Crown CE1000 channel 2 problem/fault indicator -diagnosis

Discussion in 'General Electronics Chat' started by wolf1419, Oct 1, 2009.

  1. wolf1419

    Thread Starter Active Member

    Nov 1, 2008
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    Just was getting into working on my Marshall 8100, but now my Crown CE1000 power amp just went into fault mode(flashing red) on channel2, which mutes the audio...channel1 is fine though.
    Tried with no input & no speaker....same fault(no heat detected, no smoke, no smell, no pop, noises, etc..)...even tried after letting it totally cool......has been running at very low volumes in a studio situation......
    Ohms, speaker cables, etc...all verified as good.
    How do I start my diagnosis without FRYING myself...lots of power in there..(schematic attached)...service manuals found and attached in next post for troubleshooting, safety, etc........
     
    Last edited: Oct 30, 2009
  2. wolf1419

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    Nov 1, 2008
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  3. bertus

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    Hello Ron,

    I just had a quick look in the manual and found this about the RED led:

    [​IMG]

    The fault can have differnt causes as you can see.

    Greetings,
    Bertus
     
  4. wolf1419

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    Nov 1, 2008
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    Hi,
    I got your pics...very nice..thanks for sharing....
    I've read these 5 causes also and would tend to think it's either #3 or #4, as it stays on even when not heated yet, unless the heat sensor is defective(thinking it's hot when it's not).....
    Today was my "actual birthday" so my wife and I are out and about today, some visiting, dining, etc.....having a good day.....I'll probably start with the service manual suggestions for troubleshooting and see if I can determine anything...
     
    Last edited: Oct 31, 2009
  5. bertus

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    Hello Ron,

    Congratulations with your birthday.

    I have looked at the service manual and saw there are some field modofications in chapter 9.
    One of them is for a constant blinking led, some timing has to be changed and some parts to be changed.

    The parts involved are SMD (surface mount devices) that need some care to handle.
    http://www.circuitrework.com/guides/7-0.shtml

    Greetings,
    Bertus
     
  6. wolf1419

    Thread Starter Active Member

    Nov 1, 2008
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    Nice find.....the SMD is new to me, so i'll need to get comfortable with that, and that chapter 9 flashing LED mod could be a problem to check. I'll have to figure out which board, date, version, parts, etc....are in there.

    That's a great place to start!! I'll let you know when I find out what I'm dealing with.....I enjoyed a rather long day yesterday, even walked along the beach(it was beautiful), and now I have to pay for using the energy....I'm really feeling the drain.....so let's see if I can get into this amp soon.....

    I took a little time, got inside, but can't see any #'s for which board, or year CE1000 I have......checked flyback diodes D114, D115, D214, D215 for obvious shorts, as instructed(see 2.3.3 service static check for output device fault)...none found......Thats GOOD!!

    Next I found C121/221 & C124/224(marked 50V, 2.2 uf as shown in schematic), but R174/274, R192/292, R6/18/29 cannot be seen from the top without dismantling the entire amp sections. This is going to be quite a project.....capacitors will be soldered(or glued..?) from the back(not SMD)....

    Just an observation....(no burnt components showing, no bulging capacitors, no smells by using a straw to focus on individual components for anything blatent).....time to give it a rest and ponder.........

    *note: modification for bootstrap 1k/5w resister was in place as shown, so I'm thinking this may have already had some upgrades, or is the newer version.......(figure 9.6 of mod section in question 9-4)...and then checked specs for newer board #102138-9(CE1000), which has the correct capacitors for C121/221 & C124/224 = 2.2uf, 50V, which is what I have in there, so this may not be the problem.....hmmm....(I don't seem to have the the bad board
    #102138-8(CE1000), which had the defective issues............now I'm stumped........no output short, upgraded board, etc......

    Can we begin by discussing and understanding the fault protection circuits and how they sense the issues they are designed to protect, before I get into tearing this all apart..? It seems like something simple may be at play here.......it was all working fine, then just went into fault mode on the CH2, using very low volumes...no heat, etc......This way we can focus on individual circuits in the schematic that affect the fault(which is a nightmare in itself...the service manual appears to have dozens of schematics...which one are we really confident using based on my latest observation that it appears to be the better#102138-9(CE1000)...?
     
    Last edited: Nov 6, 2009
  7. bertus

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    Hello,

    On wich page did you find the most fitting schematic?

    Is it possible to measure the voltage at L102 and L202 (both channels to see the difference) ?
    It may be nessesary to measure it at moment the amp is switched on.

