Icom M502A Problem

[OspreyVic]

I have an Icom M502A that is less than a year old that is having issues.

The radio has always received signals clear without any problem. The problem is on the transmission side. The problem is intermittent in that it works today, but may not work tomorrow. The radio has been in for service, but after 4 weeks, they said they could not find a problem. The best description I have is that I have a carrier but no modulation. Friends, bridge tenders, and towing companies have all said the same thing on many different days. They say they can hear the carrier when I key the mike, but they cannot hear me (no modulation).

The microphone is what the Icom repair center said when I first called them. Unfortunately, because I still have the problem, they said the microphone was fine. The mike that picks up the users transmitting voice is actually a small a small pin-hole in the mike. Icom thinks that a lot of people put their thumb over this pin hole. When my 502 was in for service, that small pinhole was pointed out to me. Since then I have been very careful where my fingers are on that mike.

I installed an ATO/ATC Fuse Block Systems and eliminated all in line fuses so I do not think fuses are part of the problem.

The problem is intermittent. Today the radio worked and my radio check was successful on two different channels. Wednesday, no one could hear me.

The GPS, Radar, Fish finder, etc have no problems.

I do have another electrical problem and have no idea if the two problems are tied together in any way, but just want to make sure you have all the information.

I also have a Lenco tactile switch with L.E.D. indicators and retractor, Part #123. The LED lights are working in my driveway, but last week while on the water, the LED lights stopped working, which has happened before. The Lenco folks think it might be a voltage issue.

Does anyone have any suggestions?

 

[Dave LeGear]

Vic I would...

• The next time the Xmit function goes dead, start shutting other electrical equipment and see if it clears up? I am thinking (pure theory now) along the lines of a "common ground noise" issue.
• I would also see if the mic cord is getting a short of some kind though I would think you get it to cut in and out while pulling on the cord if such was the case...
• Check / Change the light and accessory switch positions one at the time during the dead Xmit and see if the bilge pump is either running or cycling at the same time? Does not take much of a voltage drop to confuse anything that has a ECU or smart chip as you well know.
• Try switching the main ship service battery (long shot) from the A to the B battery and see if it clears up just make sure the engine is NOT running when you make the switch Maybe the A-B switch has a vague spot in it... I have had to swap out those switches in the past for strange gauge / display problems. Matter of fact, I had one switch in the A position that would kill everything but the engine (thankfully) going over certain waves.
• Give the radio the old technical tap "thump it" to see if one of the PCB boards inside the radio is getting hot and breaking down by chance
• Did you get shocked when you got on the boat? You may need to run a better or second ground lead for the VHF and the static discharge (it has been very dry of late) is creating a issue...

Those are always a pain to troubleshoot for sure!

 

[OspreyVic]

Thanks for the GREAT ideas Dave. Printing your list and placing it on the boat now.

Your fourth bullet has me a little confused. If you have the time, would you please look at the "Article" we wrote called "Additions & Modifications to our 2005 Triumph 210". We eliminated the standard battery switch, and the article describes and shows pictures of our changes. After looking at that section, maybe you could expand on that item for me.

Normally, I do not get shocked when I get on the boat. We went out yesterday, so this morning I was on and off the boat over a dozen times with cleaning the interior and testing the radio with my wife using our handheld. Neither my wife nor I were shocked yesterday or today. Last Saturday my son was zapped when he climbed into the boat while it was in the garage.

Again, many thanks for your help. I will let you know how the testing goes.

 

[Dave LeGear]

Yep Brother,
Forgot all about your battery system (my bad) and the 3 switches with its smart isolated circuits.., I would still look at the "back" of each switch, and make sure the wire connections are still all "tight" and make sure that each switch is not only in it's proper position, but that the switches do not have any slop in them that could allow a temp loss of power supply / drop. Now you may not be able to "feel" such by hand when moving them, but many switches have a nice locking (indent) click feel and even then, the actual switch can have an internal break down (wave hopping) that is not readily apparent as has happened to me with some of your standard "Perko" offerings in the past

In reading your article our terminology is a little different (but has the same use) and I consider all battery banks NOT used for trolling motors as "Ship Service" units (Has to do with doing a lot of push ups years ago for using the "wrong" terms ) since they can supply power to the ship (boat) for both the engine & the running of all console gear. I do though understand what you are trying to convey but being able to "mentally" trace out your system this late is a lost cause and I would really need to see it all again

Now some people have dedicated batteries for starting others for running batteries, yet I was thinking in the terms of the "Factory Rigging" which is 2 batteries for everything (minus the trolling motor) and you just run on either A or B (1 or 2) battery alone all day long.... Now I have never seen a real strong use for the "both" position unless both batteries are weak and you have a slow cranking issue and may need to barrow a few AMPS Even then, many times that just drops both batteries even lower and can make the problem even worse... But you can't divide zero you know and can always try both! It sure beats floating out to Sea on a dead engine and sometimes I think the simple act of switching back and forth fixes such NOT because the battery was really that low, but because the switch was acting "funky" (non-official technical term) and then the engine started when you landed on the "Both" position

So your system is pretty unique and has a lot of fail safe features for sure! But as the saying goes "The more plumbing more possibility for leaks" you have a lot of connections (potential points of failure) that I would pull a once over "just" to make sure that over time you have not developed a loose connection or ground, from banging over a few waves in the past

I am also wondering about power draw / spikes with the Radar & Sonar running and is it (they) on their own circuit and more even more, important grounds? Here again, the point being that the VHF also has some smart circuits installed on the PCB and a voltage drop (even for a nano second) could scramble things that "may" kill your ability to Xmit. A simple power cycle of the radio (all the way off and back on again) though "may" correct such an issue just remember, that many PCB's will hold current for a while... So make sure you allow them time to discharge (at least 60 seconds) before turning power back onto the VHF.

