I'm fairly new to the hobby and am trying my best to learn the ins and out of radio repair by reading books on the subject. One of the major problem areas is finding a good instruction book on how to use my Eico 324 Signal Generator to localize the trouble to a specific stage. I have the Eico instruction manual but I don't know where to set the various dials. Here is a typical instruction from the manual: "Check the speaker and output transformer by applying the full audio output to the primary of the output transformer". I don't know how to apply the full audio output!! Can anyone tell me how to do this??

Greets, Andy.

I haven't worked with a 324 sig gen in more years than I care to admit (showing my age here) but as I recall, there is a variable output attenuator that you may set for various troubleshooting uses.

We used to troubleshoot tube audio with a 200Hz signal, attenuated to minimum output at first. Attenuation was slowly decreased (raising output) 'til the tone was heard.

The Eico user's manual is a basic coverage of what the instrument can do. For specific frequencies and output levels, you may wish to refer to the "electronic cookbooks" of the day that covered tube circuitry.

Hope it helps.

Addendum:

If it's any help, please be very careful when injecting audio-level signals. Back in the early days I ripped up an ancient Jensen loudspeaker in a customer's set by injecting too powerful a signal into the final output stage. I sent the speaker out for rebuild ~ and had to eat the cost.

Suffice it to say I never did that again. :o)

Andy,
I have emailed to you a fairly comprehensive article on Signal Tracing. Good luck......and keep on reading.

Dennis
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:I'm fairly new to the hobby and am trying my best to learn the ins and out of radio repair by reading books on the subject. One of the major problem areas is finding a good instruction book on how to use my Eico 324 Signal Generator to localize the trouble to a specific stage. I have the Eico instruction manual but I don't know where to set the various dials. Here is a typical instruction from the manual: "Check the speaker and output transformer by applying the full audio output to the primary of the output transformer". I don't know how to apply the full audio output!! Can anyone tell me how to do this??

:Andy, I'm in the same boat as you, just purchased same gernerator. Attenuator= volume control, amount of power your putting out, attenuate = vary. They could have said power controler but specialized the language. I haven't used mine yet as I just finished checking wiring and changing electrolic caps and adding three wire plug to chassis. Have to align it now. I also changed the Amphenol connected to the newer type. Whenever using it start at lowest attenuation-output and slowly work up. Pat

:I'm fairly new to the hobby and am trying my best to learn the ins and out of radio repair by reading books on the subject. One of the major problem areas is finding a good instruction book on how to use my Eico 324 Signal Generator to localize the trouble to a specific stage. I have the Eico instruction manual but I don't know where to set the various dials. Here is a typical instruction from the manual: "Check the speaker and output transformer by applying the full audio output to the primary of the output transformer". I don't know how to apply the full audio output!! Can anyone tell me how to do this??

Andy, Pat again, I thought over my answer to your question and realized I was being rather pompous. The generator has an AF output on the lower left front panel. There are two terminal posts there. To check the speaker and output Xfmer what they are saying is set "Signal Sel." sw. to "Ind. Mod AF Out" and connect test leads from the two posts to the two primary leads of the output Xfmer and give it full volume "AF Mod/Output" to 100. I would not do it that way. Start low (10) and work up to the point that you can hear the AF frequency (400cycles per second)coming through the speaker at a reasonable level and stop. You now know its working, why find out how much it will take to burn it out. You can locate the output Xfmer in the schematic and you will have to lift off (un-solder and remove) one wire of primary (coil of Xfmer closest [electrically] to last stage of radio output). On the old sets with the electromagnet speakers in the console the wires are connected with pin type connectors at the speaker and you just pull out the pins and insert the leads from the signal generator. What you are doing is substituting your AF generator for the radio to supply an audio frequency to the primary of the transformer and determining whether the signal correctly passes through the secondary and to the speaker. Lacking the signal generator your only test of the Xfmer is continuity and resistance across the primary and secondary windings which may not detect shorted windings which would change the performance of the Xfmer. If you are checking an electromagnetic speaker you will have to perform this test with the radio on as the power to the magnet on the speaker is supplied by the radio's rectifier. You are probably thing how do I do that when the !@#$%^&* radio ain't working. One possibility is to disconnect secondary of output Xfmer from speaker and use a substitute permenant magnet speaker in its place. This gets complicated doesn't it. Have fun. Pat

I own the 324. I didn't know that its frequencies went all the way down to the audio range. I'll have to check my generator again. It is a nice generator, and is fairly stable. I wouldn't expect perfect calibration, though. I recalibrated mine using a digital AM/FM/shortwave radio. After doing that I learned that getting perfect tracking across the dial is not possible. Now, when I want a certain frequency, I tune to that frequency on my digital radio and then adjust the signal generator accordingly. Rarely does the signal generator's dial say exactly what the real frequency is. A big warning to those who wish to recalibrate their generators: be careful that you don't tune to harmonics. I forgot all of the harmonics. I think that there's one that's about 920 KC below the fundamental, and several that are above. The real thing will of course be stronger than all the rest. The signal meter on my digital radio helps with this, too.

Regarding putting a 3 wire cord on the generator, this is a TERRIBLE idea. I don't know why on earth people do this. The generator is used on all sorts of equipment including AC-DC radios. If the generator's chassis is grounded, as mine was when I got it, you'll see some real sparks when you use it on an AC-DC chassis. What I do is either make sure that both are plugged in the same way and that both are on, or I simply make it a practice to never touch the generator's leads with one hand and the radio with the other. Plugging in the radio the wrong way can also introduce hum problems even if the generator is ungrounded, so it's always a good idea to plug both in the same way. You can also use an isolation transformer on either the generator or the radio.

I assume that the comprehensive info. that was sent to the original correspondant of this thread covered using the generator on RF circuits containing AVC (automatic volume control) circuits. If not, though, it is always best to use the smallest output possible that will give a reading on your meter or a sound in your speaker. Using a higher output will trigger the AVC circuit, which will cancel out any tone amplitude variation that might normally be present while you tune the RF circuits. Keeping the AVC inactive will allow you to hear the results of your tuning up the circuits.

Thomas