    Greetings,
    Bertus
     
    Last edited: Nov 6, 2009
  8. wolf1419

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    Nov 1, 2008
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    In checking all the different versions(updates) I think we'll be using 102141"M" from pages 561-564(1-3 of 3 sheets) based on what I believe to be the #.....-9 board with the bootstrap update observed, and the updated caps, which points me to the "M" version...so we'll try working with these and see if it makes sense as I go through the stages.....I'll post again when I can get to those voltages.....
     
  9. wolf1419

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    Nov 1, 2008
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    A picture is worth 1000 words, so here's 3000 words(3 pics attached)....L102 is exposed(that's how it was), L202 has cap which doesn't want to come free easily......and there's a view of points that can be accessed from the top.....this will give a better view of what we're dealing with.....before I try anything "live". (would that point to the left of L202 a testing point for the voltage...and all the apparant solder points at the ends of each trace, from the top of board, which attach to components underneath......is that a way around taking this all apart to diagnose even points that are on the back of the PCB to test components?) It may be easier to talk through pictures, parts lists, layouts, and schematics......

    Also, there is a distinct, normal "click sound" after the 4 seconds which is the release of the fault startup mode on CH1, but not happening on CH2 anymore.......do you know which actual component does the actual click/release, so I can pinpoint and listen with my "straw(stethoscope)".....and discuss that circuit.
     
    Last edited: Nov 7, 2009
  10. bertus

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    Hello Ron,

    There are blank spots on the traces.
    These can be used to measure signals at that point.
    I circled the one near the capped coil.

    Greetings,
    Bertus
     
  11. wolf1419

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    Nov 1, 2008
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    That's what I was figuring, and hoping to be correct....:).....the question would be if it matters which side of the inductor I'm measuring would make a difference at this stage of diagnosis.
     
  12. bertus

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    Hello Ron,

    No, that is not that important at the moment.
    I just want to see if there is a DC offset that holds the protection active.

    Greetings,
    Bertus
     
  13. wolf1419

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    Nov 1, 2008
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    OK, not what I expected.....:eek:
    1) 86V DC at L102(the good CH1)..very slowly toward 0V when shut off..takes at least 5+ minutes to drain.
    2) 0V DC at L202(the bad CH2)right from moment of startup.....holding 0V, same when shutoff...
     
  14. bertus

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    Hello Ron,

    Could you check the components Q131, Q132, Q231, Q232 for shorts?
    (I circled them on one channel).
    This must be done without power on the amp.

    Greetings,
    Bertus
     
  15. wolf1419

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    Nov 1, 2008
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    These components are so tight in there, I'm not sure how to get probes in there....can you tell me what your thoughts are on the 86V, 0V, and your thoughts for suspecting Q131, Q132, Q231, Q232...and their function for my knowledge and discussion until I can figure how to physically check them...?
     
  16. bertus

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  17. wolf1419

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    Nov 1, 2008
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    OK, we have +98VCC, -98VCC(high voltage rails vs my last project +15VCC, -15VCC lower voltage rails), so 86V is realistic on CH1 @ L102, and my OV on CH2 @ L202 could be due to a short around Q231/Q232, effectively draining to gnd, or is the little arrow symbol and "dot"(near R323) to the left in that circuit loop the fault "break"(which will actually refer to another part of the schematic...? I'd like to follow the "logic" and reading of this more complex schematic.....
     
    Last edited: Nov 8, 2009
  18. bertus

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    Hello,

    The circuit for DC detection at the output looks familair to a light dimmer circuit.
    I have attached a PDF with how this circuit works.

    The arrow you mention is part of the relays that switces the speaker when everything is OK.

    [​IMG]

    Greetings,
    Bertus
     
  19. wolf1419

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    Nov 1, 2008
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    Thanks for the info on Triacs....kind of deep to get the whole picture, but basically they are similar to a transistor that acts as a "switch or relay" in our case. I had to get very creative and use alligator clip/jumpers attached to stiff wires that I could bend and shape as needed to reach the contacts from the top of the board.....it works...no shorts between any pair in either direction, and MT1 of Q131/Q231 effectively grounded(closed) to chassis, as shown. I also double checked all other 10 points referenced to gnd(no shorts), which helped confirmed my findings......so each side "appears to be OK" in this section of the circuit....the red box you show at K100 would be the black component shown in my pics...? It has 2 lugs visible, and are these the actual switching curcuits that would make the audible "click" when turning on(after 4 seconds) and again at turnoff..?
     
    Last edited: Nov 8, 2009
  20. bertus

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    Hello Ron,

    So you can confirm there is no short from L102 / L202 to ground.
    So we have to find out what other problem channel 2 has.
    There are several temperatures checked.
    And there are connections to the transformer.
    Do channel 1 and channel 2 have seperate transformers?

    Greetings,
    Bertus
     
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