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Old 10-10-2013, 10:45 PM
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Default Does my maxtrac have a bad Crystal?

One day I turned on the 2M Maxtrac to do some simplex, Powerd up, BEEP, seems fine, Transmit, Herd fine over the air. NO RX AUDIO!

It knows when theres a signal there, will know when theres a signal even if its real weak. When there is a transmitting station on the frequency, Busy light flashes, I hear a click when the squelch opens but no audio at all after that.

Is this what would be a simple Crystal Replacment, an adjustment, or time for a new RF Board?

ive done my searching and ofcourse it sounds to be the 44.645 crystal. But Ive had the issue in the past where it does this but the audio instantly begins to fade in. ???


I would just replace it and see if it works but im unsure if its the issue, have no spare RF Boards and will appreciate any input before I go and order a crystal ...

Last edited by centuryvrproductions; 10-10-2013 at 10:48 PM.. Reason: clarifying
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Old 10-11-2013, 7:26 AM
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Just a guess, but be sure that radio isn't programmed for an Rx PL/DPL different from the one that the radios you're trying to listen to send.
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Old 10-11-2013, 10:43 AM
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If the 2nd LO crystal was bad you would not get a received signal indication (busy light). Since the radio responds (the pop in the speaker is the audio PA being enabled) I'd say the RF is working just fine and the problem is in the audio chain. If you had some kind of audio tracer, I'd be looking for detected audio. That would narrow things down considerably.
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Old 10-11-2013, 3:56 PM
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Check for audio, press and hold the Mon button, squelch should open and get noise in the speaker.

Also check at the mic jack on the headset pin for RX audio.
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Old 10-16-2013, 8:57 PM
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When I press and hold the Mon to open the squelch, I hear the button press Tone come out of the speaker, the Bsy light flashes as it is recieveing, but no audio at all comes through.

just a click when the squelch opens thats it.
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Old 10-17-2013, 3:34 PM
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Did you HOLD the MON button......... takes a few seconds for the squelch to un mute the audio.

The BUSY indication IS a good thing, says the receiver is working.

Last edited by cmdrwill; 10-17-2013 at 3:36 PM..
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Old 10-17-2013, 7:21 PM
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Quote:
Originally Posted by centuryvrproductions View Post
When I press and hold the Mon to open the squelch, I hear the button press Tone come out of the speaker, the Bsy light flashes as it is recieveing, but no audio at all comes through.

just a click when the squelch opens thats it.
When you power up the radio or press a button and hear a strong beep as normal, this indicates the audio PA amp is OK. By pressing and holding the monitor button you see a flashing "busy" light but no open squelch audio out the speaker.

OK, the audio starts at the detector chip on the RF board. This is raw detected audio, unsquelched and unfiltered. It is then passed over to the logic board where the squelch gate lives and the filters are that shape the audio. Not much on the logic board to oops on. If there is a problem there it would be at the component level and you would need a schematic and test equipment to troubleshoot.

I'd say you are missing the detected audio or the squelch indicator from the RF board to the logic board. This is a common problem with this era radio, a bad connection between the two boards. Easy fix though if this is the problem. Remove several torx head screws from the RF board and lift it out. Use a pencil eraser and some contact cleaner to scrub the pin connectors that go between the two boards.

This usually fixes most problems....
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Old 12-29-2015, 10:25 AM
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Default Here is the correct answer

Quote:
Originally Posted by centuryvrproductions View Post
One day I turned on the 2M Maxtrac to do some simplex, Powerd up, BEEP, seems fine, Transmit, Herd fine over the air. NO RX AUDIO!

It knows when theres a signal there, will know when theres a signal even if its real weak. When there is a transmitting station on the frequency, Busy light flashes, I hear a click when the squelch opens but no audio at all after that.

Is this what would be a simple Crystal Replacment, an adjustment, or time for a new RF Board?

ive done my searching and ofcourse it sounds to be the 44.645 crystal. But Ive had the issue in the past where it does this but the audio instantly begins to fade in. ???


I would just replace it and see if it works but im unsure if its the issue, have no spare RF Boards and will appreciate any input before I go and order a crystal ...
The motorola m100 radius maxtracs were known to have this issue.

This is why maxtrac upgraded since.

The earlier Motorola mobile radio products mostly used push-pull audio power amplifiers and audio output transformers, and drove the speakers as a hot wire to ground.
Many radios have no because
They go bad because they used to make their radios with speakers that ran off push and pull load.
Rather than direct ground and load
They used a capasitor like speaker magnet that was powered by another capasitor.

You can replace the speaker or
Replace the main capasitor

Better to salvage the radio....

Dont buy motorola m100 radios
They are not reliable version of maxtrac
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Old 12-29-2015, 10:26 AM
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Sell it on ebay and say no further testing done and take money and buy newer maxtrac
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Old 01-18-2016, 2:33 PM
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Quote:
Originally Posted by centuryvrproductions View Post
One day I turned on the 2M Maxtrac to do some simplex, Powerd up, BEEP, seems fine, Transmit, Herd fine over the air. NO RX AUDIO!

It knows when theres a signal there, will know when theres a signal even if its real weak. When there is a transmitting station on the frequency, Busy light flashes, I hear a click when the squelch opens but no audio at all after that.

