Call Search
     

New to Ham Radio?
My Profile

Community
Articles
Forums
News
Reviews
Friends Remembered
Strays
Survey Question

Operating
Contesting
DX Cluster Spots
Propagation

Resources
Calendar
Classifieds
Ham Exams
Ham Links
List Archives
News Articles
Product Reviews
QSL Managers

Site Info
eHam Help (FAQ)
Support the site
The eHam Team
Advertising Info
Vision Statement
About eHam.net

   Home   Help Search  
Pages: [1] 2 Next   Go Down
  Print  
Author Topic: IC-706MK2G Intermittently turning off then immediately turns back on  (Read 10897 times)
N4YNU
Member

Posts: 15




Ignore
« on: August 10, 2013, 08:24:49 AM »

I have been off the air for some time and a friend gave me a MK2G that he said had a issue :
When radio is on it will intermittently turn off and then come right back on
So I sent the radio to the ICOM Service Center in Nevada ...........(I did not test this before I sent it off because I trusted the person and their report regarding the problem)
They could not get the radio to present this problem so they sent it back
After receiving it I hooked it up and it had no issues , so me and the previous owner were stumped.
After using the radio to load up on different bands with ant tuner while fine tuning the antenna it started doing it after about a month , just randomly will power off for a split second and then back on to original frequency , outside of this the radio works and operates fine , it will even do this while transmitting , not only when idle.
AUTO Power off function is turned off in set up menu for GP
I have tightened all PCB mounting screws and made sure spring type grounds were mating with cover.
I have done some searching on the issue and it seems it may have to do with PA relay but those discussions were based on the relay sticking or not making on power up correctly , so I did not get a clear answer regarding this issue.
If I had to guess I would have to assume it could be worn ( barely making contact) relay contacts that are intermittently breaking and making do to wear of contacts or loss of flex of the relay spring , it could also possibly be what actually keys the relay failing possibly a switching transistor Huh

Anyone who could shed some light on this issue or has had the same issue and can share what the problem was would be greatly appreciated , THX

Guy
N4YNU
Logged
KE3WD
Member

Posts: 5694




Ignore
« Reply #1 on: August 10, 2013, 08:33:28 AM »

First suspect is loose connects in the power harness.  Check the molex type connector at rear as well as those inline fuse holders, usually can be done by simply wiggling them while the radio is on and observing what happens.  These can usually be retightened if necessary, needlenose, etc. 

Second suspect is internal to the radio, there is a known condition in some of them where some Sonybond glue rots the circuit trace along the edge of the power board, this is corrected by locating the brown stuff, mechanically scraping it off, cleaning up with alcohol and sometimes soldering a short jumper wire across the corroded pcb trace.  I don't think this is your particular problem, however, as I've yet to encounter one where the customer said it was intermittant at first, when this one happens, it shuts down and stays down.  So check those connnectors and fuse holders carefully. 


73
Logged
AD5X
Member

Posts: 1429




Ignore
« Reply #2 on: August 10, 2013, 01:43:30 PM »

Also - check the power cable in-line fuses and fuse holders.  Those fuse holders are real crappy (in my opinion), and can get loose on the fuses over time.  I snipped them out and replaced them with automotive blade fuse holders.

Phil - AD5X
Logged
KE3WD
Member

Posts: 5694




Ignore
« Reply #3 on: August 10, 2013, 01:48:01 PM »

ECHO TEST echo test

Hey, there really is an echo in here. 

Big room.



73
Logged
N4ATS
Member

Posts: 807




Ignore
« Reply #4 on: August 11, 2013, 04:44:46 AM »

The IC-706 has a typical OFF-ON-OFF symptom that can be repaired by popping the top cover and in looking in the very first section behind the head unit of the radio. You will see "3" flat ribbon cables that are bent 90 degrees and all 3 plug into the main board within abou an 1/8" from eachother. These ribbons are highly stressed and will break contact over time intermittently when current to the head unit increases. Remove the ribbons and remove some of the stress on the them then put them back on and this will most likely fix it. It works here on the ones that come into the shop.

« Last Edit: August 11, 2013, 04:47:10 AM by N4ATS » Logged
N4YNU
Member

Posts: 15




Ignore
« Reply #5 on: August 13, 2013, 05:12:49 PM »

I am so sorry everyone for not responding , life has been hectic and for some reason I have not been notified of the posts here and I am set to receive notifications and my email is right , so I re-clicked on my verification link , maybe that will resolve that issue ..............

