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Author Topic: Signal generator/ signal tracer  (Read 5788 times)
ELMER
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Posts: 18




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« on: August 08, 2013, 09:07:06 AM »

1. Could someone point out to me how they work?
Do you inject the signal and then use the tracer in the circuit to find the problem?

2. Has anyone built either from scratch or from a kit?

I am trying to learn the proper way to check the audio circuit.

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W9GB
Member

Posts: 2616




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« Reply #1 on: August 08, 2013, 09:27:12 AM »

TROUBLESHOOTING RECEIVERS
by WB6NVH
The four methods of troubleshooting are:
1. Circuit Disturbance
2. Signal Substitution
3. Signal Tracing
4. Measurement of Circuit Parameters
http://www.wb6nvh.com/GE/Trouble.pdf

Elliott Sound Products (ESP)
Troubleshooting & Repair Guide
http://sound.westhost.com/troubleshooting.htm

Billm Audio
Troubleshooting your Audio Amplifier with signal tracing
http://billmaudio.com/wp/?page_id=1254

Supporting VIDEO Instruction on YouTube
http://youtu.be/6dwsAhe63cw

Notes on the Troubleshooting and Repair of Audio Equipment and Other Miscellaneous Stuff
Version 3.50 (17-Apr-2009)
Copyright © 1994-2013
Samuel M. Goldwasser
See the Sci.Electronics.Repair FAQ
http://www.repairfaq.org/sam/audiofaq.htm
« Last Edit: August 08, 2013, 09:36:00 AM by W9GB » Logged
KE3WD
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Posts: 5694




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« Reply #2 on: August 08, 2013, 02:26:23 PM »

Use of signal tracer, either RF or AF type, is typically done by starting at the output of the circuit and working your way backwards on the signal path of a dead receiver until you find the point where you detect life.  The stage with the problem then would be the stage immediately following that point.  

The signal generator, on the other hand, can be helpful in doing the above by allowing the technician to inject a known signal into the antenna input of the receiver to look for with the signal tracer, but most of the time I find that simply hooking up some sort of antenna, even a few yards of wire laid out on the floor, can yield enough signal to use my signal tracer in the same fashion.  

The Sig Gen, of course, is also the tool needed for alignment of RF and IF stages.  Also can be quite handy when dealing with lack of RF sensitivity problems, here we can attenuate the signal generator's signal injected into the antenna and thus compare sensitivity of the unit under test to published sensitivity specs, often very handy for finding out if the first stage RF tube or transistor is not up to snuff, things like that. 

Use of Signal Tracer is somewhat an oldschool method, dating from a time when the purchase of a good oscilloscope was something that dealt a lot bigger blow to the finances than the situation today.  Today, I use the o'scopes at the benches as my Signal Tracer maybe 90% of the time.  Being able to see the signal often will show other problems as well, such as excessive AC ripple, or the wave riding on DC that should not be at that point, a signal that is supposed to be a lone sinewave but has harmonics on it that should not be there, etc. 


73
« Last Edit: August 08, 2013, 02:29:15 PM by KE3WD » Logged
ELMER
Member

Posts: 18




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« Reply #3 on: August 09, 2013, 11:24:41 AM »

Thank you both very much for your response, this is exactly what I was looking for.
Enjoy your weekend.
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VU2NAN
Member

Posts: 245




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« Reply #4 on: August 19, 2013, 11:14:16 PM »

Hi Elmer,

Either an audio signal injector or an audio signal tracer may be used to troubleshoot audio stages.

An audio signal injector is used to inject an audio signal to preceding stages with the speaker as monitor. The stage at which the output ceases is the defective stage.

A signal tracer does the reverse. Its basically an audio amplifier with its own speaker and is used to probe the output of each succeeding stage to isolate the defective one.

Here's an old homebrew audio signal injector.

http://nandustips.blogspot.in/2012/07/audio-signal-injector.html

73,

Nandu.

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