Is this what would be a simple Crystal Replacment, an adjustment, or time for a new RF Board?

ive done my searching and ofcourse it sounds to be the 44.645 crystal. But Ive had the issue in the past where it does this but the audio instantly begins to fade in. ???


I would just replace it and see if it works but im unsure if its the issue, have no spare RF Boards and will appreciate any input before I go and order a crystal ...
.................................................. ...........
RE-
Powered up, BEEP, seems fine, Transmits, Herd fine over the air. NO RX AUDIO!

-Well you may just have a issue everyone else is having!
This is a very Very Common Issue with Motorola M100 or Maxtrac Radios.

I own a Maxtrac with the same exact issue.
Mine Defective M100 Maxtrac Powers on... Makes Beeps, Transmits fine just No RX Audio !
The reason for this is because The Huge Blue Capacitor inside the Radio is bad, or Blown.

I have done many research on this problem, even talked to techs who fixed this.
To Be Honest with you....

This is a very well known issue with the M100 Maxtracs and is why they updated to the newer model
Maxtracs.

This is Fixable if you have a capacitor and can do some soldering.
Really its not worth fixing, The radios only 2 channels and a dime of a dozen!

But yea,... The Power on, Transmits but no RX is Deff a blown Blue Capasitor inside radio!
I did much reseach!
Good luck~!
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Old 01-18-2016, 2:35 PM
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Quote:
Originally Posted by cmdrwill View Post
Check for audio, press and hold the Mon button, squelch should open and get noise in the speaker.

Also check at the mic jack on the headset pin for RX audio.

---------------

I know this is off topic but, How do i start a thread or post question on radio reference?

Thanks... Seen that you are online, Figured i ask
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Old 01-18-2016, 2:36 PM
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If the capacitor was bad in the audio output stage you would NOT hear the "beep" on power on.
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Old 01-18-2016, 2:38 PM
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To start a new thread posting go to New Posts at the top of the forum page.
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Old 01-18-2016, 2:54 PM
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Quote:
Originally Posted by cmdrwill View Post
If the capacitor was bad in the audio output stage you would NOT hear the "beep" on power on.
Well, My radio Didnt have RX Audio but it had beep...
The beep worked but it was so Low it was almost concidered to be defective!

Let me correct myself...

The beep did and didnt work.

It was hearable if.... You put your ear to The speaker you would hear the Beep and Open Squelch so Low
it was considered to be No RX Audio!

The Capacitor was bad but not blown... Blown it would of had No Way to Push and Pull the Load to the
Speaker.

I did replace the capacitor and My RX Audio came back.

Also if you look at the Terminals to the radios back Pin layout it traces to the Blue Capasitor.

The Blue capacitor is a Push and Pull Load to the Speaker. Without it.... The Speaker cannot have loud or
audio at all!


I can provide a Link that proves this

Motorola MaxTrac, Radius and GM300 Series Introductory Information

.................................................. ............

CAUTION: DON'T LET THE SMOKE OUT !
The earlier Motorola mobile radio products mostly used push-pull audio power amplifiers and audio output transformers, and drove the speakers as a hot wire to ground. The Maxtrac, Radus, GM300 and many later radios eliminated the audio transformer and they run the the speaker as the push-pull load directly ... both sides floating off of ground. This quirk is significant on your workbench: any audio test equipment that connects to the speaker (such as you would use to make a quieting measurement) must be on the far side of a audio isolation transformer. Motorola has a low-power one as part number SLN6435 in their test equipment catalog (being "test equipment", it's high priced - at about $80), and they also include a cheaper but higher audio power one in every tabletop base station (part number 2580188B01, about $35 in late 2006) since common wireline remote controls expect ground-referenced audio to drive the remote sepakers.
In a pinch you can connect a 2 watt resistor of any value from 8 to 22 ohms to the radio as a speaker load, and use a 600 ohm to 600 ohm line transformer between the radio and the test equipment. I've had good luck with 600 Ohm-to-600 Ohm transformer (like a Triad TY145 - available from Mouser Electronics (p/n:553-TY145P) under $4 as I write this). Note that the audio bandpass characteristics of whatever isolation transformer you use will have to be wider than the audio frequencies you hope to pass through the radio. The Triad TY145 is a broadband audio transformer and if you use that one you won't have to worry about that.

In short, if you ground one of the speaker leads the odds are better than 75-25 that you will let some of the magic smoke out of your radio. So use an audio isolation transformer to prevent this - just put the transformer between the radio and any load that isn't a floating (an ungrounded) stand-alone speaker.
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Old 01-19-2016, 4:51 PM
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Not surprising your obsolete radios are failing, they are old enough to have kids in college. You should serious think about refurbing EVERY cap in those things or consigning them to the scrap heap of history.
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Old 01-19-2016, 5:20 PM
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Quote:
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Not surprising your obsolete radios are failing, they are old enough to have kids in college. You should serious think about refurbing EVERY cap in those things or consigning them to the scrap heap of history.
. Read the rest of his posts... 73, n9zas
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Old 01-19-2016, 7:16 PM
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Quote:
Originally Posted by gewecke View Post
. Read the rest of his posts... 73, n9zas
I did, two and a half years ago when the thread was new. Nothing has changed except we've gotten a few years older, the radios have gotten more decrepit, and I added a stroke to my hospital bills......
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