Boss CE-1 Failure Vibrato

[Ilbauer69]

I have a Boss CE-1 from 1980.  It did work but I decided to recap it.  Yep you guessed it, now it has a problem.  The chorus still works fine.  The vibrato only works for about a second before the oscillation stops.  I still have sound.  When engaged it LED blinks rapidly before it goes dark.  If you adjust the rate it will blink faster before it goes dark. Hit the switch again to go back to chorus and it works just fine.

I did find a copy of the schematic.  Now I am new to this and although I can slowly read a schematic, transferring that information to the PCB is beyond me.  I can guess but I am not a fan of this.  The best copy of the schematics I could find is still difficult to read as it is a poor copy for the small print. I have been unsuccessful finding a component layout for the PCB board.

The only thing I can find about the vibrato on the schematic is that it is related to caps C34 & C35.  I do have a digital scope (not good at using it) and I can not get a signal from pin 7 of IC4.  I can when using chorus and it looks to be fine.  Just by guessing and process of elimination I found IC4.  I really need the PCB layout.  I believe I know where C34 & C35 are; again guessing.  Those caps are installed correctly (polar) and are the correct uf and voltage.

So any of you folks out there have any idea what could be wrong?  Like I said it did work but due to the age I wanted to recap it and put in the 500k pot as I use this for guitar. 

Thanks for your time.

[Ilbauer69]

Thought this might help is someone wanted to give me a location to look at.

[thermionix]

Here's a schematic in case that helps anyone.  Not sure it's the same version.



Any chance you put an electro in backwards?  Knock anything loose?

In the pic there are some screws missing.  In some older gear, they make grounds at the screw holes.  Don't know if that's the case with the CE-1 though.

[njkmonty]

from memory of my clone version  caps 34 and 35  are the top 2 on the top right  of the pcb with the wiring coming off, below the "Q and R"  maybe the negative sides of the caps have maybe had the pcb traces damaged?  check with continuity?

[njkmonty]

heres some links for pcb parts layout on board   scroll down on page

http://www.crazy-patroche.com/article-etude-du-chorus-boss-ce1-119548543.html

[Ilbauer69]

Thank you for the responses.  The schematic I have is the same that you provided.  From what I found it is the best quality out there.  And luckily it is the version I need.  The link to the other pictures are very useful.  One of those I had and I have been using.  I will be checking the others out here directly. To bad the layout one does not cross reference to the numbers on the schematic; example - C34 & C35.  It does show the values though and that will be nice to have.  I will say that I did only change one cap at a time and I took my time at that.  This is not the first vintage pedal I have worked on.  I am just not an electrical engineer. 

Thank you and I will keep this post updated.

[Ilbauer69]

With the use of the link with the images of the PCB with the components on it I believe I found it.  In C35 (following the trace) I have a .47 cap and it calls for a 4.7.  I did take pictures before and although I could not read that position I did have a sharpe mark on top of all the caps I was changing.  The mark on top of this cap was kind of unique so I was able to dig for the old one and see that it was 4.7.  Don't know how it happened.  I am really cautious.

Thanks for the help.

[Ilbauer69]

Oh just to reply back on that picture I made.  It was quick and dirty just to make something where components could be found.  I was not putting power to the pedal and if I recall correctly none of the screws are used for ground.  I do have all the screws.

[Ilbauer69]

Did have another question.  Apparently I do not have a polarized 4.7uf cap around today.  If I understand it correctly C35 is in the audio path.  If this is correct can I use a bi-polar cap in position C35?  I do have a new one of those.  Otherwise I will have to put in the old cap to see if this works.  The schematic does list a positive and negative side but I have heard of people replacing these with BP caps.  I did not know if it would be safe to do in this case.

[thermionix]

Yes, you can replace with bipolar, no problem.

[daz061]

heres some links for pcb parts layout on board   scroll down on page

http://www.crazy-patroche.com/article-etude-du-chorus-boss-ce1-119548543.html

are you going to make the CE-1 into a DIY project?

[Ilbauer69]

I have not ventured into the DIY pedal project yet.  Still learning how these circuits work.  Something like this is a little complex so I am still working on the old ones.  I was thinking about doing a hybrid of a tube screamer and EP-3 preamp at some point.

[Ilbauer69]

Yes changing that cap did resolve the issue for the vibrato not working.  HOWEVER I believe there still may be a problem.  There is a pretty substantial audio noise it is making that coincides with the effect;  it is a whooosh sound.  When I stop playing I believe this has some sort of internal noise canceling because there is a audio drop as well; until you start playing again.  This audio noise does not ever go away.

Any ideas, from experience, to know where to start looking?

Thank you....

[njkmonty]

does the woosh sound change when in hi or low setting?   and is it only in vibrato mode?

also did you accidentally  use wrong values for caps in other areas by mistake aswell?

[Ilbauer69]

No it was like this before the cap change.  I was hoping that changing the caps would fix this.  It happens on both Hight and Low input.  It does not matter what mode you are in.

[Ilbauer69]

Anyone have a copy of the service manual for the CE-1?  I was able to scope it and I am getting some pretty good noise on test point "E" from the schematic.  Did not know if the service manual would have any information on this.  Believe this might be the culprit for this pedal having noise in the output.  The noise is on "M" & "N" as well.  The other test points look pretty good.  Just a little low on the Vpp but not much.  Have not adjusted anything until I see if I have a bad active component.