I would also start looking for common / combo related issues such as.... When I key up the Mic the Radar screen or Sonar screen blinks, and then nobody can hear me Not to say that the issue is "not" inside the VHF or its own PCB at all, but troubleshooting of this type can "sometimes" show related effects (though may be hard to find) if one just keeps their eyes open the "instant" it happens

Though not related other than the fact it was also 12VDC system, but a great story on digging for the "Real cause" for sure... About 13 or 14 years ago (from what I recall) I had a customer that owned either a Audi 90 or a Porsche 944 (can't remember which right now) that kept blowing a headlight for no (at first) logical cause... One of those real mind benders if you know what I mean

So after a few trips to the dealership my Assistant Manager came to get me go over the issue again. Now I kept telling him and the customer that we need to really "duplicate the condition" so I went down "my" asking of questions trying in vain to "nail down" the real cause... One of my standard T/S questions was "Were you alone or was somebody riding with you when such happens?" This goes along the lines of "Was the A/C on? Or were you making a turn and had the signal on" etc,etc,.... Trust me, I had long mental of list of questions pending the issue, with electrical problems being one of my longest list! Ha-Ha...

Well come to find that it happened WHEN and I could make it do myself (Hot Dog) his wife was ALSO in the car and... After going down that T/S path further of what "she" was doing COME-TO FIND-OUT that when you pulled down the R/S Visor and then opened up the cover for the vanity light to put on her lipstick, it blew out the one headlight from a shorting ground! What a gas that was to finally to find So we put in a new bulb (again) disconnected the wire to old visor until the new visor came in on special order and could get swapped out... Problem finally diagnosed and fixed

I say such to help you "boost" your SA /Situational Awareness (think that is spelled correct?) to look and see what else may (or may not) be happening at the same time when you loose the Xmit function on VHF

Enjoy and let me know your final fix and if needed, call me and we can crawl all over it together at your house...

 

[OspreyVic]

Thanks again Dave.

I will check again for loose connections again this weekend. I am more inclined to think that it is a power issue, but will test everything I can.

We will take the boat out again this coming week, see what happens, and report back.

To me this is also a learning experience. Let me try all that I can before asking for your personal intervention. I greatly appreciate the offer, but hate to ask when there are still things I can check out myself.

Again, thanks for all these GREAT suggestions.

 

[Genelie]

I am going to assume that you Icon is a radio correct?? If so, I had a similar problem. 2 things to check for is power, and ground. The 2nd is the connections on the radio Anttena. I found my attenna connections to be in poor shape. I went out and bought a gold connector, and resodered. Now she puts out nicely.

 

[OspreyVic]

Putershark

Your suggestions sent me in the right direction. Here is what we think solved the problem.

We were using the wrong size wire at two critical places. Our bad for doing a bad install job, so we have no one to blame but ourselves.

The wire going from the "House" Blue Sea Systems Mini Battery Switch to the Blue Sea Systems MAXI Fuse Block with a 40 Amp MAXI Fuse was only a 10 AWG Marine Grade Wire.

And, the wire going from the Blue Sea Systems MAXI Fuse Block to the Blue Sea Systems 12 position with ground ATO/ATC fuse block was only a 10 AWG Marine Grade Wire.

We replaced both of these wires with size 6 AWG Marine Grade Wire.

As you had suggested, we were starving the Icom M502A of power. Without the power it required, we could not transmit. Sure, we could turn off equipment if we wanted to use the radio, but that was not a good solution.

We have only tested this on one day, Friday June 9, 2006 while out trying to catch those elusive Tarpon. We were in Boca Grande Pass with around thirty other boats for over four hours. It was an outgoing tide and we had live crabs for bait, and while we had a few nibbles, we failed to catch a Tarpon. It was still great fun being with my son before he heads off to Florida State in Tallahassee. It was pure joy watching the Tarpon jump and play in large groups. The radio never failed us, so we believe the problem is solved.

Thanks for your guidance and suggestions. They sure pointed us in the right direction.

 

[Dave LeGear]

Glad to hear of the fix Vic! I know all to well how such problems can be a royal pain to address / correct and the "starving" the radio of power causing the issue sounds very logical indeed

Better luck next time on the Poon fishing Brother, and tell our future "Nole" there to study hard and enjoy himself in school! Just not so much that it starts to effect his grades

Maybe when life settles down to just a low roar for you, we can go hit some of the flats in your area in my boat

 

[OspreyVic]

Would really like to learn from you. There is just so much I am trying to fit into this thick scull of mine. I am going to really miss having my big guy around, but our loss is FSU's gain. Go Noles!!!