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Paladin2019
Copper Member
United Kingdom
11 Posts |
 Posted - 10/19/2008 : 23:56:05
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Hello folks, new poster here looking for some expert advice!
My CE-2 currently uses the MN3207/MN3102 chip combination, but I keep hearing that the MN3007/MN3101 combo is more in demand and has superior tonal qualities. I've got these chips to hand, but people keep telling me that I can't just substitute one set for the other; something to do with the chips running at different voltages. What other changes do I need to make to the pedal before it will work with the MN3007/MN3101?
I'll probably be doing the Monte Allums mods as well - would this affect what I'm planing to do with the chips?
Thanks in advance for any advice. |
Edited by - Paladin2019 on 10/22/2008 01:43:52 |
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ChristoMephisto
Platinum Member
Canada
1288 Posts |
Posted - 10/20/2008 : 10:47:39
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Hi and welcome to the forum
The MN3007/3101 are the same, but not in production,
read a little history on the CE-2
http://www.analogman.com/clone.htm |
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Paladin2019
Copper Member
United Kingdom
11 Posts |
Posted - 10/20/2008 : 19:14:13
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So they are interchangeable as long as you use the matching set, that's fantastic news 
I'm going to socket them anyway and I've got some backup 3207/3102 chips in case of disaster.
One more question, would I benefit from twiddling the trimpot after the new chips are in or is it best left alone? |
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bossarea
Forum Admin
United Kingdom
3652 Posts |
Posted - 10/20/2008 : 20:14:01
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| If the characteristics of the MN3207 is a little bit different from the MN3007 you're putting in, you could be forced to do a bit of tweaking. Random tuning of the trimpots is however not recommended. The result could get much worse and you could have real trouble getting it to sound good. Going through the procedure in the schematic with a signal generator and a scope will get them set properly. |
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Paladin2019
Copper Member
United Kingdom
11 Posts |
Posted - 10/20/2008 : 22:43:57
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Unfortunately I have neither a signal generator nor a scope, nor do I know where I could find/borrow/buy/steal them. Hmm.... Anyone in the South Wales area reading this? 
One step at a time I think. I'll see how the new chipset sounds and worry about the adjustments if the results are not up to scratch. I'll definately be sticking to the socket idea though. |
Edited by - Paladin2019 on 10/20/2008 22:46:09 |
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Paladin2019
Copper Member
United Kingdom
11 Posts |
Posted - 10/22/2008 : 01:43:01
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Another quickie.
I found the schematic with descriptions of the adjustment procedure:
http://www.godiksennet.com/images/sch/CE2.jpg
Unfortunately the scan is poor quality and barely readable. It says to make the adjustment you must feed a signal into the input - 200Hz, +3[something].
I can work out everything else, but has anyone figured out what that [something] is? |
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Dr. Bob
Moderator
Australia
6593 Posts |
Posted - 10/22/2008 : 12:28:04
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Hi Paladin2019
The signal is about 100-200mV (millivolts) which is about the output level of an average single coil.
Else you will overload & distort the input stage signal.
Regards Dr. Bob
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nathanscribe
Silver Member
United Kingdom
376 Posts |
Posted - 10/22/2008 : 18:03:01
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quote:
Originally posted by Paladin2019
I can work out everything else, but has anyone figured out what that [something] is?
dbm? |
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Paladin2019
Copper Member
United Kingdom
11 Posts |
Posted - 10/22/2008 : 18:52:31
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DBM looks right and makes sense, thanks.
And thanks to Dr Bob too, this is all useful stuff to know  |
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bossarea
Forum Admin
United Kingdom
3652 Posts |
Posted - 10/22/2008 : 20:26:42
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I opened the schematic in an imaging program and messaged about with the image until the original text was readable.
Set controls as shown left
Feed a signal 200Hz, +3dBm,
sine into INPUT jack.
Connect an oscilloscope to
Q3 emitter.
Determine the BBD bias by
turning VR-3 to provide a
centered operating point
Not sure if it makes things any clearer |
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Paladin2019
Copper Member
United Kingdom
11 Posts |
Posted - 10/22/2008 : 21:16:35
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quote:
Originally posted by bossarea
Not sure if it makes things any clearer
You are a gentleman and a scholar :)
That's exactly what I needed, thank you! |
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nathanscribe
Silver Member
United Kingdom
376 Posts |
Posted - 10/24/2008 : 15:29:41
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| If you check the datasheets of the MN3007 and 3207, you'll notice they have different power supply requirements. I doubt you'd be able to simply do a drop-in replacement. |
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Dr. Bob
Moderator
Australia
6593 Posts |
Posted - 10/24/2008 : 16:54:23
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quote:
Originally posted by nathanscribe
If you check the datasheets of the MN3007 and 3207, you'll notice they have different power supply requirements. I doubt you'd be able to simply do a drop-in replacement.
Thanks nathanscribe
I was pretty sure that this was the case.
I was looking for my data sheets, but you beat me to it.
Good NOS - BBD's are a bit too expensive to trash.
Thanks again.
Regards Dr. Bob |
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Paladin2019
Copper Member
United Kingdom
11 Posts |
Posted - 10/24/2008 : 18:52:22
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quote:
Originally posted by nathanscribe
If you check the datasheets of the MN3007 and 3207, you'll notice they have different power supply requirements. I doubt you'd be able to simply do a drop-in replacement.
I've been told similar things to this before. What's really frustrating is that nobody has been able to tell me what actually needs to be changed to accomodate the 3007/3101! Monte Allums says he doesn't know, Analogman didn't know, I'm running out of pedal gurus to ask! 
(please note - this is not a rant at anyone here, just a general moan about something that I've got very little information on for 6 months)
I don't have a 3007 model CE2 to compare mine to, but I do have the schematic for it (see earlier post). I will go through the whole board and check component for component for any differences but if the changes are going to be in things like diodes then it's not going to be obvious what's been altered.
I cannot believe that there is so little information out there about the 3207 version of the CE2. I know they aren't supposed to be as good as the other ones but they are at least as common. I'll have to make some notes on mine, take some good pics and post my findings back here; maybe someone will find it useful in the future.
[Edited for language that amy have come across harsh] |
Edited by - Paladin2019 on 10/24/2008 19:09:05 |
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nathanscribe
Silver Member
United Kingdom
376 Posts |
Posted - 10/24/2008 : 19:13:04
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I only have the schematic for the 3007 CE-2, but I also have a schematic for the 3207 BF-2:
http://www.freeinfosociety.com/electronics/schemview.php?id=117
The quality's poor, but you can see the upper IC (the BBD) is connected to the power rails differently, and the driver IC clock is routed vice-versa to the BBD clock inputs. Also, the BBD outputs (pins 7&8) are tied to the other rail via the resistor.
I think that's it... my eyes are playing up today though.
As for PCB layout on your 3207 CE, you might have to bite the bullet and draw the circuit out. I've had to do this for a couple of things before... fun. |
Edited by - nathanscribe on 10/24/2008 19:16:11 |
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bossarea
Forum Admin
United Kingdom
3652 Posts |
Posted - 10/24/2008 : 19:18:49
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I haven't actually ever seen the 3207 version. Is it made in Taiwan or Japan? Serial number?
If you get some good pictures of the board I'm pretty sure we could put all our heads together and come up with a mod. |
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Topic |
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CE-2 chip query *UPDATE - SCHEMATIC*
