Badcaps.net Forum
Go Back   Badcaps Forums > Troubleshooting Hardware & Devices and Electronics Theory > Troubleshooting Audio Equipment
Register FAQ Calendar Search Today's Posts Mark Forums Read

 
Thread Tools Display Modes
Old 09-11-2018, 11:16 AM   #61
budm
Badcaps Veteran
 
budm's Avatar
 
Join Date: Feb 2010
City & State: S.F. Bay area
My Country: USA
Line Voltage: 120V 60Hz
I'm a: Knowledge Seeker
Posts: 34,306
Default Re: Electron Kinetics Eagle 2C amplifier problem

The thread is long so I do not remember if you already test that Transistor already or not and compare it to the working channel. You have one working channel so you can always do the comparison test against working channel.
__________________
Never stop learning
Basic LCD TV and Monitor troubleshooting guides.
http://www.badcaps.net/forum/showthr...956#post305956

Voltage Regulator (LDO) testing:
http://www.badcaps.net/forum/showthr...999#post300999

Inverter testing using old CFL:
http://www.badcaps.net/forum/showthr...er+testing+cfl

Tear down pictures : Hit the ">" Show Albums and stories" on the left side
http://s807.photobucket.com/user/budm/library/

TV Factory reset codes listing:
http://www.badcaps.net/forum/showthread.php?t=24809
budm is online now   Reply With Quote
Old 09-11-2018, 01:52 PM   #62
Gammaray
Senior Member
 
Join Date: May 2010
My Country: U.S.A.
Posts: 120
Default Re: Electron Kinetics Eagle 2C amplifier problem

Sorry for the lengthy thread! Here are the voltages from the transistors I measured from each side:

(CHANNEL A) Top Transistors
#1 Sanken (2SC2774) B=.631 DCV/ C=48.0 DCV/ E=.018 DCV
#2 Sanken (C2168) B=1.22 DCV/ C=47.7 DCV/ E=.627 DCV
#3 Sanken (2SC2774) B=.626 DCV/ C=48.0 DCV/ E=.017 DCV
#4 Sanken (A958) B=46.4 DCV/ C=1.22 DCV/ E=47.3 DCV

(CHANNEL A) Bottom Transistors
#1(2SA1170) B= .603 DCV/ C= -46.55 DCV/ E= -.012 DCV
#2(A958) B= -1.22 DCV/ C= -46.33 DCV/ E= -.600 DCV
#3(2SA1170) B= -.593 DCV/ C= -47.3 DCV/ E= -.002 DCV
#4(2SC2168) B= -44.7 DCV/ C= -1.20 DCV/ E= -44.8 DCV


(CHANNEL B) Top Transistors
#1 Sanken (A958) B= 47.8 DCV/ C= -40.0 DCV/ E=46.1 DCV
#2 Sanken (2SC2774) B= -21.0 DCV/ C= 46.8 DCV/ E= -19.6 DCV
#3 Sanken (C2168) B= -18.8 DCV/ C=46.8 DCV/ E= -18.9 DCV
#4 Sanken (2SC2774)B= -18.75 DCV/ C=46.9 DCV/ E= -19.4 DCV

(CHANNEL B) Bottom Transistors
#5 (2SC2168) B= -44.8 DCV/ C= -2.27 DCV/ E= -44.8 DCV
#6 (2SA1170) B= -1.15 DCV/ C= -45.9 DCV/ E= -.63 DCV
#7 (A958) B= -1.9 DCV/ C= -46.7 DCV/ E= -1.22 DCV
#8 (2SA1170) B= -1.42 DCV/ C= -46.1 DCV/ E= -.75 DCV
Gammaray is offline   Reply With Quote
Old 09-11-2018, 02:06 PM   #63
budm
Badcaps Veteran
 
budm's Avatar
 
Join Date: Feb 2010
City & State: S.F. Bay area
My Country: USA
Line Voltage: 120V 60Hz
I'm a: Knowledge Seeker
Posts: 34,306
Default Re: Electron Kinetics Eagle 2C amplifier problem

If you suspect that E-B junction is shorted then you should be able to use Ohm meter to check the resistance between E and B pin if the suspect transistor.
budm is online now   Reply With Quote
Old 09-11-2018, 07:23 PM   #64
Gammaray
Senior Member
 
Join Date: May 2010
My Country: U.S.A.
Posts: 120
Default Re: Electron Kinetics Eagle 2C amplifier problem

Quote:
Originally Posted by budm View Post
If you suspect that E-B junction is shorted then you should be able to use Ohm meter to check the resistance between E and B pin if the suspect transistor.
OK, I will do that and post the resistance. Should I discharge the caps before I take a measurement of the transistor's resistance?

