flooded icom ic 25

Discussion in 'Radio Circuits, Repair & Performance' started by ALPHA54, Apr 8, 2012.

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  1. ALPHA54

    ALPHA54 QRZ Member

    hi all masters tech:eek:. im a newbie here. can someone help me how or what particular parts of icom ic 25 which was flooded recently. after cleaning and drying power was still there, but

    1. frequency displayed 0.00
    2. tuning control knob click but no response
    3. s/rf indicator not lit up.
    4. s botton will respond but only the point will blink between one and two zero.

    im a student tech. i fixed some of my electronic equipment that were flooded.. but this unit ic 25 is my first hands-on. Can some one pin point what component might damaged.

    thank you in advance for your help.....God bless..:eek:
  2. W9GB

    W9GB Ham Member QRZ Page

    Standard Troubleshooting (which you should have been taught first week):

    1. START with the Service Manual and Schematic diagram for the IC-25 radio from the manufacturer (Icom)
    and you basic test equipment.

    2. THEN, start with power supply section of radio (where 12 VDC enters radio).
    Take voltage measurements with your DVM or VOM, comparong to factory spec measurements in Service Manual.

    3. ONCE these are proper (and failed components ordered and replaced), move on to receive side of this VHF transceiver.
    You can either take the signal trace approach or
    hook up a signal generator to appropriate point (disconnect PTT or protect your generator from accidental transmission into it)
    and go through the receiver stages.
    IF the mfg. provided specific alignment instructions, you may be able to use these as you check through the reciever stages.

    4. Now you have a working receiver, MOVE ON to the transmitter function.
    Attach a proper 50 ohm dummy load --- go through transmitter stages.
    At the end you shoudl have identified failed sections or parts and made necessary repairs.

    Troubleshooting is a methodlical and logical exercise that requires PATIENCE (People with ADD regard it as torture) ....
    Shotgun parts replacement is a Fools Journey (expensive) with a radio that has been underwater.

  3. ALPHA54

    ALPHA54 QRZ Member

    thanks you very much sir for your quick reply. i will download first the manual then fix my power supply then strat to troubleshoot. thank a lot..:eek:
  4. KB4QAA

    KB4QAA XML Subscriber QRZ Page

    With modern electronics operating at low voltages the most likely problem is shorting of components due to contaminants from the dunking and or minerals in the rinsing water.

    This is essentially a salvage situation. Typical method

    -Flush the device with copious amounts of water (distilled if possible)
    -Disassemble the radio so that you can access all components.
    -Use soft brushes like toothbrush or nail brush, and running water, clean around all components
    -Do final rinse with distilled water
    -Dry components in an oven at MAXIMUM 120F-130F (per military standards) for as long as it takes to be thoroughly warmed and dried. Perhaps an hour.

    At this point you have two problems to fight. Corrosion and repair. Corrosion will be a continuing problem with any electronics that have been dunked throughout it's life.

    -A cleaning with standard electronics spray cleaner (NO LUBE) would be a good step.
    -I have had success next with a good saturation with Caig DeOx-It and letting it drain and dry out over a couple days.
    -Finally, attempt repairs. There are no secrets, and no guarantee of any success. You may end up throwing the device away.

    Good luck! Bill
  5. WA9SVD

    WA9SVD Ham Member QRZ Page

    I think Gordo (Gordon West) wrote an article about this a few years ago. The first question is what is meant by "flooded.?" I'll make the (dangerous, I know) assumption you mean complete immersion in water; but was it salt water or fresh water?

    As outlandish as it may seem, the best next step (after removing the battery) would be to keep it submerged in water until you can actually salvage the unit. (The premise being that you can't do any further damage...)
    The next step would be several rinses (YES, total submersion for a minute or two) in tap water, especially if salt water was the original culprit. That should remove most of the salts and corrosive materials. the next step would be a couple or rinses (yes, again, total immersion) in distilled or deionized water (head out to Safeway, Vons, Ralphs, Kroger, etc.) to remove any traces of minerals from the tap water.
    Only then begin to dry the unit out, preferably in the sun, for several days. (But protect any LCD or similar display from direct sunlight.)

    When you are absolutely sure all traces of moisture are gone, then try to resurrect the unit; if it has any response at all, do a total processor reset, and see if it will work. if it does, you are back in operation; if not, you are just out a $or two for the distilled water, and some time. (IMHO, worth the effort.) The important thing is to keep the unit in water until you can reach fresh water; if salt water is allowed to dry on components, permanent damage and corrosion can occur.
  6. KH2G

    KH2G Ham Member QRZ Page

    If it was a salt water dunk - toss the memory battery also. Salt water tends to destroy batteries very quickly.
    Dick KH2G
  7. WA9SVD

    WA9SVD Ham Member QRZ Page

    Don't "toss" the battery. Replace it (ASAP) with the same type if at all possible. Salt water MAY kill it outright, but keep it until there's a tile to double (triple?) check the proper polarity. If the radio was truly dunked into salt water,the battery will probably toast, unless the radio was immediately immersed in clean, fresh water. I'd recommend the fresh water submersion (And rinse with fresh water) as soon as possible, if that is possible. Even a few hours submersed in fresh water would be preferable to a "quick dry" of any electronic device subjected to salt water exposure.

    Remember, our goal here is the eventual survival and "resurrection" of the radio itself (hardware) not the software (PROGRAMMING,) If all you value is the programming, that should have been programmed and documented in the past.

    SORRY if that's blunt and offensive. IF you have to use your H-T in a true emergency situation, and some well known repeaters are inoperable, WILL you know how to access emergency simplex and alternate repeater operations, which may require non-standard simplex frequencies, repeaters on previously unrecognized frequencies in your area?
    Last edited: Jun 6, 2012
  8. N7LRY

    N7LRY Ham Member QRZ Page

    If you have access to the equipment, after flushing with distilled water and or meticulously cleaning with 99.9+% isopropyl alcohol, place the unit in a vacuum chamber/bell jar. This will vaporize any moisture from even the smallest nooks and crannies. I used this technique on an old NIKON F2 that was dropped in the colorado river many years ago very successfully.

    Vacuum chambers are easy to build if you don't have access to one.

    Get a vacuum pump, the kind used for and in AC systems will work well. Ensure that the pumps inlet is well filtered and if required lubricated. Construct an air tight box with walls that can handle ~45psi. It is always best to engineer on the safe side. Connect the vacuum pump to the chamber and if possible have a gauge that can measure the vacuum you are pulling. Anything in the neighborhood of high 20s to 30 inches of mercury should be adequate.


    David Finell, N7LRY
  9. AF6LJ

    AF6LJ Premium Subscriber QRZ Page

    I wouldn't do that for the simple reason most all consumer grade electrolydic caps won't stand up to that much negative pressure.
  10. KB4QAA

    KB4QAA XML Subscriber QRZ Page

    Warming in an oven at 120F is simpler and within specs for most components.
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