CE-2 troubleshooting

[Daxen]

Hi

I have an old Boss CE-2 that stopped working. The pedal powers on and the LED light up. It passes clean signal and when it's on it gets a little louder, but no chorus effect. Turning the rate knob does nothing, but when I turn the depth knob there's some modulation effect while turning.
I have measured the different voltages on the components as per the FAQ.

IC1

4.97
8.70
4.97
4.97
4.97
4.97
0
4.96

IC2
Around 8 and drops to zero
8.69
0.06
0.66
4.00
4.00
0
0.65

IC3
0
0.58
4.47
4.21
3.66
4.50
3.66
8.73

IC4
8.73
0.58
4.47
2.49
0
7.97
4.49
0.24

Q1
3.82
8.77
3.13

Q2
4.19
8.72
4.26

Q3
3.95
8.76
3.44

Q4
0.12
8.70
0.53

Q5
0
7.69
0.32

Q6
0
0.01
0.6

Q7
0
0.01
0

Q8
0
0.07
0.60

Q9
4.99
0
5.00

Any help in troubleshooting what is wrong and get this old pedal working again? Help much appreciated =)

[Daxen]

I know it's not a DIY pedal, but I would appreciate it very much if anyone would help =)
Feel free to correct me if I need to provide more info or a soundclip to make it easier to troubleshoot.

[bluebunny]

The first two opamp chips (assuming you're following the BOSS schematic) look off.  How are you counting the pins?  Should be like this, depending on whether yours have a dot or a divot:
  _____         _____
1|o    |8     1|  U  |8
2|     |7     2|     |7
3|     |6     3|     |6
4|_____|5     4|_____|5

[Daxen]

I use this: https://www.electrosmash.com/images/tech/ce-2/boss-ce2-layout.png

I can see I count them wrong. I just googled IC pinout.
The right voltages for the pinout you provided is.

IC1

1: 3.99
2: 3.99
3: 3.97
4: 0
5: 3.93
6: 3.99
7: 3.99
8: 8.76

IC2
1: 0.67
2: 0.06
3: 4.68
4: 0
5: Around 8 and slowly drops to 0
6: 4.01
7: 0.66
8: 8.75

IC3
1: 8.68
2: 4.47
3: 3.22
4: 0.57
5: 0
6: 4.44
7: 2.50
8: 2.50

IC4
1: 8.68
2: 4.44
3: 0
4: 4.47
5: 0.24
6: 7.91
7: 2.47
8: 0.57

[bluebunny]

Here's a matching schematic:



It's the one I have in my stash and corresponds with the layout you posted.

From your description of what happens when you twiddle the depth control, perhaps the LFO (IC2) isn't oscillating?  You'd expect the output (pin 1) to change according to the speed setting.  This then modulates the clock (IC4), which drives the BBD (IC3).

Someone with more in-depth knowledge of BBDs will be along shortly to contribute some more. 

[Govmnt_Lacky]

From your description of what happens when you twiddle the depth control, perhaps the LFO (IC2) isn't oscillating?  You'd expect the output (pin 1) to change according to the speed setting.  This then modulates the clock (IC4), which drives the BBD (IC3).

Agreed! Looks like your problem is with the LFO circuit (IC2). Maybe take a look at the Rate pot to make sure it is connected/wired well (no cold solders, loose joints, or broken wire connections) and then look at the components around IC2 listed in the schematic. If all of that looks good, try replacing IC2.

Good Luck!

[Daxen]

Thank you so much for the help. Upon further investigation now you told me where to look, I seems like that the rate pot is dead.

[Daxen]

Didn't have a new pot, so tried taking the one in it apart and could see that the wiper didn't have very good contact with the carbon. Bent the wipers up a bit, so they would have better contact and assembled the pot again. Now everything is working fine. Thank you very much for steering me in the right direction =)

[ElectricDruid]

Welcome Daxen, and good work!

Isn't it nice when something starts working?!?

[Fender3D]

...taking the one in it apart and could see that the wiper didn't have very good contact with the carbon. Bent the wipers up a bit, so they would have better contact and assembled the pot again. Now everything is working fine.

You're spoiling the old repairmen's pots secret! Hush, hush, or their guild will kill you... 

[PRR]

> Hush, hush, or their guild will kill you...

They don't do that any more. They just turn you down to zero.