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October 2006
Posts: 7
Location: Austin, Texas | Hello All,
I just purchased a Breadwinner from craigslist here in Austin. I could not believe my eyes when I saw that posting. I have been looking for one of these guitars for a while and suddenly there it was, I had to get it.
Anyway, although the guitar is in great shape, I am having trouble with the electronics. The tone knob doesn't seem to do anything and the Notch filter switch just makes signal even weaker than it already is. I took the electronic board out and it looks like there was a modification made to it. There are a cople of extra wires that I don't think are original but it looks like they have been there a long time. I took a picture it is here...
http://www.flickr.com/photos/13965576@N00/275496622/
Any help in figuring this out would be great. I have the schematic from the breadwinner fan page and I am slowly going through the circuit now, but any help you guys can offer would be great. thanks
Julio |
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Joined:
December 2001
Posts: 7222
Location: The Great Pacific Northwest | Basically they bypassed the pre-amp, sortof.. Remove those two jumper wires. They don't belong. Someone may have just done this to bypass the pre-amp without destroying it, so just remove them and see if the pre-amp works. And remember the selector switch is BOTH-Bridge-Neck not the normal Bridge-BOTH-Neck. |
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October 2006
Posts: 7
Location: Austin, Texas | Excellent, thanks for the help. I will remove those wires and check the rest of the electronics. hopefully, that is all it needs. |
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January 2003
Posts: 1498
Location: San Bernardino, California | 
Almost looks like traces 1 & 2 are shorted in the circled area. Make sure they are not. |
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October 2006
Posts: 7
Location: Austin, Texas | Good eye BruDeV! That connection was indeed bridged and I fixed it, unfortunately, the pre-amp still does not work. I guess that is why it was being bypassed. :( I'm sure it is fixable, it's just going to take some time to go through the board find the problem. oh well, back to the bench it goes. |
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December 2001
Posts: 7222
Location: The Great Pacific Northwest | I get questions all the time, about pre-amps that have no input signal. I've been lucky enough that most of the pre-amp issues I have had or had to fix were physical. Part missing, or broke. But I have a few that have the same symtom. You can hear the tone and notch filter change the "noise" on the output, but no input at all, pickups are fine. Is there a known weak point on the input before I go dig out my scope, signal generator, freq counter etc... |
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Joined:
February 2006
Posts: 76
Location: Fairfax, VA | Bacon: There are high-res schematics of the preamp in PDF on my site:
http://gewalker.googlepages.com/Ovation_Breadwinner_Schematic.pdf
They might help as well. |
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Joined:
October 2006
Posts: 7
Location: Austin, Texas | It's alive!!!
Many thanks to all of you for your help and advice. The problem was being caused by the switch inside the 1/4" jack, it was not making contact. I just unsoldered it pushed the contact out a bit and soldered it back on and voila, it was rockin' again.
Melmoth, thanks for the hig-res schematic images these will come in handy. Comparing the circuit on my board to the schematic, it seems that my board didn't exactly match the two drawings. I wonder if there is a 1251-0-350 E revision? Oh well, its working now. :)
Thanks again for the help..
Julio |
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Joined:
February 2006
Posts: 76
Location: Fairfax, VA | That looks like a rev-F board to me. Keep in mind that it can be tough to match up a schematic to a pcb at times. |
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January 2003
Posts: 1498
Location: San Bernardino, California | I've usually had problems with R10a, if it wears out it opens the signal path. An easy way to check is to short across it; the pre-amp will work, but the tone level compensation won't.
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Joined:
October 2006
Posts: 7
Location: Austin, Texas | Well, sure enough more problems have arisen. The guitar works great for a while. After about an hour or so, sometimes shorter, it starts to make a whole lot of noise and the pickups stop working. It will stay in this state until it is unplugged for a couple of minutes then plugged back in. Sometimes however, toggling the notch filter makes it come back. Does that sound farmiliar to anyone? Maybe its being caused by a dying capacitor?
That is an excellent schematic BruDeV. Thanks! |
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November 2003
Posts: 11039
Location: Earth·SolarSystem·LocalInterstellarCloud·Local Bub | Electric geek porn. Hands where we can see 'em fellers. |
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December 2003
Posts: 13987
Location: Upper Left USA | Careful, they're known for their resistance... |
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Posts: 14842
Location: NJ | "Ooooooh! . . you're a "Dirty Girl", aren't you?? . ."
-Robbie the Robot |
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October 2006
Posts: 7
Location: Austin, Texas | well, this thread took an weird turn.... |
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Posts: 11039
Location: Earth·SolarSystem·LocalInterstellarCloud·Local Bub | not taking a weird turn, would be a weird turn... |
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Posts: 14842
Location: NJ | ". . well, this thread took an weird turn . ."
How many newbies have typed THAT utterance? . . . |
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October 2006
Posts: 7
Location: Austin, Texas | Well, I think I found the cause of the weirnesses. After much tracing with a tone generator and an oscilloscope, I tracked the problem down to one of the JFETs - Q3. As it turns out finding a place that has these transistors in stock was just as difficult as finding a bad one in a circuit. I finally had to order some from Mouser electronics. Well, at least it will be fixed for good...(crosses fingers) |
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Breadwinner Electronics help...