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Old 29-10-2016, 09:41   #1
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Intermittant problem with Icom M802

I bought a used Icom M802 with AT140 tuner.

Installed it and did some tests, it appeared to work OK.

We have been traveling down the St.Lawrence, and costal till now and have not needed to use it.

Now that we are trying to use it for pactor email, there appears to be a problem:
After a few minutes of transmitting the power output drops to zero and it will not even tune. After a long time it starts to work again, and again will work for some time before stopping.

When it won't transmit, he only thing that restores it seems to be waiting: power on/off or turning off the breaker will not restore it.

When it is working there is no indication of a problem, it can transmit at full power, and I have made voice and pactor contacts without problem, but given enough use it will always lock up.

I have checked and improved my grounding, added my stainless lifelines and rudder post, even temporarily added a heavy cable out a port into seawater.

I have tested the antenna (insulated backstay). Also temporarily replaced it with a different length of #10AWG cable directly to the tuner out a port and hoisted with a halyard.

The only possible problems I have noticed:

the KEY voltage on the tuner control cable is 5V not 7.5V as stated in the manual, the 12v is ok (checked for min voltage during transmit).

I have not been able to get the remote control port to set the frequency.

Unfortunatly, All this testing and checking has made it too late to send the unit back to ICOM before we leave here.

Any ideas about this problem would be greatly appreciated.

Anybody know what would put the radio into a non transmitting state for an extended period of time?

Is the 5V KEY signal a problem, or just a different version from the manual?

Cheers,
JM.
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Old 29-10-2016, 10:09   #2
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Re: Intermittant problem with Icom M802

Not familiar with the 802 but have been involved in radio design, testing and repair for decades which leads me to suspect thermal cutoff. Most transistor final amp stages using heat sink cooling have a thermal switch which, when tripped, prevent damage and use until the heat sink cools.
As to why you have a heat dissipation problem, it could be low voltage, bad connection internally, poor installation preventing adequate ventilation or a bad final amp component.
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Old 29-10-2016, 11:23   #3
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Re: Intermittant problem with Icom M802

Could be that the cooling fan is not coming on.
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Old 29-10-2016, 11:46   #4
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Re: Intermittant problem with Icom M802

It is a familiar problem that the m802 suffers from internal corrosion at the flatcable connections. The m802 is not a real marine grade transmitter. It is a cheap constructed marine lookalike hamradio transmitter. It works great when new, as expected from Icom. The moist and salt air is drawn through the electronics without any protection, after ageing this cause corrosion. My comment is at the blackbox. The m802 is/was not approved in Europe due lack of IEC regulations (environmental tests tests ).
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Old 29-10-2016, 11:53   #5
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Re: Intermittant problem with Icom M802

You can try to carefully loosen the flat cables and replace them or clean them with cotton swap and spirit. Be extremely carefull otherwise the PCB connector could be damaged and not holding the flatcable.

This advise is for your own risk!
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Old 29-10-2016, 12:41   #6
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Re: Intermittant problem with Icom M802

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Originally Posted by donradcliffe View Post
Could be that the cooling fan is not coming on.
Absolutely, however, it should be very quiet so discerning the fan operation can be difficult if the radio is 'buried' in the bulkhead or cabinet.

Intermittent connections can be troublesome but would more likely fail when cold rather than hot so that quess seems pretty wild.
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Old 29-10-2016, 13:56   #7
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Re: Intermittant problem with Icom M802

The fan is coming on when transmitting.

The tranceiver chasis is never even warm to the touch. It is cool here in Halifax Nova Scotia Canada.

But, perhaps an internal component is overheating.


Cheers,
JM.
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Old 29-10-2016, 14:05   #8
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Re: Intermittant problem with Icom M802

Are you using full power when doing Pactor transmissions? This mode runs the final amp at full power essentially continuously, and perhaps is indeed overheating to the point of shutoff. In your place, I'd try running at one of the lower power settings. In most situations you don't need anywhere near 150 watts to make contacts with Winlink stations (or any others for t hat matter). I run my Icom 746 ham rig at between 25 and 50 watts routinely, both for Pactor and voice contacts...

Jim
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Old 29-10-2016, 14:18   #9
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Re: Intermittant problem with Icom M802

Quote:
Originally Posted by Jim Cate View Post
Are you using full power when doing Pactor transmissions? This mode runs the final amp at full power essentially continuously, and perhaps is indeed overheating to the point of shutoff. In your place, I'd try running at one of the lower power settings. In most situations you don't need anywhere near 150 watts to make contacts with Winlink stations (or any others for t hat matter). I run my Icom 746 ham rig at between 25 and 50 watts routinely, both for Pactor and voice contacts...