Here is all I have done and deduced , which is not much but still working on it as I am taking the main board on the bottom loose now to look into a cold solder joint maybe Huh And I will be sure to check into those ribbons mentioned also , but here is where I am :

I opened up radio to check all the ground tabs to the covers and various screws and just barely tightened each in case maybe it was a ground issue , I checked the internal fuse and saw a dark spot in one end thought maybe that was the issue as I have seen it before , so replaced that .............did that on both boards/sides and replaced the covers and it did not do it again for almost 48 hrs ( I also did the fan mod while I was in which probably was not a god choice of timing regarding elimination ) .

So when I came home today , I went over fuses in the power cord , looked for possible bad spots from being bent for years and years ( basically broken wire in the insulation - I am sure you know what I am saying , just trying to be clear ) , I am using a brand new Astron VS70M and have check it real time as well but it is not the issue , checked power plug connections and actually closed the female lugs on each of the 4 conductors to make sure they were not the issue as well .

I might add I do not thin k it is a fuse issue or power cord issue as if I had that going on I do not think it would run full power reliably or without generating heat at the plug and or fuses and it is doing neither as I have been checking that also , everything I can think of .............

Ok ..............

So after doing the power cord thing I powered it up when I got home and it went nuts , it powered on about 4 times in succession before it would stay on , note : each time I can hear the relay drop and re-initiate , just like if I were to disconnect the power cord , then it randomly did it about 6 more times and stopped all together ..................... this is why I think it may be a cold solder joint , the PA relay or possibly what is keying the relay , maybe a bad switching transistor Huh?? No I do not have the service manual but have read some issues but most of those regarding the relay have been "power up or off" issues , not this "on and then off then back on" thing .

So I am pulling the back cover now and besides the ribbon issue mentioned I think I have covered all the other recommendations , so please let me know if what I have explained turns any lights on , I am going to keep this thread open on my browser so I can stay on top of it , again I am sorry but it has not notified me of one single reply Sad  , I will just leave it up and refresh throughout the day .

Guy

I will be sure to check the ribbon cables and that trace issue before I remove the board looking for a cold solder joint , TY everyone
« Last Edit: August 13, 2013, 05:19:06 PM by N4YNU » Logged
N4YNU
Member

Posts: 15




Ignore
« Reply #6 on: August 13, 2013, 06:16:23 PM »

The IC-706 has a typical OFF-ON-OFF symptom that can be repaired by popping the top cover and in looking in the very first section behind the head unit of the radio. You will see "3" flat ribbon cables that are bent 90 degrees and all 3 plug into the main board within abou an 1/8" from eachother. These ribbons are highly stressed and will break contact over time intermittently when current to the head unit increases. Remove the ribbons and remove some of the stress on the them then put them back on and this will most likely fix it. It works here on the ones that come into the shop.



I checked these ribbons and the front one was about out of the socket , and once I powered it up, it did it 3 times in a row and then stopped , so with the cover off I barely moved the ribbon ( smaller , all by itself ) and the front end died , so maybe something there Huh
I removed from socket and treated ribbon end with a very thin layer of deoxit and re-inserted , checking it now , so far so good but it is intermittent , so we shall see .

The only issue I had is a thin backing came off one of the group of three ribbons and I am pondering how to replace it as it most likely was used to increase width to maintain proper pressure in the socket , it came off when unplugged from the 2nd ribbon ( the center , #2 either way ) , I am thinking it should be replaced but what would I use for adhesive without making it too fat or damaging the ribbon material Huh
I was afraid to try super glue as I was pretty sure it would melt the plastic ribbon , maybe I should see if I can order a new ribbon Huh
Any Ideas Huh

Also it just did it again while I was typing this , it is not a slow off and on by the way , it is instantaneous off and back on , I could not reproduce this speed with the power button .

Guy
Logged
N4YNU
Member

Posts: 15




Ignore
« Reply #7 on: August 13, 2013, 06:31:17 PM »

First suspect is loose connects in the power harness.  Check the molex type connector at rear as well as those inline fuse holders, usually can be done by simply wiggling them while the radio is on and observing what happens.  These can usually be retightened if necessary, needlenose, etc. 

Second suspect is internal to the radio, there is a known condition in some of them where some Sonybond glue rots the circuit trace along the edge of the power board, this is corrected by locating the brown stuff, mechanically scraping it off, cleaning up with alcohol and sometimes soldering a short jumper wire across the corroded pcb trace.  I don't think this is your particular problem, however, as I've yet to encounter one where the customer said it was intermittant at first, when this one happens, it shuts down and stays down.  So check those connnectors and fuse holders carefully. 


