Electron Kinetics Eagle 2C amplifier problem

**Gammaray** · 09-03-2018, 01:58 PM

Re: Electron Kinetics Eagle 2C amplifier problem

Originally posted by petehall347

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!

**petehall347** · 09-03-2018, 02:18 PM

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

**Gammaray** · 09-03-2018, 03:38 PM

Re: Electron Kinetics Eagle 2C amplifier problem

Originally posted by petehall347

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!

**petehall347** · 09-03-2018, 03:56 PM

Re: Electron Kinetics Eagle 2C amplifier problem

one probe on anode the other on cathode .. you are measuring forward voltage drop ...VF

**Gammaray** · 09-04-2018, 07:03 AM

Re: Electron Kinetics Eagle 2C amplifier problem

Originally posted by petehall347

one probe on anode the other on cathode .. you are measuring forward voltage drop ...VF

Both diodes measured at around .740 DCV

**petehall347** · 09-05-2018, 03:49 AM

Re: Electron Kinetics Eagle 2C amplifier problem

not them then .
now test the diodes next to the blue trim pot

**budm** · 09-05-2018, 01:36 PM

Re: Electron Kinetics Eagle 2C amplifier problem

BTW, did you check the DCV at the speaker terminals as suggested?

**Gammaray** · 09-05-2018, 01:38 PM

Re: Electron Kinetics Eagle 2C amplifier problem

Originally posted by petehall347

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!

**Gammaray** · 09-05-2018, 01:43 PM

Re: Electron Kinetics Eagle 2C amplifier problem

Originally posted by budm

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!

**petehall347** · 09-05-2018, 02:30 PM

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 .

**petehall347** · 09-05-2018, 02:32 PM

Re: Electron Kinetics Eagle 2C amplifier problem

Originally posted by Gammaray

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

**budm** · 09-05-2018, 03:17 PM

Re: Electron Kinetics Eagle 2C amplifier problem

Originally posted by Gammaray

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.

**Gammaray** · 09-05-2018, 06:32 PM

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?

**petehall347** · 09-05-2018, 06:47 PM

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 .

**Gammaray** · 09-05-2018, 07:44 PM

Re: Electron Kinetics Eagle 2C amplifier problem

Originally posted by petehall347

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.

**Gammaray** · 09-06-2018, 01:29 PM

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!

**Gammaray** · 09-10-2018, 12:35 PM

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!

**budm** · 09-10-2018, 01:46 PM

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.

**petehall347** · 09-10-2018, 02:33 PM

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 .

**Gammaray** · 09-11-2018, 12:29 AM

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.

Electron Kinetics Eagle 2C amplifier problem

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