Jim
I have it set on hi power. Will try on low and see what happens.
I could imagine overheating with a hot ambient and prolonged transmissions.
However, this problem happens with very short messages, and the temperature where the radio is installed is about 16C. so, I think the radio should be able to handle it.

Cheers,
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Old 02-11-2016, 07:43   #10
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Re: Intermittant problem with Icom M802

I ran another test with the transceiver set to low power and it still failed fairly quickly.

Cheers,
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Old 02-11-2016, 15:22   #11
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Re: Intermittant problem with Icom M802

JM,
Sorry, I missed this thread earlier...

While I agree with the others that this sounds like a heat issue...but not necessarily in the PA...
Rather it sounds like either a heat issue in the microprocessor and/or in the control circuitry...
Quote:
Originally Posted by NahanniV View Post
The fan is coming on when transmitting.

The tranceiver chasis is never even warm to the touch. It is cool here in Halifax Nova Scotia Canada.

But, perhaps an internal component is overheating.


Cheers,
JM.
Easiest way to troubleshoot this, isn't too easy to do on-board...
But, if you've got a can of freeze spray (a common troubleshooting tool, available in any electronics shop), open up the M-802's Main Unit, and operate it as usual but with the cover off...
When it stops transmitting (or whatever other issue may come up), take the freeze spray and direct it on a few different locations...(the exact points, I will need to look at the service manual for a few, and I'm in the middle of something, at the moment)
Only spray in one location at a time...give it a few seconds, spray the same location again, and maybe a 3rd time....if no joy, then try another spot....and so on...

The microprocessor and its board connections....the control board and its connections....and any/all inter-board connections/connectors/wiring....
These would be my first points to direct you to...


Hopefully more later...

John
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Old 02-11-2016, 22:35   #12
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Re: Intermittant problem with Icom M802

JM, John is the Godsent angel and guru here and lots of good advice above also, but you may want to check artickles on this site regarding the M802, maybe something in there. They require you to register and you can only view one article for free per day, but I found their info very useful regarding my M800 and ic718.

mods.dk - Articles for Icom 'IC-M802'

Cheers,
Erik
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Old 05-11-2016, 07:37   #13
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Re: Intermittant problem with Icom M802

Quote:
Originally Posted by ka4wja View Post
JM,
Sorry, I missed this thread earlier...

While I agree with the others that this sounds like a heat issue...but not necessarily in the PA...
Rather it sounds like either a heat issue in the microprocessor and/or in the control circuitry...
Easiest way to troubleshoot this, isn't too easy to do on-board...
But, if you've got a can of freeze spray (a common troubleshooting tool, available in any electronics shop), open up the M-802's Main Unit, and operate it as usual but with the cover off...
When it stops transmitting (or whatever other issue may come up), take the freeze spray and direct it on a few different locations...(the exact points, I will need to look at the service manual for a few, and I'm in the middle of something, at the moment)
Only spray in one location at a time...give it a few seconds, spray the same location again, and maybe a 3rd time....if no joy, then try another spot....and so on...

The microprocessor and its board connections....the control board and its connections....and any/all inter-board connections/connectors/wiring....
These would be my first points to direct you to...


Hopefully more later...

John
Thanks,

There is a Winlink station operator near me who will take a look at my rig in his shop sometime this week.

Any specifics re. components that may be overheating, or connections that could cause the problem described would be great.

Perhaps I will take an IR thermometer to look for hot-spots.

What would you suggest for the contacts ? Cleaner ? Anti-Oxidant ?

73,
JM
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Old 05-11-2016, 19:10   #14
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Re: Intermittant problem with Icom M802

You could be having a problem with the tuner causing a suddenly high SWR. This causes the transmitter to fold back power and possibly overheat very quickly.

My suggestion to you is to NEVER run the rig at full power in a continuous keydown situation; such as any digital mode. There are very few transmitters that are designed for this. Use 50% or less power in any mode other than SSB. You're not gaining anything worth noting going from 50-150W on the other end. You would have to multiply your transmit by a power of 10 to even get 1 s-unit of increase. It's just not needed on digital modes.

If the rig is under warranty, send it in or exchange it for a new unit. If it has issues and is repaired they will likely also do any other fixes or software upgrades while it is in the shop. They will warranty the repair work as well. It will be repaired by someone who fixes a great number of that same unit every day and knows the easiest and neatest way to go about it.

If there is a known issue with moisture causing problems, after it is returned to you treat it with an electronics friendly hydrophobic spray and let it dry completely before reinstalling it. Icom may be able to help you with what product is best for your application that will not void warranties.

