|
|
Joined:
December 2008
Posts: 11
Location: Enon, OH | Hey guys,
I need a tone pot for my white Breadwinner, the one I bought for $250 with 13th birthday money (plus my entire life savings) in 1993. The part number is 482004-C-97 and one section is definitely cutting out. I love my Ovations so much I now only own three guitars and Breadwinners are two of them. Please help a brother out...I'm new here and I'd greatly appreciate it. John Budny says he doesn't have any, by the way.
Crazy Joe |
|
| |
|
Joined:
April 2004
Posts: 13303
Location: Latitude 39.56819, Longitude -105.080066 | Send an email to Woody or Mr. Ovation. They are probably your best bet. |
|
| |
|
Joined:
December 2003
Posts: 13987
Location: Upper Left USA | Sorry for the blurry photos but I do have one - but it was removed from a CB for some reason.
You are welcome to it but I hope there is a good replacement part out there.
Welcome to the Parts Bin! |
|
| |
|
Joined:
December 2006
Posts: 6268
Location: Florida Central Gulf Coast | Gawd, I LOVE this place! 
It's as good as browsing through the ol' real deal Army/Navy Surplus Depot in Tampa as a kid ('bout 650 moons ago!).
BTW, welcome to the Ovation Relics (aka members) Knitting Circle! |
|
| |
|
Joined:
December 2008
Posts: 11
Location: Enon, OH | Hey Mr. Woody - any idea what the values are supposed to be? BOTH sections of mine are giving unstable measurement readings, and I've never had the correct schematic...in fact, I had to trace one out myself 'cause the one Nancy Heacox mailed me in eighth grade was for the wrong version! (I gotta quit these trips down memory lane.) BTW, what does CB stand for? Can't think of any solidbodies with those initials off the top of my head...
Crazy Joe |
|
| |
|
Joined:
January 2006
Posts: 1118
Location: NW Washington State | When was your Breadwinner made, and what revision of the board do you have? There are several lettered versions.
BruDev's schematic for the "D" version, he has other versions in the gallery (did he draw these? thanks to BruDev for providing them)
The "D" version from http://www.doremi.co.uk/breadwinner/
-Steve W. |
|
| |
|
Joined:
December 2003
Posts: 13987
Location: Upper Left USA | "CB" is Circuit Board to Plumbers like me! |
|
| |
|
Joined:
January 2006
Posts: 1118
Location: NW Washington State | I thought it meant Crappy Breadwinner. Non-plumbers might use PCB for Printed Circuit Board. |
|
| |
|
Joined:
December 2008
Posts: 11
Location: Enon, OH | Mine sez 400008-D...it has three transistors and a 1:4 step-up transformer, truly weird. Here's a schematic I traced out, omitting the pickup and battery switching circuitry for clarity as far as circuit design. Basically an input JFET source follower (buffer), an interstage step-up transformer, and two common-source gain stages with some equalization and gain-boosting stuff in the source circuitry. Strangely enough, they elected to put the volume control on the output, rather than buffer it between the stages. Not how I would have designed it..but come on, the thing sounds so good even I won't mess with it. My guess is that it's the same tone pot value, since the surrounding circuitry is the same.
www.crazyjoe.org/eBay4/400008-D.tif |
|
| |
|
Joined:
January 2006
Posts: 1118
Location: NW Washington State | Joe-
Nice job on the schematic. Separating the sections from the pickup switch helps clear things up.
BruDev has an "E" version with the interstage transformer here: http://www.ovationfanclub.com/photos/BruDev_63183_e.jpg
The Breadwinner fanpage also has an "E": http://www.doremi.co.uk/breadwinner/diag3.jpg
These might be similar to yours, I don't understand the meaning (if any) of the letters.
I wonder if higher input impedance would be an improvement? Maybe move the notch filter in front of the second FET too. Reduce the depth of the notch a bit. Tone down that wacky out-of-phase sound. And design a whole new preamp while you're at it. :)
-Steve W. |
|
| |
|
Joined:
April 2006
Posts: 2491
Location: Copenhagen Denmark | FAULTY CAPACITORS !!
Exchange the caps. and it will work again , exchange them all !!
( ye`r in luck the values are given )
Such low values cost only dollars and cents...
Vic
..further explanation of why , will be given free of charge.. |
|
| |
|
Joined:
January 2006
Posts: 1118
Location: NW Washington State | . |
|
| |
|
Joined:
April 2006
Posts: 2491
Location: Copenhagen Denmark | Originally posted by numbfingers:
. Est tu Numby ...
Allright then , :
The schematic contains , pots. , coils , transformer , resistors , and...Capacitors !!
