No RX or TX after changing frequency


N5LFE-Mark
 

Hello,
I have two ic7000's belonging to a friend that I am trying to evaluate / troubleshoot / fix. They both have the same odd problem. When first powered up, they seem to work properly. However, if after 20-30 seconds of operation you change memory channels or move the VFO frequency at all, then there is no longer any RF output and the receiver goes deaf, although there is still noise. I have not checked with a scope yet, but it seems like the DDS or TXCO stops producing a signal, although the frequency display looks and acts normally. Anyone have experience with this issue? Is it a common known failure? Are parts available? Thanks.


Paul Hansen
 

Very likely the logic unit. It’s part number 98414989 and I think it will cost you around $350 excluding shipping. It could be the DDS unit but my money is on the logic unit. The DDS unit is NLA.

 

Thank you,

 

Paul W. Hansen, W6XA

Amateur Radio Service

2134 Carthage Road

Tucker, GA 30084

(864) 222-3539 office

www.amateurradioservice.com

 

 

From: ic7000@groups.io [mailto:ic7000@groups.io] On Behalf Of N5LFE-Mark
Sent: April 24, 2020 13:23
To: ic7000@groups.io
Subject: [ic7000] No RX or TX after changing frequency

 

Hello,
I have two ic7000's belonging to a friend that I am trying to evaluate / troubleshoot / fix. They both have the same odd problem. When first powered up, they seem to work properly. However, if after 20-30 seconds of operation you change memory channels or move the VFO frequency at all, then there is no longer any RF output and the receiver goes deaf, although there is still noise. I have not checked with a scope yet, but it seems like the DDS or TXCO stops producing a signal, although the frequency display looks and acts normally. Anyone have experience with this issue? Is it a common known failure? Are parts available? Thanks.


N5LFE-Mark
 

Thank you Paul. Any risk to a DDS unit from a working radio to temporarily substitute it for test if the logic unit is actually failed? I know the ribbon cables are a bit fragile. I don't want to fail the working radio, given the DDS availability problem. Sounds like these two radios might become spare parts.  


Chuck Scott <cscott@...>
 

Mark:

Note that replacement of the logic unit requires a full alignment which may be difficult outside of an Icom shop. So the price of doing this is usually prohibitive.

Second, note that problems with the logic unit can often be simply issues with the connections to the board it plugs into (main?). In the case of my well used mobile IC-7000 it seems to be fine on my bench after cleaning the contacts, but not reliable in my truck anymore.

I really needed another HF/VHF/UHF radio on my bench. :-(

Chuck - N8DNX


On 4/24/2020 2:50 PM, Paul Hansen wrote:

Very likely the logic unit. It’s part number 98414989 and I think it will cost you around $350 excluding shipping. It could be the DDS unit but my money is on the logic unit. The DDS unit is NLA.

 

Thank you,

 

Paul W. Hansen, W6XA

Amateur Radio Service

2134 Carthage Road

Tucker, GA 30084

(864) 222-3539 office

www.amateurradioservice.com



Paul Hansen
 

No but it’s easier to move logic units.

 

Thank you,

 

Paul W. Hansen, W6XA

Amateur Radio Service

2134 Carthage Road

Tucker, GA 30084

(864) 222-3539 office

www.amateurradioservice.com

 

 

From: ic7000@groups.io [mailto:ic7000@groups.io] On Behalf Of N5LFE-Mark
Sent: April 24, 2020 15:09
To: ic7000@groups.io
Subject: Re: [ic7000] No RX or TX after changing frequency

 

Thank you Paul. Any risk to a DDS unit from a working radio to temporarily substitute it for test if the logic unit is actually failed? I know the ribbon cables are a bit fragile. I don't want to fail the working radio, given the DDS availability problem. Sounds like these two radios might become spare parts.  


N5LFE-Mark
 

Thanks Paul and Chuck. Didn't realize how easy the logic unit is to remove. I pulled the logic unit from one of the bad radios and put it in the test/good radio. It worked fine. So, the DDS is probably bad in both defective rigs. I may pull one and try it in the good rig to confirm.  I have a used ic7000 that someone gave me, but it works and I've not opened the case before. So, this is my first venture into one of these. The clock battery is bad in mine, so I may replace that when I have the time.


Paul Hansen
 

The DDS unit is easier to remove if you take the logic unit out first. It’s kind of in the way. I can’t stress enough how careful you have to be with those flat flex cables.

 

Thank you,

 

Paul W. Hansen, W6XA

Amateur Radio Service

2134 Carthage Road

Tucker, GA 30084

(864) 222-3539 office

www.amateurradioservice.com

 

 

From: ic7000@groups.io [mailto:ic7000@groups.io] On Behalf Of N5LFE-Mark
Sent: April 24, 2020 18:12
To: ic7000@groups.io
Subject: Re: [ic7000] No RX or TX after changing frequency

 

Thanks Paul and Chuck. Didn't realize how easy the logic unit is to remove. I pulled the logic unit from one of the bad radios and put it in the test/good radio. It worked fine. So, the DDS is probably bad in both defective rigs. I may pull one and try it in the good rig to confirm.  I have a used ic7000 that someone gave me, but it works and I've not opened the case before. So, this is my first venture into one of these. The clock battery is bad in mine, so I may replace that when I have the time.