Check all your connections more than once. A poor power connection or ground can cause a lot of very strange behaviour from these radios. Even anderson power poles are not perfect and I recommend taking the connection loose and retightening it if possible. This allows you to check for corrosion and be sure that the connection is solid. You also want to check your antenna connections, tuner power connections, and put a meter inline to check the SWR when the tuner has stopped tuning. You can have full output on some rigs while still having a very bad mismatch between the tuner and the radio. Meter the cable if you have any doubts that it is of good quality.

There are products that will work to keep the voltage to the radio constant. There is never something for nothing, but if interested TGE has this unit.
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Old 07-11-2016, 15:03   #15
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Re: Intermittant problem with Icom M802

JM,
Oppss, sorry I forgot to come back here and answer you!

1) The answers are:
--- Look at the CPU (under the DSP board), towards the front of the main unit...and spray there...
--- Also look at the DSP board and its connections...and try spraying there as well..
--- Also, spray the inter-board connections...
--- And, you may also try on the PA itself...although doubtful it is the PA transistors themselves, it could be some other component there...

Use freeze spray on only one of these locations at a time...otherwise you may "fix" the problem temporarily, but not even know where/how...

Many times you can find not just a bad connection, but bad solder joints/connections....and sometimes you can find a component that is cracked, and/or is changing value when heated, but returns to normal when "freezed"...

Please do NOT adjust anything inside there!!
Unless you've got the equipment and expertize, there is nothing there that you can adjust that would do any good, and a LOT that would get screwed-up!!

If you find a connection issue....I prefer denatured alcohol, but de-ox-it spray works well too....if a surface-mount solder connection issue is found, please be careful (I haven't the eyesight or eye-hand coordination for them anymore) and perhaps the Winlink station guy is good at that??


2) While it is highly doubtful you have a VSWR issue causing this M-802 shut-down, as I'm sure you would've noticed this ("SWR" indicator) and certainly also not been an issue that "fixes itself upon cool down"....but, do have a look at the M-802's display when this happens, and let us know what it says...
The APC in the M-802 is pretty good, and won't allow you to overheat the PA, even it operating into a dead-short or open-circuit...so, no worries there....but...
But, there is always the possibility of a APC circuit failure...(so use the freeze spray there too...)


3) Also, JM, as you are aware the M-802 is rated at 150 watt output, 100% duty-cycle, in all modes, including FSK....and FSK/SITOR/PACTOR-I is a 100% duty cycle mode...
But, once initial contact is established (a few seconds of transmitting) with a PACTOR shore station (Winlink or Sailmal), a PACTOR-II or PACTOR-III connection is established automatically (or even PACTOR-IV, if on Sailmail and you are so equipped)....
And, JM, you are aware that PACTOR-II is a 50% duty-cycle mode, where your average output is approx. 50% of PEP....or about what a speech compressed / processed SSB Voice signal is...
And, a PACTOR-III signal's duty-cycle will vary form about 35% to 65%, depending on conditions / connection speeds....
So, under normal operating conditions (adequate airflow, room-temp air, etc.) when there is no malfunction in the M-802, there is no need to worry about the PA being over-heated when being used at its rated 150-watt output...

Also, as you are aware....as long as you have the M-802 wired correctly, there is no need for any "battery booster", as they M-802 (like all other part 80 type cert rigs) must operate / meet its designed specs, at full-output, over its entire voltage range...in this case 13.6vdc +/- 15%...(that's 11.5vdc thru 15.6vdc)
So, as long as you don't have an intermittent power connection, you're good to go...
BUT...

But, something you wrote earlier slipped past me....you wrote: "turning off the breaker will not restore it"....
And, I'm now thinking: "what breaker?"...
Standard practice calls for the radio to be powered directly from the hosue battery bank (or buss bar), and NOT thru a breaker panel / distribution panel, as these typically allow way to much voltage drop (as well as present significant opportunities for RFI)....
So, if you have the rig powered thru a breaker panel / distribution panel, you may have an intermittent connection issue there, that once it cools off, is good to go....but once it heats up is causing a low-voltage cut-out???
So, please wire the rig to the batteries or buss bar, using a larger gauge wire than what is supplied with the M-802, and test again....you may find the trouble in short order!!



3) If you still have no luck in tracking down this intermittent issue, a call to Icom service would be a good thing!!
The team that does their marine HF gear is pretty good!!
Yes, it's way out-of warranty, but Icom will repair it!!!
Give them its serial number, and have 'em check to see it its been in their shop before...

And, since you bought the rig used, we have no way of knowing what it may have been thru (lightning?, other repairs?, etc.), so please tell Icom this as well....that way they won't try to soak you with a big repair bill, if they feel you may be better off with a replacement radio (I highly doubt that, but just tell 'em it was bought used and you don't know the history....the serv guys in WA that work on the marine HF gear are good...)



I hope this helps...
Fair winds..

John
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