Pots. can crackle , but the gent mentions the system .. " cutting out " .., Coils do not wear , neither do transformers , resistors loose their .. " resistance " .. over time , but not likely in this case .. ( however exchanging those would not be a bad idea ) .. , transistors are electro-chemical switches , either they work or they do n`t , in which case , the appliance does not work , Caps. however...they Dry Out !!..and cause , .." intermittant " probs. , so , 10 to 1 , the fault is with those caps.
..or a loose connection.. cable break..( doubtful )
..not easy to try to fix by remote control..
Note to Iffy :
No need to kick my cute little round behind , Numby has taken care of that allready.. :)
Vic |
|
| |
|
Joined:
December 2006
Posts: 6268
Location: Florida Central Gulf Coast | Originally posted by HumblePie aka Solid Top:
Note to Iffy :
No need to kick my cute little round behind , Numby has taken care of that allready.. :) Vic, no good deed goes unpunished. Besides, I hate standing in lines!  |
|
| |
|
Joined:
January 2006
Posts: 1118
Location: NW Washington State | Gee, all I did was bite my tongue and edit my post down to a "."
Looking at Joe's initial post and the schematic he drew, I realized that he probably doesn't need a lot of advice, just the tone pot that Woody has.
-Steve W. |
|
| |
|
Joined:
December 2008
Posts: 11
Location: Enon, OH | Hey Steve -
Since you've opened up the can of worms on mods... ;)
The main thing I did to my guitar was flip the phase of one of the pickups. Well, in the dual-pickup switch position, there's an enormous gain boost to compensate for the out-of-phase drop...so you have to pull that 100k resistor that shunts the second transistor's source terminal. When my tone pot started losing a section and no amount of spray cleaning could save it, I did do an experimental modification and jumpered from the transformer right to the volume control; bypassing two stages, the tone pot, and the notch filter. VERY clean and transparent, the pickups still buffered from cable capacitance, and with them in-phase it was hi-fi almost like Chet or Les (and I did once champion the Les Paul Recording!). I've had it like that for about a year now, but I miss some of the edge or punch or something it had originally. I did another, much scarier mod that I'll tell you about if you want to hear it...
By the way, and I certainly don't mean to be a know-it-all, but there are no chemical electrolytic capacitors anywhere near the tone control and besides, I've found that with the low voltages and temperatures in the guitars (EXCEPT WHEN I'M SHREDDING RED-HOT LIXXX, THAT IS :D ), even 40-year-old caps test and work just fine. |
|
| |
|
Joined:
January 2006
Posts: 1118
Location: NW Washington State | Joe-
I agree on the caps, they're probably OK. I have thought about replacing the electrolytic that's in the signal path just before the volume control with a film cap, if one would fit. Seems like something a hi-fi guy would do.
I adjust the pot for the out-of-phase position so that one pickup predominates. The null setting that the manual suggests isn't my favorite.
When I got my Deacon in the 70s, one of the first things I did was to shield the interstage transformer. It was picking up some hum. Luckily I didn't modify the board any further, I probably would have trashed it. Since the original boards are rare and fragile, I think it's best to roll your own if you want something different. As you say, nothing else sounds the same. I'm not always sure that it's a good sound, but it's the original sound.
-Steve W. |
|
| |
|
Joined:
December 2003
Posts: 13987
Location: Upper Left USA | God bless the electrical Engineers! We are lost without you and we we will never understand you. But without us, you would all perish.
Just keep doing what you do and the rest of us will feed you, tell you how to dress and benefit from your efforts.
Keep in mind that the parts used were commonly stocked Military Aircraft technology from the 70's so don't feel bad if some of it can only be found in museums and swap Meets. |
|
| |
|
Joined:
January 2006
Posts: 1118
Location: NW Washington State | Maybe Joe and Vic are EEs. I'm not, I'm just an amateur geek.
Joe, if you do get that pot from Woody, you should test it carefully. I think he uses a propane torch to remove parts from the PC board. :)
-Steve W. |
|
| |
|
Joined:
December 2003
Posts: 13987
Location: Upper Left USA | I now have more articulate toolage in my arsensal thank you very much! I keep the tiny pencil tip solder-er next to the 45 watt gun...
... the Brazing Torch is in the garage for back up though! |
|
| |
|
Joined:
December 2008
Posts: 11
Location: Enon, OH | Woody - you are most certainly correct, sir...if left to my own devices, I would be found in a field, emaciated and wearing mis-matched polyester. And not the kind that can be used for capacitor dielectrics. And not a magnetic or electric field. |
|
| |
|
Joined:
December 2003
Posts: 13987
Location: Upper Left USA | On Gilligan's Island the best Tool in the Toolbox was the Professor - he could keep your OP Pro running with a couple of Lemons and some wire!
