Electron Kinetics Eagle 2C amplifier problem

[Gammaray]

I have an older Electron Kinetics Eagle 2C amp from the early 90's. It was assembled and inspected around mid December, 1992. One channel has gone out. I tried contacting the company through email, and also called, but have yet to get an answer! This has been a couple of weeks now. I have also tried searching for a schematic for this amp, but no luck!

I'm thinking it may be a bad cap or caps, and also wondering if the transistors may need to be changed as well? The transistors that were used in this amp were from a Japanese company called Sanken. They are still in business, but I'm not sure if they still carry the OEM transistors used in this amp. I would guess that they should have a direct replacement. I will write to them and ask.

They have 2 large caps that run in series. I took them out and made sure that they were discharged. I proceeded to check them with my Fluke DMM for capacitance, but I realized that these big caps are 80,000mfd/50V. Not sure what I can do to see if they are still good or bad?

Has anyone ever upgraded these older Eagle amps, or may know what I may do to fix the problem? Any info or help would be greatly appreciated! I just want to get it up and running again in 2-channel!

Thanks in advanced!

[budm]

That is a great amp you have there, designed by John G. Iverson the founder of the company.
The two caps are for the +/- power supplies. Since one channel is still working then no need to check those filter caps for now.
You should upload good clear pictures the inside of the unit so we can see the layout of the unit.
Are the SANKEN output Transistors shorted or what? If they shorted out it would have caused the main fuse to blow by now.
There are small lytics caps that should be by now for unit that old.
The way the boards are mounted are not easy to do the test with power applied.

[Gammaray]

HI bud. I do have some photos of some of the board and components. I can take more if needed. I had heard that Mr. Iverson had suddenly vanished after he had an encounter with the FBI years ago..lol Not sure what that was all about, but then again, that is what I had read. May just be hear say!

I'm not really sure how I could test the big caps? My DMM only goes to 10,000mdf. I have checked the fuses, and they are all OK. I have removed both large caps, as to get to the components on the board. You are correct as it will be a little difficult if I have to remove the main board from the amp chassis. But I believe I can do it. The large transformer must be removed next, along with the bridge rectifier and perhaps some de-soldering. What do you think would be best in this case? Should I try and change all of the components, like the caps, resistors, diodes, FET's, and wires? Thanks again Bud!

[budm]

1) As I indicated, no need to check the big caps or the rectifier since one channel is working.
2) Since you have two amplifiers, one is working and one is not then you can do the Voltage comparison readings between good amp and bad amp, just have to be careful not to slip the probes.
3) You can also do the resistance comparison readings too.
4) I see speaker fuses so check them out: https://www.badcaps.net/forum/attach...3&d=1535524223.
5) Make sure to put the wires back on correctly for those two filter caps!

[Gammaray]

Well I did try and check both big caps after taking them out and I have read where you can set the DMM on around 2000K ohms and with the probes one way the ohms will rise, then with the probes the opposite way, the ohms will decrease. I'm not sure if this works well or not, but one cap does that, and the other one does not. That's why I wanted to be certain that both caps were good!

If I do put the big caps back in and connect them, it will be difficult to test voltages. Perhaps I should do the resistance check first? If so, am I only going to be reading the values on all of the resistors?

Thanks!

[budm]

Again, as I already indicate, do not wasting time right now checking the filter caps, you should spend time figure out why one channel works and another channel does not work, once you get them working then you can spend the money replacing the filter caps and other Lytics caps.
So did you check the speaker fuse as suggested?

[Gammaray]

Originally Posted by budm

Again, as I already indicate, do not wasting time right now checking the filter caps, you should spend time figure out why one channel works and another channel does not work, once you get them working then you can spend the money replacing the filter caps and other Lytics caps.
So did you check the speaker fuse as suggested?

Hi Bud! Sorry for late reply back! I did check the 2 fuses located on the board and they are good. So what would be the next step?

[budm]

I already suggest that you do Voltage and resistance reading comparison.