Thanks!
Gammaray is offline   Reply With Quote
Old 09-11-2018, 10:06 PM   #65
budm
Badcaps Veteran
 
budm's Avatar
 
Join Date: Feb 2010
City & State: S.F. Bay area
My Country: USA
Line Voltage: 120V 60Hz
I'm a: Knowledge Seeker
Posts: 34,306
Default Re: Electron Kinetics Eagle 2C amplifier problem

Quote:
Originally Posted by Gammaray View Post
OK, I will do that and post the resistance. Should I discharge the caps before I take a measurement of the transistor's resistance?

Thanks!
Yes! discharge the caps and then take the Voltage reading on the discharged caps to make sure it is discharged.
budm is online now   Reply With Quote
Old 09-12-2018, 03:58 AM   #66
Gammaray
Senior Member
 
Join Date: May 2010
My Country: U.S.A.
Posts: 120
Default Re: Electron Kinetics Eagle 2C amplifier problem

I measured that transistor (2SC2168) from B to E and got 1.292 M ohms..Does this seem bad?

Last edited by Gammaray; 09-12-2018 at 04:01 AM..
Gammaray is offline   Reply With Quote
Old 09-12-2018, 09:52 AM   #67
R_J
Badcaps Veteran
 
Join Date: Jun 2012
City & State: ☻
My Country: Canada
I'm a: Professional Tech
Posts: 3,026
Default Re: Electron Kinetics Eagle 2C amplifier problem

Not really, but
Read post #61 again. and check other parts the same way, you may be suprised at what you will find that way.
R_J is offline   Reply With Quote
Old 09-12-2018, 12:58 PM   #68
budm
Badcaps Veteran
 
budm's Avatar
 
Join Date: Feb 2010
City & State: S.F. Bay area
My Country: USA
Line Voltage: 120V 60Hz
I'm a: Knowledge Seeker
Posts: 34,306
Default Re: Electron Kinetics Eagle 2C amplifier problem

Quote:
Originally Posted by R_J View Post
Not really, but
Read post #61 again. and check other parts the same way, you may be suprised at what you will find that way.
Also in post #4.
budm is online now   Reply With Quote
Old 09-12-2018, 09:17 PM   #69
Gammaray
Senior Member
 
Join Date: May 2010
My Country: U.S.A.
Posts: 120
Default Re: Electron Kinetics Eagle 2C amplifier problem

Would it be ok to take the pcb off from the amp chassis and do some resistance comparisons? I mean is this a good way to find faulty components without worrying about if I may accidently touch some live/hot and zap me or something else?
Gammaray is offline   Reply With Quote
Old 09-14-2018, 10:36 AM   #70
Gammaray
Senior Member
 
Join Date: May 2010
My Country: U.S.A.
Posts: 120
Default Re: Electron Kinetics Eagle 2C amplifier problem

bump
Gammaray is offline   Reply With Quote
Old 09-14-2018, 11:07 AM   #71
budm
Badcaps Veteran
 
budm's Avatar
 
Join Date: Feb 2010
City & State: S.F. Bay area
My Country: USA
Line Voltage: 120V 60Hz
I'm a: Knowledge Seeker
Posts: 34,306
Default Re: Electron Kinetics Eagle 2C amplifier problem

You are taking the resistance reading so the unit should not be powered in the first place so I do not see how you will be zapping anything once the filter caps are discharged and the unit is not plugged in.
budm is online now   Reply With Quote
Old 09-14-2018, 01:15 PM   #72
redwire
Badcaps Veteran
 
Join Date: Dec 2010
City & State: Alberta
My Country: Canada
Posts: 1,076
Default Re: Electron Kinetics Eagle 2C amplifier problem

If you pull the board out, a schematic can get drawn up given some good pictures of the back side. The front pics have some areas I can't see.
Sometimes it's easier to sketch it one and then troubleshoot.
redwire is offline   Reply With Quote
Old 09-16-2018, 07:09 AM   #73
Gammaray
Senior Member
 
Join Date: May 2010
My Country: U.S.A.
Posts: 120
Default Re: Electron Kinetics Eagle 2C amplifier problem

Quote:
Originally Posted by budm View Post
You are taking the resistance reading so the unit should not be powered in the first place so I do not see how you will be zapping anything once the filter caps are discharged and the unit is not plugged in.
OK, I see. So would I have to de-solder these components to check for resistance, or can I leave them mounted to the pcb and check resistance?
Gammaray is offline   Reply With Quote
Old 09-16-2018, 07:10 AM   #74
Gammaray
Senior Member
 
