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Old 09-03-2018, 02:58 PM   #41
Gammaray
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Default Re: Electron Kinetics Eagle 2C amplifier problem

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Originally Posted by petehall347 View Post
test the diodes next to where it says bias on the board .
OK, but noob question, should I measure these diodes with or without the main power on? Thanks!
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Old 09-03-2018, 03:18 PM   #42
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Default Re: Electron Kinetics Eagle 2C amplifier problem

you can measure on diode test power off or DC voltage right across each diode powered on .should be around 600mv
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Old 09-03-2018, 04:38 PM   #43
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Default Re: Electron Kinetics Eagle 2C amplifier problem

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you can measure on diode test power off or DC voltage right across each diode powered on .should be around 600mv
OK, Thanks! Should I set the negative probe (DMM) to the green wires as I did for testing the transistors? If so, I can just use the positive probe to place on the diodes to test the voltages. One last question: Does it matter what side of the diodes I check? I'm thinking the anode side, but just want to be certain! Thanks again!
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Old 09-03-2018, 04:56 PM   #44
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Default Re: Electron Kinetics Eagle 2C amplifier problem

one probe on anode the other on cathode .. you are measuring forward voltage drop ...VF
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Old 09-04-2018, 08:03 AM   #45
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Default Re: Electron Kinetics Eagle 2C amplifier problem

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Originally Posted by petehall347 View Post
one probe on anode the other on cathode .. you are measuring forward voltage drop ...VF
Both diodes measured at around .740 DCV
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Old 09-05-2018, 04:49 AM   #46
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Default Re: Electron Kinetics Eagle 2C amplifier problem

not them then .
now test the diodes next to the blue trim pot
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Old 09-05-2018, 02:36 PM   #47
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Default Re: Electron Kinetics Eagle 2C amplifier problem

BTW, did you check the DCV at the speaker terminals as suggested?
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Old 09-05-2018, 02:38 PM   #48
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Default Re: Electron Kinetics Eagle 2C amplifier problem

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not them then .
now test the diodes next to the blue trim pot
Hi Pete! Please pardon my lack of knowledge, but I am unsure which ones around the blue trimmer pots would be the diodes? It looks like all resistors to me. Looking at the blue colored trimmer pot on the photo, there are (2) components to the left side that appear to be resistors, but not sure. Also, to the right side, there are (3) components that also appear to be resistors? Sorry to ask this, but I'm a little weary about placing the DMM probes on something I shouldn't. Just don't want any big zaps..LOL Thanks again!
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Old 09-05-2018, 02:43 PM   #49
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Default Re: Electron Kinetics Eagle 2C amplifier problem

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BTW, did you check the DCV at the speaker terminals as suggested?
Hi Bud! I did check the DCV at the speaker terminals and posted it here earlier in post #28. You may have just overlooked it. No problem sir. Here are the measurements:

Speaker Outputs:

Channel (A)= .001 DCV
Channel (B)= -21.8 DCV and then starts to drop in voltage.

Thanks again Bud. I really appreciate your kindness and knowledge for wanting to help us noobs out!!! Cheers!
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Old 09-05-2018, 03:30 PM   #50
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Default Re: Electron Kinetics Eagle 2C amplifier problem

i missed that offset somehow .. bias is around double what it should be . making me think emitter resistor now .
a schematic would be handy .
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Old 09-05-2018, 03:32 PM   #51
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Default Re: Electron Kinetics Eagle 2C amplifier problem

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Originally Posted by Gammaray View Post
Hi Pete! Please pardon my lack of knowledge, but I am unsure which ones around the blue trimmer pots would be the diodes? It looks like all resistors to me. Looking at the blue colored trimmer pot on the photo, there are (2) components to the left side that appear to be resistors, but not sure. Also, to the right side, there are (3) components that also appear to be resistors? Sorry to ask this, but I'm a little weary about placing the DMM probes on something I shouldn't. Just don't want any big zaps..LOL Thanks again!
4 diodes one resistor
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Old 09-05-2018, 04:17 PM   #52
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Default Re: Electron Kinetics Eagle 2C amplifier problem

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Originally Posted by Gammaray View Post
Hi Bud! I did check the DCV at the speaker terminals and posted it here earlier in post #28. You may have just overlooked it. No problem sir. Here are the measurements:

Speaker Outputs:

Channel (A)= .001 DCV
Channel (B)= -21.8 DCV and then starts to drop in voltage.

