boss ce-2 ... where is R-21, the vibrato mod? mark hammer?

[tele_guitarist]

Can't find it!! My circuit board isn't labeled, can anyone give me some help? I have this bit of info from Mark Hammer posted on here:

R-21-----  Vibrato by inserting a SPST toggle on either side of R21 to lift the dry signal.disconnect one end of R21, and let it float: so the dry signal doesn`t get added/mixed with the wet one.

thnks!!

[Fret Wire]

This has been floating around the net for awhile, slightly hard to read. I tried photo enhancing mine, not much improvement. R21 is 47k. Redhouse, we're already using your new site to help DIY'ers.

http://www.godiksennet.com/images/sch/CE2.jpg

[tele_guitarist]

thanks much!!

Any idea how I can increase the depth?

:?:

[Mark Hammer]

The parts layout shown helps a bit, but not in an explicit way.  The one you want is someowhere tot he right of IC1, but there are several 47k resistors there as you can see.  Find the one bridging pin 2 and 7 of IC1.  That's your target.

"Increase the depth" has several meanings.  It could mean the intensity of the effect, or it could also mean how big a change in delay time is produced by the LFO/clock.  The former would more properly be called "effect intensity" and the latter would be more properly called "sweep width".

The LFO circuit does not appear to have any component restricting the amplitude of the the LFO and hence the sweep width, although I suppose there might be something in that little jungle of parts between the DEPTH pot and the MN3101 that determines how LFO voltage changes translate into clock rate changes.  I don't pretend to understand that part.  I only know that it happens.

In general, the apparent width of sweep will depend on the delay range and the LFO rate.  At longer delay times, and at faster speeds, the same sweep width seems greater (which is why most choruses have a depth/width control, to tame the sweep so it sounds better at higher speeds).  Of course, when the dry signal is cancelled/lifted/disabled, and all you have is the delay signal, the apparent sweep width ("wobble") is even greater.

For modulated effects that use a wet/dry mix to achieve comb filtering through cancellations, like choruses, phasers, flangers, etc., maximum effect intensity is often a function of achieveing a perfect 50/50 balance between wet and dry.  It *CAN* happen that the tolerances of the usual 5% resistors used in commercial products result in a less than perfect 50/50 mix, but it won't be all that far off, even when not dead on.  Still, it is within the realm of possibilities that a trimpot on the board could be used to achieve a more precise balance.  Bear in mind that this will simply make the notches created as deep as they can be, but will not change the apparent "thickness" of the effect.  For that you may have to bump the delay range over a bit.

Which brings us to a delay-range mod.  There will be a 47pf capacitor right beside the MN3101.  This sets the overall range of delays produced.  If you wish to move more towards the "Pat Metheny" end of chorus sounds, try adding in a 10-22pf cap inparallel with that one.  A small ceramic cap should be able to be tacked on to the same pads as the 47pf cap on the copper side of the board without preventing lid closure.  Try some paralle caps with the guitar plugged in and see if you like it.  If not, the cap can be removed and the unit left stock.  If you find the delay-range shift is more to your liking, then consider removing the original 47pf cap and replacing it with a higher value one (e.g., 56pf, 68pf) of the same type.

Note that increasing the delay range will also, as hinted at earlier, make the amount of "wobble" and pitch detuning even greater.  If you do the vibrato mod, you may find there are few occasions where you set your "depth" control above halfway.

[tele_guitarist]

As always, Mark, you are very helpful, and most appreciated!!

[Pastrychase]

Did you ever find it then Tele? I'm attempting this mod, but I still can't figure it out which one it is, but then I never was the sharpest tool in the box.

[Mark Hammer]

No problem.  It's not like hammers have a finely honed edge either! :lol:

The service diagram for the PCB numbered 052-516B indicates that if you are looking at the component side of the board, with the connecting wires on the "north side" of the board, on the "northeast" corner, there will be a dual op-amp labelled uPC4558.  The resistor in question joins pins 7 (output of the first op-amp stage - IC1a) and 2 (input pin of the mixing stage - IC1b).

So here's what you have to do.  Note where any nearby 47k (yellow, purple, orange) resistors are.  Flip the board over and figure out which of the pads on the copper side are the pads for pins 2 and 7.  Now follow any traces connected to those pads "backwards" until you hit two adjacent pads that *might* be for a vertically-mounted resistor.  Quick.  Flip the board over and check whether there is a 47k resistor in that very spot.  There will only be ONE component linking those two IC pins, so if you find a 47k resistor, you've hit paydirt.

Now, how to enable the mod....

First, you need to decide if you want to be able to hit the bypass switch and revert to clean sound, or whether you are happy to have to flick the toggle back to chorus to be able to use the bypass switch.  The second one is easier to implement than the first.  If you would like the first, there is a thread concerning how to use the unused portion of the flip-flop to enable FET switching even when you've cancelled the dry signal.  Sounds to me like it's a bit outside the perimeter of your chops at the moment, so we'll leave it for later.

To do the second one, you can simply unsolder the resistor, and stick two wire leads in the same pads.  One of the leads goes to one lug and the other lead goes to 47k resistor and THEN to the remaining lug of a SPST switch.  It's a good idea to slide a piece of heat shrink over the second wire before soldering the resistor.  Once the resistor is soldered in place, slip the heat shrink over it and warm/shrink it for rigiidity and strain relief.

That's it.  Instant wiggly-tone.

[Joe Kramer]

Hi!