Join Date: May 2010
My Country: U.S.A.
Posts: 120
Default Re: Electron Kinetics Eagle 2C amplifier problem

Quote:
Originally Posted by redwire View Post
If you pull the board out, a schematic can get drawn up given some good pictures of the back side. The front pics have some areas I can't see.
Sometimes it's easier to sketch it one and then troubleshoot.
Thanks, but not sure how I could draw up these traces for the schematics. Seems to be a little out of my noob hands..LOL
Gammaray is offline   Reply With Quote
Old 10-14-2018, 06:08 PM   #75
electricboyo
Member
 
electricboyo's Avatar
 
Join Date: Mar 2013
City & State: Urbana Illinois
My Country: USA
Line Voltage: 120VAC 60Hz
I'm a: Hardcore Geek
Posts: 26
Default Re: Electron Kinetics Eagle 2C amplifier problem

What we need are very sharp clear photos of both side of the PC board. If you remove the mounting screws from all the power transistors and the input and output jacks then you should be able to lift the PC board from the heat sinks so that both front and rear of the PC board can be seen.
The circuit design of this amplifier is somewhat unusual. Some of us who have worked on audio amplifiers for years might be able to tease out its schematic from looking at a really good set of photos of this PC board.
Because you have one channel that works it should be feasible to fix the other channel. The problem could be that just 1 component is bad.
electricboyo is offline   Reply With Quote
Old 10-15-2018, 03:52 PM   #76
electricboyo
Member
 
electricboyo's Avatar
 
Join Date: Mar 2013
City & State: Urbana Illinois
My Country: USA
Line Voltage: 120VAC 60Hz
I'm a: Hardcore Geek
Posts: 26
Default Re: Electron Kinetics Eagle 2C amplifier problem

I suggest checking the value of all resistors on the PC board. Do this with power off and with an ohmmeter. Resistors can fail in the "open circuit" state without looking burnt or damaged.

Because there are unusual DC voltages on the faulty channel I recommend that you should only apply AC mains power to the amplifier through a "dim bulb" tester. This is a conventional incandescent 120V light bulb either 60W or 100W which is wired in series with the AC power source. This can be made with a light bulb socket and an old extension cord. Cut the hot wire of the extension cord and connect the cut ends to opposite sides of the light bulb socket. Typically the light bulb will be bright when the amplifier is first powered up and then it should get dim after the large power supply capacitors charge up. there are other postings on the forum for ''dim bulb tester" that will provide more detail about constructing and using it.

-EB
electricboyo is offline   Reply With Quote
Old 10-18-2018, 10:26 AM   #77
electricboyo
Member
 
electricboyo's Avatar
 
Join Date: Mar 2013
City & State: Urbana Illinois
My Country: USA
Line Voltage: 120VAC 60Hz
I'm a: Hardcore Geek
Posts: 26
Default Re: Electron Kinetics Eagle 2C amplifier problem

Based on your previous voltage measurements I suggest checking all 4 of the large power resistors connected between the emitters of the channel B output transistors. One or more of these resistors is open. Or else there is a bad solder connection or broken foil on the PC board.

Under normal conditions the emitters of all 4 large power transistors should be within +/- 50 mV of each other, and this should also be very similar to the DC voltage appearing at the red output terminal post on the rear of the panel for this channel.

Ideally the DC voltage on the red output terminal post should be less than +/- 10 mV.

EB
electricboyo is offline   Reply With Quote
Old 10-20-2018, 11:55 PM   #78
electricboyo
Member
 
electricboyo's Avatar
 
Join Date: Mar 2013
City & State: Urbana Illinois
My Country: USA
Line Voltage: 120VAC 60Hz
I'm a: Hardcore Geek
Posts: 26
Default Re: Electron Kinetics Eagle 2C amplifier problem

After looking at your photos of the PC board again up-close I am thinking perhaps some of the power transistors for the bad channel aren't actually soldered to the PC board. Or rather, their solder connections broke off. As far as I can tell there isn't much of anything mechanically holding the PC board except for the soldered pins of the large power transistors and the speaker output binding posts. I don't see any bolts or screws holding the PC board.

So, seriously, as suggested by an earlier post, it is really important to unbolt all of the power transistors from the heat sink and the pull out the PC board so you can inspect the back side of it. You may have to unbolt or unsolder the 4 speaker ouput binding posts in order to remove the PC board.

EB
electricboyo is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump



Badcaps.net Technical Forums 2003 - 2018
Powered by vBulletin ®
Copyright ©2000 - 2018, Jelsoft Enterprises Ltd.
All times are GMT -6. The time now is 05:35 PM.

Did you find this forum helpful?