| Author |
Message |
    
Pinger
| | Posted on Sunday, February 02, 2003 - 11:24 pm: | 
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I have a 29LTD and everything works except the TX audio.
Any ideas? |
307
| | Posted on Monday, February 03, 2003 - 4:11 pm: |
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Have you tried another mic?
307 |
Pinger
| | Posted on Monday, February 03, 2003 - 4:38 pm: |
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The mic works fine. I've also tried other mics. I originally thought it was the audio IC, but RX audio is fine. I'm not sure what else to check. I've checked TR19, TR18, and a few others, and they seem to be good. |
307
| | Posted on Monday, February 03, 2003 - 9:07 pm: |
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Is the Audio getting through the Mic Gain Control?..To find out , disconnect the center lead on the Driver so no RF gets in the way and you can look at low level input audio signals on a scope from the mic plug all the way down the chain... |
Ss8541
| | Posted on Tuesday, February 04, 2003 - 12:11 am: |
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an easier way is to just gnd pin 4 of the mic jack. if you have a very loud talkback when mic is keyed and you talk into mic, then the audio is working all the way up to the output of the audio ic. if not, then it is time to start tracing from the input of the audio ic back toward to the mic. |
Pinger
| | Posted on Wednesday, February 05, 2003 - 2:51 pm: |
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i tried the mic jack thing, since i don't have a scope, and the audio is not making it up to the audio IC. Any more suggestions on what to do? |
Ss8541
| | Posted on Wednesday, February 05, 2003 - 7:45 pm: |
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to be honest, from here there are just too many other possibilities to give you a way to check without having a scope or audio detector. there are both passive and active components that could be shorted/bad. |
Pinger
| | Posted on Wednesday, February 05, 2003 - 9:13 pm: |
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pin 4 of the audio IC is the input right?
Is there any way i can get something, or rig up something to detect audio? |
Ss8541
| | Posted on Wednesday, February 05, 2003 - 10:12 pm: |
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no, pin 4 is the rx 'switch'. it gnds the 'return' lead of the spkr during rx so the audio from the ic can be 'heard' through the spkr. gnding pin 4 during tx keeps the return of the spkr grnded so you can hear the modulated audio.
there is an amplified spkr that you can get from radio shack that will work to detect audio all the way down to maybe even the mic level. let me see if i can find the part #. you will also need a cap to use this. |
Pinger
| | Posted on Thursday, February 06, 2003 - 2:05 am: |
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What would be a good oscilliscope to buy? I'm not looking to spend a fortune. Are there any "cheap" ones that are a decent deal? |
Pinger
| | Posted on Tuesday, February 11, 2003 - 1:04 am: |
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C67...just in case anyone wants to know.
It was a 10v 100uf cap.
another one of those "Taiwan" Cobras, if that matters. |
2600
| | Posted on Wednesday, February 12, 2003 - 12:40 am: |
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It's not "Taiwan", it's the calendar. Uniden moved production from Taiwan to the Philippines about 15 years ago. The 10-Volt electrolytics seem to have the shortest life span. Electrolytic capacitors just don't age gracefully. In 5 or 10 years you'll see the same problems in Philippines-made radios, too.
73 |
