Eico 324

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Eico 324

Post by frank1956 on Sun Sep 14, 2014 8:22 pm

Hi all,
Quick question. Since I finished my RCA X551 the other day I decided to re-cap my eico 324 signal generator. I changed all the resistor and the two (2) electrolytic. I found a you tube video on how the electrolytic were done and followed that process since it was straightforward and seemed fairly simple. The processed called for a 5 prong terminal strip,  two (2) 20 mf @ 150 v electrolytic, one (1) silicon rectifier, 1000 PRV 2.5A, and to replace the original 2.2 K resistor with a 2.4 K resistor.

I doubled check the video after I was done and notice that between the 2.8 K resistor and the positive side of the second electrolytic there was what looked like as I call a solder bridge between the pos side of the electrolytic and the hot lead going to the 12AU7 tube. After all was said and done and I turned it on the 2.8 k resistor started smoking What a Face. Needless to say I turn it of and removed the solder bridge, problem solved wrong. Since I have removed the solder bridge between the two the signal generator does not work. Do not want to proceed any further without some advice, any idea!!  Not sure if this make a lot of sense, so I have attached so pic's of what I have done so far. If you would like to see the video https://www.youtube.com/watch?v=I0JdEnKAP78



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Re: Eico 324

Post by frank1956 on Mon Sep 15, 2014 12:05 am

I meant to say the 2.4 K resistor started to smoke!!!
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Re: Eico 324

Post by willy3486 on Mon Sep 15, 2014 8:16 am

Double check your wiring on the tube. From the wiring diagram I found it looks like that red wire should go to r10,r12 and pin 1 of the tube. From what I saw it looks like the cap,diode resistor is right. Is the end of the red wire and the 22k resistor tied to the chassis ground? I kind of looks like it. Did you replace the 2.4k resistor with correct wattage? Double check your work. I have found mistakes I made at times when I go back a second time when something should work.

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Re: Eico 324

Post by frank1956 on Mon Sep 15, 2014 9:31 am

Willy, The end of the red wire and the 22K resistor are tied to the chassis ground. The 2.2 K now replaced with the 2.4 K per the schematic call's for a 1/2 watt, which is what is in there.

Thanks
Frank
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Re: Eico 324

Post by willy3486 on Mon Sep 15, 2014 9:40 am

frank1956 wrote:Willy, The end of the red wire and the 22K resistor are tied to the chassis ground. The 2.2 K now replaced with the 2.4 K per the schematic call's for a 1/2 watt, which is what is in there.

Thanks
Frank

That may be the issue there. Double check the diagram on it. I looked at this diagram and it shows that your red wire is not connected to ground.
eico manual

From what I see the red wire should connect to one end of the r12,r10 and pin 1 on the tube. What may be going on since it is grounded all that current is heating the resistor up causing it to overheat.

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Re: Eico 324

Post by frank1956 on Mon Sep 15, 2014 10:19 am

Here is a pic for better explanation. I doubled checked and everything seem to be correct. I basically touched nothing in that area, just replaced the capacitors and the one resistor.

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Re: Eico 324

Post by willy3486 on Mon Sep 15, 2014 10:52 am

One thing you may want to do is to draw out what you have and compare it to the diagram. Does that terminal have a connection to the piece that holds it? In other words if you ohm out the nut that holds the terminal and the red wire and it reads that may be the issue. If that terminal is connected to the chassis or any ground that may be the issue. Drawing it out may help. It looks to me it is grounded.

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Re: Eico 324

Post by frank1956 on Mon Sep 15, 2014 11:20 am

Per the schematic's I am looking at there are three resistors for the AF oscillator Ext modulation amplifier  i.e. 22 K, 1 K and a 100 K. I see what you are talking about that is for the top tube pin 1 & 2 i.e.470 K and a 270 K resistors.

I have attached a copy of the schematic on one signal page a lot easier to read. Don't worry about the writing, my chicken scratch.

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Re: Eico 324

Post by frank1956 on Thu Sep 25, 2014 12:25 pm

Project completed. Signal generator working!!!! Very Happy
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Re: Eico 324

Post by willy3486 on Thu Sep 25, 2014 7:33 pm

Great news! Glad you got it going. I picked up 2 signal generator heathkits and some other testbox that is beyond repair last Friday. I used the junked ones knobs to go on one of them I fixed. The other generator looks maybe fixable. I like stuff like this.

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Re: Eico 324

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