S.E.X. dead in left channel.

hibuckhobby · 2870

« previous next »
Pages: 1   Go Down

0 Members and 1 Guest are viewing this topic.

Offline hibuckhobby

  • Jr. Member
  • **
    • Posts: 23
on: April 13, 2014, 12:22:34 PM
It was fine a couple days ago.  Turned it on today...tubes lit up, but no
left channel sound.  I've given it a close visual inspection, but since I didn't
build it and don't have a schematic...I don't even know where to start.  It
has the CS4 and impedance switches.  No sound at speaker terminals or
left channel on headphone.   Where to begin?
regards,
Hibuck...


Offline hibuckhobby

  • Jr. Member
  • **
    • Posts: 23
Reply #1 on: April 13, 2014, 01:10:56 PM
OK...the "back" two led's are lit...the front two aren't?  Help?


Offline Doc B.

  • Administrator
  • Hero Member
  • *****
    • Posts: 9658
    • Bottlehead
Reply #2 on: April 13, 2014, 04:22:26 PM
Give us voltages, that's always the place to start when LEDs won't light.

Dan "Doc B." Schmalle
President For Life
Bottlehead Corp.

Offline hibuckhobby

  • Jr. Member
  • **
    • Posts: 23
Reply #3 on: April 14, 2014, 04:35:13 AM
OK...given that I have no schematic I have looked up some voltages I should check.
Here is what I have so far:

0A=61.5   0B=0
T15=19.5  T25=19.4
A2=380  B2=0
A5=61.5  B5=0

With my limited knowledge...it seems that one side is testing OK and the other is not.
Where to start looking?
thanks,
Hibuck


Offline Paul Birkeland

  • Global Moderator
  • Hero Member
  • *****
    • Posts: 19750
Reply #4 on: April 14, 2014, 05:17:42 AM
You have a loose power supply connection feeding the left channel, though it is really tough to tell where it might be since we can't be sure which SEX amp you have.

Can you post a photo of the underside of the chassis?

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline fullheadofnothing

  • Global Moderator
  • Hero Member
  • *****
    • Posts: 1487
  • A noble spirit embiggens the smallest man
Reply #5 on: April 14, 2014, 06:50:07 AM
It has to be a 2.1, Paul. Impedance kit can't go in a 2.0, and the 2.0 uses the little C4S boards, so no OA/OB...

Joshua Harris

I Write the Manuals That Make The Whole World Sing
Kit Packer Emeritus

Offline Paul Birkeland

  • Global Moderator
  • Hero Member
  • *****
    • Posts: 19750
Reply #6 on: April 14, 2014, 08:39:31 AM
Ah, yes indeed.

In that case, I would be looking at the red wire that runs to terminal 20.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline hibuckhobby

  • Jr. Member
  • **
    • Posts: 23
Reply #7 on: April 14, 2014, 09:06:11 AM
OK...I have over 360v both to 1A and 1B
ON 0A I have 61.5 v  on 0B I have nothing
and therefore nothing going to B5.
could it be the transistor for the left side on the CS4?
Either th TO22 case or the small round case?  BTW
I have 385v on one side of both LED's as well, but
w/o a schematic I'm lost as to the current flow.

Also...if I have voltage on one side of the LED's...
where are they grounded?  Is it through one
of the transistors or are they a part of the circuit and
possibly blown?

regards,
Hibuck...
« Last Edit: April 14, 2014, 09:44:26 AM by hibuckhobby »


Offline Grainger49

  • Hero Member
  • *****
    • Posts: 7175
Reply #8 on: April 14, 2014, 09:46:50 AM
You have a good side and a bad side.  Compare the components on them and verify the transistor leads are the same.


Offline hibuckhobby

  • Jr. Member
  • **
    • Posts: 23
Reply #9 on: April 14, 2014, 10:12:15 AM
It just about has to be the 5731 transistor.  There is voltage on the emitter pin,
but not on the red wire.  I just redid the solder connection...no difference.
On the "A" Side, there is 370 in and 62 on the wire.
Is my reasoning OK?
HIbuck...


Offline Grainger49

  • Hero Member
  • *****
    • Posts: 7175
Reply #10 on: April 14, 2014, 11:57:35 AM
Can you measure to the trace that the 5731 transistor emitter is soldered to?  This will verify that the emitter is well bonded. 

If that is the last element before the output then the solder joint or wire at OA could be the problem.  (I don't have a manual or even a schematic so I'm at a loss for the circuit layout)


Offline Paul Birkeland

  • Global Moderator
  • Hero Member
  • *****
    • Posts: 19750
Reply #11 on: April 14, 2014, 12:28:05 PM
Quote from: hibuckhobby on April 14, 2014, 10:12:15 AM
It just about has to be the 5731 transistor.  There is voltage on the emitter pin,
but not on the red wire.  I just redid the solder connection...no difference.
On the "A" Side, there is 370 in and 62 on the wire.
Is my reasoning OK?
HIbuck...

Yes, resolder the center pin and you should be good to go.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline hibuckhobby

  • Jr. Member
  • **
    • Posts: 23
Reply #12 on: April 15, 2014, 05:10:10 AM
Sadly, it made no difference.  My primary struggle is that since I
bought this from the person who built it...I have no schematics.
If there is anyone who would forward me a CS4 schematic...that would be
a great place for me to start.
regards,
Hibuck...


Offline Paul Joppa

  • Global Moderator
  • Hero Member
  • *****
    • Posts: 5833
Reply #13 on: April 15, 2014, 05:29:48 AM
I don't suppose there's any chance you can get the manual from the person who built it? The manual has circuits and diagnostic information. If you can't, call or ping Eileen (Bottlehead - More - contact us - shipping status for her email, she's the Queen!) and ask about ordering one.

Paul Joppa

Offline hibuckhobby

  • Jr. Member
  • **
    • Posts: 23
Reply #14 on: April 23, 2014, 03:59:03 AM
through the generosity of a person on another forum, I now have the construction manuals and schematics
for the CS4 and the S.E.X. amp.  I have parts coming and expect to be operational within the next couple
of days.
regards,
Hibuck....


Pages: 1   Go Up
« previous next »