N5LFE-Mark
 

Update... I put the DDS board from the defective rig into the "good/test" radio. It seems to work just fine, so the problem is apparently not in the DDS unit or the logic unit. This is good news, maybe. Not sure where to go from here. The service manual is not very descriptive regarding frequency selection and data flow. I am guessing something related to the main board. I will check the ribbon cables to the DDS as I swap them back to their original rigs. I know the problem is not in the front panel/control head, as those work as well with the good rig. 


Peter
 

Hi Mark,

I been a certain times not use my ic-7000 , last week when I try to turn it on ,  the ic-7000 response with click and click from the power relay and can not power on the ic-7000 , after I cleaning the contacts between the front display unit to the main unit , the click and not power on was get solved but have same phenomenon as you have had.
Not know if you have found the caused and get the problem solved now ?  If yes.  Can you please sharing me with your experience as my reference.  
 
Thank you ,

pp75724@Peter


 

Just for the heck of it try changing the ribbon cables. at the front of the board. The cables are not expensive and are sometimes problematic.
I have not had this particular problem, but have traced signals all over looking for other problems. They tend to crack if they are bent over and pushed on.


Peter
 

Hi Barron,

Thank you for your information , in actually , I have been replaces all these four (28 pin x2 and 30 pin x2 ) FFC ribbon cables with new one , but the problem still happen .  from the beginning when I press the power button the rig just response with click and click and can not power on ,  since my rig been suffered with the front panel with a short capacitor and caused a 4.7 ohm resister for 8V regulator get burnout in the main board , So, I had double check it and the capacitor and the 4.7 ohm resister all are ok , Therefore,  I have clean the contact pins between the main body and the front panel also replace all the four ribbon cables , but finally, the problem with no Rx after I either changing the frequency by turn the VFO or Microphone . 

Anyway , Thank you again ,  and I will keeping to dig the the root caused .


 

I assume that the start was the click - click problem that is usually a short in the control head taking out the 8 volt from the main board. 
After that was resolved I again assume that you had the 8 volt from the main to the panel and then the +5 and the +3.3 volt supplies alive and well.
It is possible that at that point you have another problem in the head. When the control head gets power the cpu sends a signal that it is alive and ready to the main cpu where the relay is not dropped out.
I suspect that a second problem was created when working in the head.
I believe the PWK signal makes a ground that pulls down the device that initiates the POWER ON SEQUENCE.
I would trace that signal to find out why the relay is no longer pulling in. PWK goes to the  IC1302 to initiate turning on.
The control head has no voltage on it until the relay pulls in.
The voltage present should be the voltage pulled down by the power switch. Check for that voltage on the switch at the transfer jack pin 2.
After the relay pulls in 8 volts at pin 1. 
I hope memory serves and it helps you fix your radio.
J.D.
KE4MD


On Mon, Dec 28, 2020 at 8:12 PM Peter via groups.io <pp-1-3-5-7-9=yahoo.com.tw@groups.io> wrote:
Hi Barron,

Thank you for your information , in actually , I have been replaces all these four (28 pin x2 and 30 pin x2 ) FFC ribbon cables with new one , but the problem still happen .  from the beginning when I press the power button the rig just response with click and click and can not power on ,  since my rig been suffered with the front panel with a short capacitor and caused a 4.7 ohm resister for 8V regulator get burnout in the main board , So, I had double check it and the capacitor and the 4.7 ohm resister all are ok , Therefore,  I have clean the contact pins between the main body and the front panel also replace all the four ribbon cables , but finally, the problem with no Rx after I either changing the frequency by turn the VFO or Microphone . 

Anyway , Thank you again ,  and I will keeping to dig the the root caused .



--
J.D. Barron


 

PWK goes to the lLOGIC unit via J651 to pin 135 on IC1302.


On Mon, Dec 28, 2020 at 9:35 PM Jeter Barron <jeter.d.barron@...> wrote:
I assume that the start was the click - click problem that is usually a short in the control head taking out the 8 volt from the main board. 
After that was resolved I again assume that you had the 8 volt from the main to the panel and then the +5 and the +3.3 volt supplies alive and well.
It is possible that at that point you have another problem in the head. When the control head gets power the cpu sends a signal that it is alive and ready to the main cpu where the relay is not dropped out.
I suspect that a second problem was created when working in the head.
I believe the PWK signal makes a ground that pulls down the device that initiates the POWER ON SEQUENCE.
I would trace that signal to find out why the relay is no longer pulling in. PWK goes to the  IC1302 to initiate turning on.
The control head has no voltage on it until the relay pulls in.
The voltage present should be the voltage pulled down by the power switch. Check for that voltage on the switch at the transfer jack pin 2.
After the relay pulls in 8 volts at pin 1. 
I hope memory serves and it helps you fix your radio.
J.D.
KE4MD


On Mon, Dec 28, 2020 at 8:12 PM Peter via groups.io <pp-1-3-5-7-9=yahoo.com.tw@groups.io> wrote:
Hi Barron,

Thank you for your information , in actually , I have been replaces all these four (28 pin x2 and 30 pin x2 ) FFC ribbon cables with new one , but the problem still happen .  from the beginning when I press the power button the rig just response with click and click and can not power on ,  since my rig been suffered with the front panel with a short capacitor and caused a 4.7 ohm resister for 8V regulator get burnout in the main board , So, I had double check it and the capacitor and the 4.7 ohm resister all are ok , Therefore,  I have clean the contact pins between the main body and the front panel also replace all the four ribbon cables , but finally, the problem with no Rx after I either changing the frequency by turn the VFO or Microphone . 

Anyway , Thank you again ,  and I will keeping to dig the the root caused .



--
J.D. Barron


--
J.D. Barron