73

Where exactly is this glue Huh
Maybe I should check this as well as I still have the issue after doing everything on this page , going to pull the power board tomorrow and check for bad joints maybe related to PA relay , I can here the relay dropping and re-keying each time , so I think I have covered the power issues , I think it has to be switching failure or a cold/cracked joint maybe Huh??
I am trying to catch a ghost , fan mod made no difference obviously hehehe , it is completely random , I com could not get it to do this at least that is what I was told , when I got it back it did not do it for about a week , so not sure if they did not catch it , or if it was like my cat that when he went to the doctor he acted fine lol , any other ideas would be helpful                           
Logged
WT0V
Member

Posts: 7




Ignore
« Reply #8 on: August 13, 2013, 08:30:57 PM »

My 706mk2g had the power cycling on/off than went completely dead.The cause was corrosion from rubber pads under the PLL board .I repaired the foil trace and radio has .worked since.Note this was a high serial #radio.
Logged
N4YNU
Member

Posts: 15




Ignore
« Reply #9 on: August 14, 2013, 10:27:13 AM »

My 706mk2g had the power cycling on/off than went completely dead.The cause was corrosion from rubber pads under the PLL board .I repaired the foil trace and radio has .worked since.Note this was a high serial #radio.

My serial # is 17527 , not sure what is a "high" serial # , could you provide me with a pic of the board or details so I can check that , it would be greatly appreciated , Thx

Guy
Logged
KE3WD
Member

Posts: 5694




Ignore
« Reply #10 on: August 14, 2013, 12:21:55 PM »

You should replace the ribbon cable that the backing came off.  That very likely could be your problem right there. 

Sometimes you can get a bit more life out of one of those laminated press-in ribbon cables that delaminate at the plug by coating the back area where the lamination is missing with a bit of the XYL's clear fingernail polish.  Make sure to let it dry thoroughly before attempting reinsertion. 

The Sonbond adhesive was only used in earlier manufactures, but rather than look for serial numbers and all that jazz I find it much faster and easier to simply visually examine the insides for the adhesive.  It is brown in color and hardens over time.  It crystallizes.  Sometimes manufacturers would swab it over an entire area of board and components, covering resistors and leads as well as using it for hold-downs for bits of black foam insulation or electrolytic caps.  When it ages and crystallizes, the stuff becomes conductive.  The cure is to simply and carefully scrape the brown junk away using something like the point of an xacto knife or a tiny screwdriver flat. 

Pay attention to the edge of boards for this stuff in the 706 that won't power up or suffers from shutdown probs.   They liked to pile it on at the edge of the pa board where the main power trace is.  Often there is a piece of black or gray foam there as well.  Scrape that brown stuff away carefully and examine the pcb traces underneath, sometimes they get eaten all the way through by the goo at the edge, where it can get under the silkscreen and eat away the copper trace.  Don't despair if the trace is gone or eaten, simple pcb board repair by scraping away the silkscreen down to bare copper, jump the area with bit of copper wire and solder. 


73
Logged
N4YNU
Member

Posts: 15




Ignore
« Reply #11 on: August 14, 2013, 01:14:43 PM »

You should replace the ribbon cable that the backing came off.  That very likely could be your problem right there.  

Sometimes you can get a bit more life out of one of those laminated press-in ribbon cables that delaminate at the plug by coating the back area where the lamination is missing with a bit of the XYL's clear fingernail polish.  Make sure to let it dry thoroughly before attempting reinsertion.  

The Sonbond adhesive was only used in earlier manufactures, but rather than look for serial numbers and all that jazz I find it much faster and easier to simply visually examine the insides for the adhesive.  It is brown in color and hardens over time.  It crystallizes.  Sometimes manufacturers would swab it over an entire area of board and components, covering resistors and leads as well as using it for hold-downs for bits of black foam insulation or electrolytic caps.  When it ages and crystallizes, the stuff becomes conductive.  The cure is to simply and carefully scrape the brown junk away using something like the point of an xacto knife or a tiny screwdriver flat.  

Pay attention to the edge of boards for this stuff in the 706 that won't power up or suffers from shutdown probs.   They liked to pile it on at the edge of the pa board where the main power trace is.  Often there is a piece of black or gray foam there as well.  Scrape that brown stuff away carefully and examine the pcb traces underneath, sometimes they get eaten all the way through by the goo at the edge, where it can get under the silkscreen and eat away the copper trace.  Don't despair if the trace is gone or eaten, simple pcb board repair by scraping away the silkscreen down to bare copper, jump the area with bit of copper wire and solder.  


