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Author Topic: Icom IC-2100H with no transmit audio  (Read 5644 times)
WA4ZYN
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Posts: 39




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« on: May 06, 2013, 06:06:48 PM »

I recently received an Icom IC-2100H in return for some work.  The rig looks perfect.  The only problem with it is that there is no transmit audio.  I have checked its receive, which is perfect, and its RF power output, which is at full level.  The friend who gave it to me said that he tried various microphones with it, with no success.  It has an HM-133V microphone.  Has anyone else had this problem?  Any successes, suggestions?

Thanks for your consideration.

73,
Francis WA4ZYN
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K5LXP
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« Reply #1 on: May 07, 2013, 06:01:14 AM »

The 2100 is a pretty easy radio to work on.  That's about your only option, as to pay someone bench time to look at it would exceed its value.

A few minutes with the schematic and an o-scope would find it in pretty short order I'd suspect.


Mark K5LXP
Albuquerque, NM
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N4ATS
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Posts: 799




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« Reply #2 on: May 07, 2013, 11:13:06 AM »

Download the service manual (it is free) , replace L-6. Common problem... (near the mic connector on the main board)
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WA4ZYN
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Posts: 39




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« Reply #3 on: May 07, 2013, 08:08:28 PM »

Thanks to both of you.  I have downloaded the service manual, and will get on to your ideas as soon as possible.  Thanks so much for the information.

73,
Francis WA4ZYN
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WA4ZYN
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Posts: 39




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« Reply #4 on: May 07, 2013, 08:40:31 PM »

Regarding L6--what exactly goes wrong with this inductor? 
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N4ATS
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Posts: 799




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« Reply #5 on: May 08, 2013, 03:58:28 AM »

Sometimes they go open. They are extremely sensitive. There are 6 or 8 others near L-6 , check them all , they should be a few ohms or less. If it is open , just short the pads to test the radio , If it works , let me know  and I will send you a few new ones on me , I have a reel full.  ( grassa@earthlink.net ) www.N4ATS.com

L-6 and the others are located on the logic board right smack behind the microphone connector. Look at the "Bottom View" (page 8-2) of the service manual . lower right corner
« Last Edit: May 08, 2013, 04:07:30 AM by N4ATS » Logged
WA4ZYN
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Posts: 39




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« Reply #6 on: May 08, 2013, 12:42:24 PM »

Thanks.  That's awfully nice of you to offer the inductors.  I will get to that ASAP.  I'm back-logged on projects right now--I think I left my bride a little "ham radio neglected" lately, and I've backed off from so many repair projects!  Live and learn. 

73.
Francis WA4ZYN
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WA4ZYN
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Posts: 39




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« Reply #7 on: May 13, 2013, 03:52:15 PM »

Hello again.  Well, I checked all the inductors at the microphone connector, L1-L8, and they all seem to be fine.  No opens at all.  What would you suggest for the next step?  I know that there is a voltage regulator for the +8 VDC for the electret element.  Is that a common failure?

Thanks so much.

73,
Francis

PS:  I actually do own a scope.  Just haven't learned how to use it yet.  Found it for a good price, though, so I'd have it for someday.
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N4ATS
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« Reply #8 on: May 14, 2013, 05:12:08 PM »

Next check the output frequency. It may appear to be putting out full power BUT is it on frequency?
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WA4ZYN
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Posts: 39




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« Reply #9 on: May 14, 2013, 06:44:09 PM »

hmmmmm.  interesting idea.  I'll give it a check.

tnx.
73,
francis
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N4ATS
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Posts: 799




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« Reply #10 on: May 18, 2013, 09:30:13 AM »

Just put both radios on Simplex and see if you can hear eachother clear.
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WA4ZYN
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Posts: 39




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« Reply #11 on: May 20, 2013, 07:49:32 PM »

hello again. I just wrote you a great reply, but it is somehow lost.  I will try again.  I tried your suggestion using my handheld.  With both the handheld and the 2100 on 146.52 with a dummy load, I found both were definitely on the same frequency, and that the 2100 had excellent receive audio, but again no transmit audio.  I tried a piece of ethernet cable with the mic, just in case the mic cable were bad, but that made no difference.  I now know I either have a bad microphone (though my friend said he tried several Icom mics to no avail), or something in the audio amp chain.  I tested at the microphone jack, and found the proper voltages there, so that's not it.  I guess I will now dust off my recently-acquired oscilloscope and study up on how to use it.  I also recently acquired free at the local hamfest an old heathkit signal generator and heathkit signal tracer.  I don't know yet if they work, but they could sure come in handy if they do.

73,
Francis  WA4ZYN
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K1CJS
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Posts: 5879




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« Reply #12 on: May 21, 2013, 05:11:45 AM »

Just a suggestion, but examine the RJ45 socket mounting closely if the mic connector is mounted on the circuit board in either the mic or the rig itself.  Sometimes the soldering to the circuit board isn't robust enough to stand the tension put on it by the compression of the socket wire.  Could be that the soldered connection is broken.  That was the case with a no transmit situation I had on a Radio Shack 2 mtr. rig.  The pin from the RJ45 had broken loose from the circuit board in the transceiver.

Good luck and 73!
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WA4ZYN
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Posts: 39




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« Reply #13 on: May 21, 2013, 05:58:01 PM »

Thanks.  Will check that out. 

73,
Francis
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