 2 weeks later, turned on again then functions and voltages were way off, due to caps failing.

Even if the radio has a specific problem and a 1 cap change fixes it, chances are more will be failing soon. Repair it right the first time. I'm sure there are particular failure problems with these, they made many. Memory and operating system failure due to lithium battery fails are well known and documented.


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 Post subject: Re: Embarking on a recap of some Icom radios. Looking for ti
PostPosted: Jul Fri 12, 2019 3:04 pm 
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My thanks to all for their thoughts and suggestions.

Also the link provided by Greg (egg) to the Australian article by someone who has recapped an R7000 provided both good information as well as a bit of confidence :) . It turns out that I also obtained my recap kits from VE3PVS (same as the author of that article).

I understand the different opinions regarding the shotgun recap, but I feel that if I do this, I only want to do it once. Also, the effort to properly diagnose the offending cap could be somewhat difficult. I also would not want a bad cap to possibly take out any other components.

I welcome any further suggestions. I will practice on a few of my transistors first... and I think I need to get the proper heat controlled soldering and desoldering equipment.

George

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- George Kaczowka - (K and Mumble a bit)
- http://www.oldradios.com (george@)


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 Post subject: Re: Embarking on a recap of some Icom radios. Looking for ti
PostPosted: Jul Fri 12, 2019 4:17 pm 
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Location: Mountains of Mourne. Ireland.
If the traces begin to lift, your iron is not hot enough - you want to get in-and-out quickly.

I use an Edsyn DS017 SOLDAPULLT (solder sucker). ~$20.00
Image

and... Fresh solder wick (braid).
An old fashioned hat pin or a dental pick is great for clearing holes. Never drill holes. lol


At times adding a small amount of fresh solder to a joint before desoldering often helps.
If your component is connected to the chassis, it will dissipate the heat faster than you can apply it - in this instance, use your widest (clean) tip, or a solder gun.

With (rosin-cored) fresh solder, you are also adding new flux.


Before and after...
I clean (and dry) with IPA (isopropyl alcohol) using a small acid brush or an old toothbrush. I use 70% (strength) isopropyl alcohol... mixed 50/50 with regular nail varnish remover (acetone), it leaves no residue.
In a past life I have used Zippo lighter fluid (naphtha) or denatured alcohol in a pinch.

Stronger % IPA is available (less water, dries quicker) - ask the Pharmacist.


More applicable to modern-day devices...
Adding lead solder to a lead-free soldered joint speeds up the removal process. It lowers the melting point.

Never use a pencil to mark a circuit-board, it can cause all sorts of trouble between traces. The small sharp pointed Sharpie is OK. lol
Safety Glasses→ viewtopic.php?p=3043731#p3043731
:) Greg.

oh... maybe mark all the tops of the existing capacitors (to be removed) with (white) correction fluid.

Watch out for solder blobs in the chassis, and never work when tired. It's really easy to install an electrolytic capacitor backwards.


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 Post subject: Re: Embarking on a recap of some Icom radios. Looking for ti
PostPosted: Jul Fri 12, 2019 4:18 pm 
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Buckle up and take a ride with Dave.
viewtopic.php?p=3030032#p3030032

Greg.


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 Post subject: Re: Embarking on a recap of some Icom radios. Looking for ti
PostPosted: Jul Fri 12, 2019 10:07 pm 
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My R7000 started fading out the display after it had been on for a few minutes - a bit of research found this is a common fault. More browsing said change all those caps on the DC-DC converter (the display converter, not the power supply converter) which I did - and no change! I reflowed all the solder joints on the display but again - no change.

I just happened to be watching in the dark one evening while it faded and noticed that the heater wire was fading too. If you look at that flexible PC that goes from the converter to the display you'll notice that they've doubled the solder pins and made the PC trace thicker but it's still not a very big cross-section of conductor. I added a wire from the transformer pins directly to the display pins both sides and it's never faded out since! Make sure that you don't cross the wires and put a dead short on the transformer! Your meter won't tell you much as it's all such low resistances.

Another mod - I started to notice a lot of distortion initially on WFM but crept into NFM too. Another bit of browsing found a mod to cure this. IC6A on the IF unit up at the very top right on the schematic - you'll notice that the positive input has a few components tied to to it but if you give a good look there is no DC path to ground. Now if C135 is slightly leaky or the atmosphere is even a little moist then it might work alright but my house is extremely dry, often below 25%RH, which may have brought on the fault. Solution - I added a 100k resistor across C135 and all is now good - pretty tight in there so be careful!

While you're in there - change the memory battery!

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 Post subject: Re: Embarking on a recap of some Icom radios. Looking for ti
PostPosted: Jul Sat 13, 2019 1:33 pm 
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Location: Long Island
They are your radios and you can do with them as you see fit, but I think the idea of replacing every capacitor in sets like these is internet lunacy. It should not be necessary in the first place, and it will likely do more harm than good.

Yes the caps will be suffering from deforming if the radio has been sitting for more than a couple of years without being powered up. But there is a very simple answer for that, just plug it in and if it powers up and functions at all, let it run for 2-3 days. The electrolytic caps should gracefully reform and after a few days be as good as new.

I recently took a Radio Shack DX400 out of storage and it refused to even power up initially. While I was taking the back off it started to play but was an absolute wreck with low volume, distortion, and little sensitivity. So I left it playing as well as it could on top of my washing machine overnight and next morning it was much better. I gave it another 24 hours of on-time to finish reforming and now it works prfectly and shows no signs of ever going back to its old habits. Of course if a relatively new radio that was in long term storage still has problems after running a few days, something more is wrong. In that case I'd troubleshoot it to the faulty component(s) and just replace what has to be replaced. Less chance of disturbing things that did not need to be disturbed, breaking PC board foils, or making mistakes like putting the new caps in backwards.

One thing to understand is that those Japanese capacitors from the 1980s were about as good as it ever got for modern electrolytics. Ultra low ESR, low noise capacitors for analog applications are lost art today. Even if you buy the best name brands and study every spec sheet, you may not be able to even match, let alone exceed the performance of the capacitors already in the radio.

NB: I am well aware of the "capacitor plague" in the early 2000's that resulted from some industrial espionage that misfired, as well as the SMD electrolytic cleaning solvent disaster that followed on its heels. Tons of equipment made in that era failed within a year or two due to faulty or damaged capacitors and what little was fixed, had to have all electrolytics replaced. But those were special cases and those experiences do not translate to all electronic equipment.

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