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Thread: Anyone have the diagrams for the older Audio Centron speaker crossover boards?

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    Anyone have the diagrams for the older Audio Centron speaker crossover boards?

    I have an AC-H15EV speaker that came in with a blown midrange horn, which is an EV horn in this case, not a cheap diaphragm. Well, we get the diaphragm in it, and now we have a horn that tries but it only puts out sound if it peaks, and then it's just a bit of distortion, so I am guessing there's something wrong on the crossover board. Our service tech used to have all the SLM schematics and service manuals, but he lost them in a fire a couple years back, so I don't have access to them anymore. If anyone has it and could post it up, I'd appreciate it. I have already trawled through all the places I normally check for schematics and haven't found much Audio Centron stuff at all...

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    Senior Member Enzo's Avatar
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    Some thoughts.

    Audio Centron was the Crate pro audio line. Loud technologies now owns the Crate lines. COntact Loud and ask if they have the information.

    Meanwhile, the crossover is not all that complex. If you cannot eyeball the signal path, you ought to be able to trace it out and draw up a diagram. You will probably have resistors, caps, and inductors, and maybe a light bulb. Unless they are visibly melted or burnt, the inductors rarely fail, other than to break free of their solder, or maybe a wire end breaks off. Caps go open, they go short, they break free of their solder, or break a wire off. The resistors go open, then break free, break wires. And the bulbs, they burn out, the socket fails, or the wiring breaks free.

    Those are all things that are fairly easy to check.
    Education is what you're left with after you have forgotten what you have learned.

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    Senior Member Enzo's Avatar
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    Oh, and if it has biamp jacks, make sure the cutout contacts inside those jacks are making good continuity. If you do have biamp jacks, plug the amp into the horn biamp jack - keep the levels low - and see if it works that way. If so, then the jack is suspect.


    If you find the drawing for Crate CE-15EV, does it look like yours?
    Education is what you're left with after you have forgotten what you have learned.

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    Quote Originally Posted by Enzo View Post
    Oh, and if it has biamp jacks, make sure the cutout contacts inside those jacks are making good continuity. If you do have biamp jacks, plug the amp into the horn biamp jack - keep the levels low - and see if it works that way. If so, then the jack is suspect.


    If you find the drawing for Crate CE-15EV, does it look like yours?
    The CE-15V does look like mine, I saw a photo of one earlier, it's a 3-way with a 15" EV woofer, a pretty good size EV midrange horn, and a Beyma tweeter horn with a "buttcheek" lens on it. I have the crossover out of the cab, I just can't make out all the values on the parts that are on it... the highs try to work but they only sputter a little bit, and even then, only when I turn the signal up a good bit. They don't work with the direct in jack to the mid/high either.

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    Senior Member Enzo's Avatar
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    Um, we replaced the diaphragm in the horn, but did we conect the thing to some other corssover or otherwise run sound through it away from this cab/crossover? Just to verify the driver itself has no issues.

    VAlues are great, but they usually don't wander. open/short/broke is the issue, not wrong value, as a rule. If signal can;t get through a cap, I don;lt worry too much what value it is. I mean yes it matters for freqs, but when we are just looking for where the problem is, the cap works or it doesn't. (or resistor or inductor)

    I usually put a crossover on my bench, plug the output from some amp playing music, then I use my bench speaker (full range speaker) with a couple clip wires to follow the signal through the crossover. I know we are chasing mids , but even if it were highs, I can listen to my full range and hear the action of the crossover. I connect one side to common, then step the other lead through teh circuit. Usually we find teh step where it dies.
    Education is what you're left with after you have forgotten what you have learned.

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    Quote Originally Posted by Enzo View Post
    Um, we replaced the diaphragm in the horn, but did we conect the thing to some other corssover or otherwise run sound through it away from this cab/crossover? Just to verify the driver itself has no issues.

    VAlues are great, but they usually don't wander. open/short/broke is the issue, not wrong value, as a rule. If signal can;t get through a cap, I don;lt worry too much what value it is. I mean yes it matters for freqs, but when we are just looking for where the problem is, the cap works or it doesn't. (or resistor or inductor)

    I usually put a crossover on my bench, plug the output from some amp playing music, then I use my bench speaker (full range speaker) with a couple clip wires to follow the signal through the crossover. I know we are chasing mids , but even if it were highs, I can listen to my full range and hear the action of the crossover. I connect one side to common, then step the other lead through teh circuit. Usually we find teh step where it dies.
    Ok, here's what I did after I posted this afternoon. Your earlier post reminded me how much time our old tech used to spend re-soldering stuff from SLM because of the original solder joints often not being done hot enough, so I re-soldered every connection on the board, which only took a couple minutes as there are only about 25 solder joints on the entire board.

    I did test the driver and it worked before I put it in the box. Also, the highs and mids are both not working. I didn't test the high freq. horn, but our tech did a couple weeks ago and he said it was OK. He has been sick with the flu this week and working from home, and he borrowed my personal meter from me, so I am poking around in it without a meter, just looking for something obvious. I have a second meter, if I can find the second lead for it, I can fire it up and actually start testing stuff. I may have to dremel apart a banana plug tomorrow if I can't find the lead. I'm wondering if I didn't actually take Bill 3 of my meter leads instead of just a pair, since I can only find one of the pair for the backup meter...LOL. It has sort of been a week around here.

    I guess tomorrow I will fire it up on the repair bench as you mentioned and see what I can get it to do by following the traces. Then again, maybe I'll luck out and Bill will be feeling better, but I sort of doubt it from how he sounded on the phone today. Apparently the flu that's going around this year is pretty rough.

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    Solved it this morning. I made a new probe for my backup meter and proceeded to prod around checking continuity, and it turns out the bulb was bad. It's odd, because looking at the bulb, you can clearly see the filament is still stretched across the two contact points in the bulb and making contact, but the continuity is obviously broken somewhere else in the bulb, as it reads dead as a doornail when you take the meter to it. Swapped the bulb, got a reading, put the board into the cab and fired it up and it now works as it should. Thanks for all the suggestions, and Enzo, thanks for reminding me to check the bulb anyway, because I probably wouldn't have, considering I thought it was good because I can see the element still making contact. Glad to have this one out of the way.

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    "Never think of a reason to NOT check something"
    Enzo Rule #4.

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    Senior Member Enzo's Avatar
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    I have just GOT to learn those rules...


    In my junior high shop class, the teachers favorite rule was:

    Don't build your wall with putty full of goof-off sand.

    I don't know that any of my rules can top that.
    Education is what you're left with after you have forgotten what you have learned.

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