Thanks again Bud. I really appreciate your kindness and knowledge for wanting to help us noobs out!!! Cheers!
Sorry, I did not see that. The thread is just getting long to keep track.
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Old 09-05-2018, 07:32 PM   #53
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Default Re: Electron Kinetics Eagle 2C amplifier problem

OK, I measured the diodes by that trimmer pot. Here are the voltages for side (A)
From left to right: .488DCV, .640VDC, .633VDC, .524VDC

Side (B) From left to right: .480DCV, .640VDC, .633VDC, .516DCV

P.S. I don't have a schematic, so not sure what to do now?

Last edited by Gammaray; 09-05-2018 at 07:34 PM..
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Old 09-05-2018, 07:47 PM   #54
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Default Re: Electron Kinetics Eagle 2C amplifier problem

those look good .. on the side with higher base voltages to the outputs does the blue trimmer affect voltage to output transistor bases ? outputs are the large ones .
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Old 09-05-2018, 08:44 PM   #55
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Default Re: Electron Kinetics Eagle 2C amplifier problem

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Originally Posted by petehall347 View Post
those look good .. on the side with higher base voltages to the outputs does the blue trimmer affect voltage to output transistor bases ? outputs are the large ones .
Sorry, but you lost me there? I'm not sure what you are speaking about. Are you saying that I should adjust the blue trimmer pots and check the voltage on the large transistors? If so, I can do that fairly easy with measuring the top transistors marked 2SC2774, but will be more difficult measuring the big transistors located on the bottom.
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Old 09-06-2018, 02:29 PM   #56
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Default Re: Electron Kinetics Eagle 2C amplifier problem

Now I am wondering after all the measurements and instructions I have followed, Can anyone tell me what I should do next? I mean is there any indication from all the measurements thus far as being OK?

It seems like to me that after I had measured the speaker outputs, that they were no where near close. And also those (2) big caps appear to also have an issue with one as far as one not discharging after I grounded a screw driver across the terminals!
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Old 09-10-2018, 01:35 PM   #57
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Default Re: Electron Kinetics Eagle 2C amplifier problem

Looks like this thread has gone to crap..lol..Guess I'll just replace everything on the board!

I imagine that transformer and the larger gauge wires will last another 20 years or so?

Thanks again to budm, petehall347, and vinceroger69 for trying to help out!

Cheers!
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Old 09-10-2018, 02:46 PM   #58
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Default Re: Electron Kinetics Eagle 2C amplifier problem

It is real difficult without schematic, it does have bad problem on that channel with very high offset Voltage.
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Old 09-10-2018, 03:33 PM   #59
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Default Re: Electron Kinetics Eagle 2C amplifier problem

could be a simple resistor or diode .or even poor solder ..
give the board a good looking at for bad solder . then check every resistor comparing both channels . then test diodes 2 ways and transistors 6 ways .. you should see a difference or more in the readings .. if anything is way out remove it and test again ..
check things with power off .
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Old 09-11-2018, 01:29 AM   #60
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Default Re: Electron Kinetics Eagle 2C amplifier problem

It appears to be channel (B) that is bad. I was told that the transistor is not on, and from the voltage levels it looks like it's shorted B/E,

#5(2SC2168) B= -44.8 DCV/ C= -2.27DCV/ E= -44.8 DCV

also channel B has -21V dc at the speaker output, which should be zero volts.
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