If you're still looking to do this mod, something in this thread may help:

http://www.diystompboxes.com/sboxforum/viewtopic.php?t=31668

Good luck!

Joe

[Pastrychase]

Ah, it seems to make sense now, thanks to the explanation. I'll give it a go and see if I can find it. If I succeed I'll post a pic of the CE2 guts showing exactly which resistor it is for other simpletons like me. I can't promise anything though.

[Pastrychase]

It's the one with the ring around it, top-right-ish. If anyone needs pics of where IC1 pin2 or Q6 collector is then just say and I'll furnish you with pics.

I know inexperienced types like me aren't very popoluar round here at the moment, but I though I may as well try to give something back.

[Joe Kramer]

It's the one with the ring around it, top-right-ish. If anyone needs pics of where IC1 pin2 or Q6 collector is then just say and I'll furnish you with pics.

Good work PC!  I haven't got around to doing this mod myself yet, and your detective work helps me a lot.  Thanks!

 

I know inexperienced types like me aren't very popoluar round here at the moment, . . .  

NONSENSE!  A wise man once said, "Experience is the mother of Illusion." Besides, we all start out inexperienced.  One of the joys of DIY is discovery, the adventure of learning.  If experience entails license for pride or arrogance, I want to be a beginner forever.  Within the DIY community there should never be a fixed hieracrchy, which fosters enmity between high and low, but only respect for and interest in knowledge and good workmanship.  The only real enemies of DIY are the forces of commerce and profit motive, which sacrifice quality and fruitful labor to greed and convenience.  Amen.

Fly your beginner flag high, and keep up the good work!

Regards,
Joe

[Fret Wire]

I know inexperienced types like me aren't very popoluar round here at the moment, but I though I may as well try to give something back.

Not with most people here. Helping the newcomers is what keeps everything fresh and interesting. Whether you help directly or not you get debugging experience with not only a specific ckt, but also your general debugging skills stay sharp. It's like owning 1000 pedals without the cost. I always felt that newcomers posting for a little help getting their pedals fired up is what keeps the whole point of this forum stay in focus. Then, those who haved been helped, turn around and help others. Can't get any better than that.

[Pastrychase]

Well, after those kind and encouraging words I may as well post what I used and found out to do this mod:

It started from what was written and discussed in this thread
http://diystompboxes.com/sboxforum/viewtopic.php?t=31668&highlight=ce2


Which was then written up by vanhansen on his website with some instructions and a circuit diagram
http://home.earthlink.net/~ehansen3/diy/ce2.htm

So using this as a guide I got hold of the components. I went for the J113 switching FET as it was the only one of the two suggested I could find available to me in the UK. I ordered this, and the rest of the ingredients (bar the stripboard and switch) from http://www.cricklewoodelectronics.com

Thanks to the help from Mark Hammer in this thread and the CE2 schematics floating around

http://www.depoprovera.co.uk/forums/avatars/BossCE-2.gif
http://www.depoprovera.co.uk/forums/avatars/CE2.jpg

I found the position of R21 (see above) and the other necessary components




After that it was just a case of assembling the small mod circuit on a board (I can post diagrams of this as well if anyone wants), wiring it in and drilling the hole for the switch. As a side note, I didn't solder the ground directly to the back of the circuit board as indicated, if you follow it round it goes up to wire 12, which runs to the back of a jack socket, so I soldered onto the tag there.

The datasheets that I found for the J113, 2SC945P (Q6), and the 1N914 diode are here, which I used to figure out which pin belonged where.

http://www.depoprovera.co.uk/forums/avatars/2sc945.pdf
http://www.depoprovera.co.uk/forums/avatars/85622.pdf
http://www.depoprovera.co.uk/forums/avatars/J113.pdf

And it worked a treat. This is the first time I've done a mod, so I was was quite surprised when it actually worked. If anyone has any further questions then I'll try my best to answer, but like I say I'm no expert. Please feel free to tell me I've made mistakes and that my house will burn down if I continue to use this pedal.

PS. The images and pdfs are all on my own hosting. I know someone else here posted the pics of the CE-2 guts I used, so if you want to lay claim to them then be my guest, I just can't remember who you are. But thankyou. Similarly if anyone thinks I shouldn't be hosting the pdfs then say and I'll take them down. They were, however, freely available on the manufacturer's websites. And as I'm sure is common round here, I take no responsibility if this completely ruins you pedal.

PPS. A big thanks to everyone who's helped.

[vanhansen]

I'm glad to see you it to work, Pastrychase. And glad to see my instructions helped out.  It's always good to know that stuff you put out there to help others is being used.  My phase 90 page is hit very often and usually a top return in google searches for phase 90 mods.

[sodapop]

How about R-21 on CE-2B?  My circuit board has all the numbers on it,  except I cannot find R-21 anywhere.  Is this because there is no R-21 or it is named something else?  The Resistor circled a few posts up on my board looks to me like it is R-8?  I noticed there are a couple other differences between CE-2 and CE-2B.  If any one has any info that would be great.  I would like to do these mods as well.  Does anyone have a side by side comparison of the 2 boards? I had a post up somewhere else,  but it must have been to vague or in the wrong spot or something.

[vanhansen]

Just so sodapop's questions aren't left hanging open here, it looks like we got them answered.

http://www.diystompboxes.com/smfforum/index.php?topic=40393.0

[sodapop]

Just so sodapop's questions aren't left hanging open here, it looks like we got them answered.

Sort of, I think,  maybe?

Thanks very much!!!