You guys just amaze me, I was blinded by science! |
|
| |
|
Joined:
December 2008
Posts: 11
Location: Enon, OH | Hey Woody -- got the tone pot, THANK YOU!!! I'll be installing this baby today or tomorrow and I'll certainly keep you informed. I can't wait to get the ol' boy back and running.
Joe |
|
| |
|
Joined:
December 2008
Posts: 11
Location: Enon, OH | Woody - I got bad news (for me, anyway)...your tone pot had the same problem as mine; for whatever reason, the front section's carbon track just disintegrated. I wonder if that was a recurring problem. Anyway, thanks a million for sending it to me. Anyone else out there have any thoughts?
Joe |
|
| |
|
Joined:
December 2001
Posts: 7222
Location: The Great Pacific Northwest | Joe,
Send me an email to mileskb at aol.com I may have one in good shape. Email is the best way to insure I go look. |
|
| |
|
Joined:
August 2004
Posts: 604
Location: Tampa, FL | Joe,
You might try emailing BruDev. He helped me out (Twice) when I was trying to help a fellow OFC'er.
Somethings to consider:
I don't think the stacked pots are identical either in value or taper. seems to me one was 2X the value of the other and one was linear and the other was logarithmic.
I can say that the carbon flaking off the substrate is what I found to be the problem with the Tone pot I was messing with. It seems to be a recurring mode of failure. |
|
| |
|
Joined:
January 2003
Posts: 1498
Location: San Bernardino, California | I think what happens is that the sponge rubber in the battery compartment decomposes and gets into the pot.
Lift the 4 tabs on the top edges. Remove the threaded piece and the top wafer. Do the same with a 500K linear CTS pot. Put the 500k wafer on the tone pot. Put the threaded piece back on. Bend the tabs back down.
The treble/bass won't be the same but, it's real close. You can try different values for the treble bypass if you want.
Or replace the gate resister on the following stage with a trimmer. (750K?) And use that to dial in the treble/bass balance. |
|
| |
|
Joined:
January 2003
Posts: 1498
Location: San Bernardino, California | PS You'll need to lengthen the leads on the 500K wafer. |
|
| |
|
Joined:
December 2008
Posts: 11
Location: Enon, OH | Hey BruDev - I didn't even see your posts until recently, I'm apparently not smart enough to go to the second page! I ended up doing exactly what you describe, except that I used a 500k audio-taper wafer (because I had one). It worked great and the sweep is actually pretty darn close to the original. Thanks for the advice! This place is great, I'm so glad there's a whole slew of you guys who love these guitars. By the way, SUPER nice job on the schematics, totally cleared up what the tone pot values are supposed to be.
Kind regards,
Crazy Joe |
|
| |
|
Joined:
January 2003
Posts: 1498
Location: San Bernardino, California | Great.
I suspect that you could use a 1 Meg pot and put a parallel resister across it, and get even closer.
I've seen a few other variations of the preamps, but the changes are so minor that I didn't put in the effort of pulling the circuit boards from the guitar to draw a schematic. |
|
| |
|
Joined:
December 2003
Posts: 13987
Location: Upper Left USA | I am resurfacing this post for two reasons:
A) Andrew in Oz asked about a Breadweiner schematic
B) You Electronical people are awesome! |
|
| |
|
Joined:
January 2006
Posts: 1118
Location: NW Washington State | I think that BruDev is The Expert on this stuff.
Andrew in Oz sent me an email and I replied with the usual info...
Here's a link to a page that explains how the preamp works: http://www.ovationtribute.com/Catalogues/Breadwinner%20Settings%20M...
It's not worthwhile for the average person to try to make an exact copy of the original preamps. They used some custom-made parts that aren't available anywhere I've looked. But here are some schematics from OFC member BruDev:
http://www.ovationfanclub.com/photos/BruDev_63029_c-2.jpg
http://www.ovationfanclub.com/photos/BruDev_63084_c-3.jpg
http://www.ovationfanclub.com/photos/BruDev_63139_d.jpg
http://www.ovationfanclub.com/photos/BruDev_63183_e.jpg
http://www.ovationfanclub.com/photos/BruDev_63233_f.jpg
The last two schematics on this page are for Breadwinners: http://www.doremi.co.uk/breadwinner/circuits.html
The second one from the top is for a UKII and was posted on the Breadwinner page by mistake.
If you want to duplicate the action of the Breadwinner preamp, you need an active bass/treble "tilt" control on a single knob, a volume boost ganged to the pickup switch when both pickups are selected in parallel and out of phase, and a midrange notch filter switch with volume boost. I can imagine several ways to get close to this but don't have any specific suggestions. It would be pretty easy to build a preamp with conventional volume and tone controls and maybe a treble boost in place of the notch filter switch. Or you could try one of the Artec preamps that are commonly available on eBay.
-Steve W. |
|
| |
Breadwinner tone pot - please help a brother out!