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ZAXCOM TRX900LA RF problem, help


Bloomdidogoe

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A strange thing happened to my TRX900LANC tonight, it worked normally before.

One of my TRX900LANC keeps showing "no signal" on QRX100, and receive nothing while the UHF frequency set to exactly the same as the TRX900, and signal strength is at full scale. The Led light remains red on QRX100. 

On the TRX900LANC screen, the audio bar works just fine when connected to a microphone, the IFB RX and TX function works fine also. I can monitor the problematic TRX900LA via ERX2TCD. 

The problem is with the UHF signal decode I think. 

Have tried to change the frequency, mode, and checked the encrypting value is set the zero. Swapped the receiver. Re-burn the firmware. Didn't help at all. 

Try with the other TRX900LA, the others works just fine in every way.

TRX firmware version is 8.77
QRX firmware 3.19



Any help?

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When I was having issues pairing my transmitters with new QRX200s, I was told by Zaxcom that encryption is not supported yet with the new beta firmware.  I turned it off and they've been fine.

 

I imagine reimplementing encryption will be pretty high on Zaxcom's update priority list.

 

In your case, I see you've turned encryption off, so that shouldn't be the issue.  It seems you've tried most things you can.  A note worth remembering:  Always make sure to do a power cycle on both units after changing any critical settings.

 

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As Rich also mentioned, did you switch mics? If you are using a Cos-11 (or possibly other mics) the shield needs to be tied to the shell. If the ground gets disconnected, it could totally dropout at just a few feet away. You would still see audio at the transmitter but nothing would get to the receiver.

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You did mention modes, but I'd definitely re-check them as Patrick mentions above. Wrong mode results in exactly the behaviour you described. The modes have different names on different devices, iirc, so it might add to the confusion

I did check all the transmitter and receiver mode are the same. I use US MONO on TRX900, Format normal on QRX100.

 

I remember once I got reception problem, because I incidentally turned on the AES options. Re-check your menu see if any luck:)

 

the AES options on QRX100 is set to off.

As Rich also mentioned, did you switch mics? If you are using a Cos-11 (or possibly other mics) the shield needs to be tied to the shell. If the ground gets disconnected, it could totally dropout at just a few feet away. You would still see audio at the transmitter but nothing would get to the receiver.

I did use COS11D and have them shielded to the shell. I think my problem is RF issue coz the QRX100 receive the other normal TRX900's signal even without mic connected.

 

possibly some more useful suggestions, 

does changing power settings help?

does removing or changing the microphone help?

if it is the only transmitter you have on does it still not work?

 

 

yes, I have three other TRX900, work just fine.

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Do you have another QRX to try receiving the TRX? It seems to me to be an issue with the transmitter. The preamp and ZaxNet features are working, but the UHF isn't. Probably needs a trip back to Zaxcom for repair.

 

Mark O.

I tried with another QRX100, not receiving the TRX either.

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There is a menu setting to shut off the RF board - the the unit can work as a recorder only to save battery power - make sure that the menu is NOT set to recorder only. 

Jack, I've confirmed that Recorder Only Mode is set to off on the problematic TRX900.

The QRX100 gets the UHF signal at full, strong scale from TRX900 when it turns on, but QRX100 can't recognize it, the LEDs light RED and the screen shows NO SIGNAL. 

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I spoke with Howy and he suggested trying to change the output power levels.

If that still doesn't work it may have to be serviced.

Thank you Jack.

 

Some new situations just happened when I want to change the output power level after seeing your post. 

 

The problematic TRX900 was temporally received by QRX100 as normal for 2-3 mins. Then the receiving status was gone suddenly. The LED of QRX100 flashed from green to red for several times before it became all time red.

 

I recorded the moment of losing receiving status with my 788T.

 

 https://www.dropbox.com/s/p0dfj8hk9lwypwn/LOSINGSIGNAL_2.WAV

 

 

 

It seems need to be repaired I think...

 

Is there anything I should know before I sent the repair item back to Zaxcom from outside of the US? My location is in Taiwan.

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Is there anything I should know before I sent the repair item back to Zaxcom from outside of the US? My location is in Taiwan.

yes, have your local dealer do it for you. They should know how to do this. Otherwise, go to a customs office and ask for all relevant forms for a repair shipment. If you don't have that, your TRX will be taxed many times
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