[ICOM] IC-756ProII Display, Receive dead

Thu Oct 23 07:11:13 EDT 2014

I had a display like that with my PROIII. Good when I used it the night 
before, dark in the AM. When I first turned it on in the AM is was dim 
and quickly went totally dark. I sent it to Tim Moes at Midwest 
Technical Svcs in Watertown SD and it was the PS to the back lighting of 
the display, several small FETS or diodes and rather reasonable to 
repair. Shipping up and back the major expense.
    Phil N0KE

Larry Young wrote:
> Jim; Sorry to hear of your ProII failure. From your description, It would appear that a problem has occurred in one of the radios supply voltages. As I no longer have either of my previous Pro series radios I do not have documentation for them. I remember there is a 5 amp fuse in the radio. I suggest you check it and find and measure the various DC supply voltage rails such as the +8 V, and +5 Volt  supply lines among others. Barring this, you may wish to utilize one of the excellent repair facilities such as W6XA in SC or Icom Michigan. The problem sounds simple to correct.
>
> Larry K4LXV
>
>
>
> On Wednesday, October 22, 2014 1:20 PM, Deric Affleck <deric.vy2da at bellaliant.net> wrote:
>  
>
>
> Hello Jim,
>
> Last January/2014 I had the display of my IC-756 Pro III go dark when I 
> turned it
> on one morning - it was fine when I had turned it off the previous night.
> Unlike your symptoms the receiver and transmitter worked fine - just no 
> display
> making it impossible to operate the radio properly. Fortunately my Pro III 
> was
> interfaced with my laptop so I could use Ham Radio Deluxe to manipulate the
> various functions. This occurred right in the middle of the FT5ZM DXpedition
> to Amsterdam Island so I was still able to contact them even without the 
> display.
> I scoured the internet looking for possible solutions and came across the 
> following
> links on You Tube concerning various problems with the older IC-756 
> including display
> failure and symptoms similiar to your Pro II so take a look at these videos 
> showing
> what is involved in locating and repairing similiar symptoms to yours of 
> course discounting
> the upgrading the display in the old Pro transceivier. Even though the 
> actual circuit board
> layout may differ between the Pro and the Pro II the circuit should be quite 
> similiar.
>
> http://www.youtube.com/watch?v=aMTMAZSEhOw
>
> http://www.youtube.com/watch?v=Q3POkGIA6rk
>
> In my Pro III the fault was a failed inductor in the power supply circuit 
> for the backlighting circuit
> for the display. The inductor opened shutting off the supply voltage for the 
> backlight.
> By watching the above video links I learned how to take remove the display 
> circuit board
> from the front panel, locate and replace the faulty inductor. I used a 
> slightly larger J.W. Miller
> inductor with better current rating that the Icom part so it won't act like 
> a fuse again. By the way,
> I contacted Icom USA who claimed they never encountered this problem before 
> (deny, deny, deny)
> and since the Pro III is an obsolete radio they don't stock the parts and 
> even though I gave them
> the Icom part # they said they didn't have it. It obviously is a common part 
> to other Icom radios but
> I was told they couldn't cross-reference it. Anyhow I purchased several new 
> inductors from an eBayer
> to have some spares which I probably will never need now. It took more time 
> to dis-assemble the radio
> than to replace the inductor, which by the way, was the only non-SMD part in 
> the backlight power supply
> and was a normal solder thru the board type. After re-assemblying my Pro III 
> I turned it on with bated
> breath - the display came to life and has been working normally for the past 
> 9 months - touch wood!
> Unfortunately, I think your problem is more involved than mine was so take a 
> look at the video links to
> give you an idea what could be the cause.
>
> Good luck & 73,
>
> Deric, VY2DA
> -------------------------------------------------------------------------------------------------------------------------------------
>   
>> Hey, Gang:
>>
>> The other night I put my trusty 'Pro II to bed in my usual way (powered it
>> down with the front panel power button and disconnected the antennas) 
>> after
>> using it on two nets with no issues. When I attempted to power it up the
>> following morning, the display was totally dark (no backlight, do
>> discernible characters), the S meter stood steady at around half-scale, 
>> and
>> there was no audio output. The S meter backlight and LED indicators were
>> lit, however. I tried a "hard reset" of the CPU, to no avail. I checked 
>> the
>> power supply voltage at the screw terminals inside the rig, and measured
>> 13.8 VDC. I visually inspected the chassis throughout, verified that all
>> connectors and ribbon cables were seated, etc., but turned up nothing
>> unusual.
>>
>> Before I pack the rig up for shipping to Icom Service, does anyone have 
>> any
>> suggestions as to what else I might check? I am a fairly capable (if I do
>> say so myself) bench tech, and have a good compliment of basic test gear.
>> What I'm really short on is TIME, so I'm hoping some of you here can offer
>> some guidance as to where best to look next.
>>
>> Thanks!
>>
>> W1IK
>>
>> William J. (Jim) Wickstrom, W1IK
>> Technical Director,
>> Utica/Shelby Emergency Communication Association (USECA)
>> w1ik at arrl.net
>> www.usecaarc.com
>>
>> ----
>> Your Moderator: Dick Flanagan K7VC: icom-owner at mailman.qth.net
>> Icom Users Net: Sundays, 1700Z, 14.316 MHz
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>>     
>
> ----
> Your Moderator: Dick Flanagan K7VC: icom-owner at mailman.qth.net
> Icom Users Net: Sundays, 1700Z, 14.316 MHz
> Icom FAQ: http://www.qsl.net/icom/
> To support QSL/QTH.net: http://www.qsl.net/donate.html
> ----
> Your Moderator: Dick Flanagan K7VC: icom-owner at mailman.qth.net
> Icom Users Net: Sundays, 1700Z, 14.316 MHz
> Icom FAQ: http://www.qsl.net/icom/
> To support QSL/QTH.net: http://www.qsl.net/donate.html
>
>