73

I may order all the ribbons and replace , BUT , what I did is insert the piece that came off first then insert the ribbon on the front side of that piece , I just did that and have so far not had it "power on and off" , so it may be that without that extra piece it was not maintaining a solid connection which makes sense but this issue returns just when I think I have it solved so I am not going to celebrate just yet .

I did look for the brown stuff on the top of the PA Board and did not see any which is why I asked exactly where it might be in case I needed to look in a specific place or maybe remove the board to look on the bottom side.

It seems that the pink colored smaller ribbon on the side coming off that board may be an issue as well and the backing came off of that as well , so when I removed and replaced it may have slid up and caused the same issue ( this smaller ribbon to the right is one where when the radio was powered on I touched and the power toggled just like it has been doing) so I carefully inserted that first , then the ribbon .

I think I may as I said order all the ribbons feeding that top board (with exception of the one feeding the radio head which I removed , treated and re-inserted as well) just to be sure , will have to get part numbers for these 4 ribbons and order them , this way I can eliminate that as a issue all together.

So far after re-inserting that strip in the center ribbon of the group of 3 on the top board I have not had any issue (also reset the smaller pink ribbon on the right which had the same issue as of today)
, that may be why after removing and re-inserting without that little strip that the issue was much more active , so if this solves the issue then it most likely was the ribbons to begin with , I should have realized sooner the importance of that extra strip regarding the fact it was there to provide the proper pressure on the connections between the ribbon and socket .

So far so good , over a hour and no resets , time will tell.

Anyone having the Part #'s for those 4 ribbons :

Removing top cover - Frt board behind head :

3 white ribbons (sockets in a row 123) at rear of front board and 1 (single) smaller ribbon on the right (pink ribbon tape in my radio)
If someone could provide me with part numbers that would be a great help or maybe had a PDF Service Manual and I would gladly print it and find the part numbers myself , Thank All who have Helped me here , I really Appreciate your time and input.

It just reset again so problem is still lurking , very frustrating but will wait for some more input on possibly finding this ghost  Sad , maybe I need to check the other end of that pink ribbon since that created the issue before by touching it , will check the other ends of the white and pink ribbons and start another test time , so frustrating these intermittent issues are .


Guy


« Last Edit: August 14, 2013, 01:27:54 PM by N4YNU » Logged
N4YNU
Member

Posts: 15




Ignore
« Reply #12 on: August 14, 2013, 02:22:14 PM »

I just removed bottom rear board ( loaded with tuning coils and relays ) and checked the ends of the ribbons from top board , they looked seated well but in the interest of a dry connection , I removed , treated and re-inserted , I also did the same for the pink ribbon that led to the bottom front board , in another test session now to see if it "powers on and off" again, time will tell, powered back on at 1720hrs .

Guy
« Last Edit: August 14, 2013, 02:28:42 PM by N4YNU » Logged
WT0V
Member

Posts: 7




Ignore
« Reply #13 on: August 14, 2013, 06:50:57 PM »

Service manuals can be downloaded from the internet for free.The service manual will provide you with part numbers .My 706mk2g serial number is in the area of 1,507,000.I down loaded my copy from Rigpix.Do a search for Icom Ic-760mk2g rubber pads you will find pictures.73's de WT0V
Logged
N4YNU
Member

Posts: 15




Ignore
« Reply #14 on: August 14, 2013, 07:47:42 PM »

Service manuals can be downloaded from the internet for free.The service manual will provide you with part numbers .My 706mk2g serial number is in the area of 1,507,000.I down loaded my copy from Rigpix.Do a search for Icom Ic-760mk2g rubber pads you will find pictures.73's de WT0V

Thankyou for the Service Manual info , got it and downloaded for future use and found the ribbon cables , so will call and order , I would imagine they would have them , we will see , now that I have order #'s and such I will go and check out the rubber pad info you gave me as well , so far after removing , treating and re-installing the other ends of those ribbons , since 1720 hrs today it has not done it again , so hoping I caught the ghost , if it proves to continue then I guess it could be written off as a dry connection .............time will tell but I will order and replace the ribbons as they have been thru allot and I want to remove the possibility of a broken conductor in the ribbon possibly that may just be behaving now as it has been manipulated so much now .

 Thankyou Everyone for your comments/ideas , I will keep you posted Smiley

Guy

Guy
Logged
Pages: [1] 2 Next   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.11 | SMF © 2006-2009, Simple Machines LLC Valid XHTML 1.0! Valid CSS!