[Gammaray]

Originally Posted by budm

I already suggest that you do Voltage and resistance reading comparison.

Please excuse my lack of knowledge, but I am not sure what I need to measure as for as the voltages are concerned! Should I check any components first for resistance before I put the big caps back in? It is very tight to get to the components once the caps are hooked back up.

[budm]

You can start by check the checking the Voltages on those SANKEN output transistors against circuit GND.

[Gammaray]

So I would need to connect the big caps back, then I would use the ground probe clipped on to the chassis? If this is correct, then it would be OK to use the red probe to each of the legs on the transistors to see what voltage they are showing on each side? I'm not really sure if I can test the Sanken transistors on the bottom as those big caps may prevent this.

[budm]

Yes, you will need o hook everything back up and power up the unit, you can put your meter black probe to where the two green wires are attache to the filter caps.
As I indicated before, this is not easy unit to work on. When I work on something like this I will extend the wires so they are longer so it will allow me to get to the test point.

[petehall347]

tape up your meter probes so just the tip is showing ..this is for when you slip ..
on those outputs B should be about + or- 600mv .
C rail voltage + - same voltages as across each of those big caps .
E should read very low mv.s ..ideally 0v but rarely is the case .

[Gammaray]

Originally Posted by petehall347

tape up your meter probes so just the tip is showing ..this is for when you slip ..
on those outputs B should be about + or- 600mv .
C rail voltage + - same voltages as across each of those big caps .
E should read very low mv.s ..ideally 0v but rarely is the case .

Hi Pete! I'm really kind of a noob here, so please forgive any noob type questions. I don't have a degree in electronics, but I do find this very interesting. I just know a little, but would like to improve my knowledge to get a better understanding of trouble-shooting these components to fix them.

So, that being said, it is my understanding from budm to use my DMM to check resistance and voltages. I should use my ground probe to the green wires on the filter caps, then start checking the Sanken transistors for voltages using the red probe. I assume that I should check the 3 pins that are on these transistors?
I'm not really sure what you are saying when you say check outputs B, and C rail voltage and E?

[vinceroger69]

B C E means base, emitter, collector pins on the transistors basically see if you can read the writing on the transistor then look for a data sheet for the transistor it will then show a picture of what each pin does,maybe in the mean time start watching some youtube videos on how to test transistors/mossfets/diodes/resistors the videos do help this is how im learning.

[Gammaray]

Originally Posted by vinceroger69

B C E means base, emitter, collector pins on the transistors basically see if you can read the writing on the transistor then look for a data sheet for the transistor it will then show a picture of what each pin does,maybe in the mean time start watching some youtube videos on how to test transistors/mossfets/diodes/resistors the videos do help this is how im learning.

Thanks! I should have thought about that a little harder..lol..I was thinking on the lines of B=Blue, but couldn't come up with any colors for C and E..hehehe

Those are older transistors, so I will google and see what I can come up with. I also have been looking at some youtube videos, guess I need to continue searching for some that are more easy to understand!

[vinceroger69]

hey im 49 its harder too understand as you get older lol but watch a couple of videos it certainly helps and with the help on this forum it makes it even easier for us too understand/fault find it nice that people take the time too help us with our projects/teaching us tests etc.

[Gammaray]

Well I'm a little older, but thankfully I still have a fairly good understanding.lol
Do you have any videos that you recommend for me to watch? Also, I have searched around Google for the B,C,E info on the Sanken transistors I have in this Eagle amp, but can't seem to find anything. I have also looked on the Sanken website, but that number on the transistor can't be found. I am wondering if they would have a direct replacement transistor?

[vinceroger69]

whats the number on the transitor?

[Gammaray]

I have Sanken 2SC2774 with 590 marked below that. Also Sanken 2SA1170 with 4NY below that. Some of the smaller sized ones are marked C2168 with 490 below that. Another smaller one is A958 with 55Y below that. These smaller ones appear to be Sunken as well with a SK on the top.

I did post some photos in post #3 here if you were interested in taking a look. Thanks again!