Tonepad CE-2

[guitar413]

I just put together a tonepad CE-2, when I switch pedal on it seems to have no effect, turning trim pot has no effect, replaced MN3007 and trim pot... no change. any suggestions?

[Kipper4]

Welcome to the forum.
Some really useful info here
http://www.diystompboxes.com/smfforum/index.php?topic=29816.0

[guitar413]

I checked voltages, with trim pot at 12 o'clock and rate and depth at max
IC1 (4558)
1) 4.53     8.95
2) 4.53    7) 4.53
3) 4.53    6) 4.53
4) 0.0      5) 4.53

IC2 (TL072) - used this as a replacement for the TL022
1) 8.25   8.95
2) 2.95   7) 1.35
3) 4.19   6) 7.51
4) 0.0     5) 2.95

IC3 (MN3007)
1) 7.69     3.46
2) 3.92     7) 3.46
3) 3.04     6) 4.39
4) 0.0      5) 0.0

IC4 (MN3101)
1) 7.69   6.88
2) 4.39   7) 2.12
3) 0.0    6) 6.84
4) 3.92   5) 0.34

Q1
E) 3.65
B) 4.06
C) 8.95

Q2
E) 3.86
B) 4.35
C) 8.95

Q3
E) 3.72
B) 4.15
C) 8.95

Q4
E) 0.78
B) 1.29
C) 7.69

Q5
E) 0.0
B) 0.41
C) 6.42

[guitar413]

I can post photos of board if that will help too.

[Mark Hammer]

1) Having built one from the Tonepad layout, I can vouch that there is nothing at all wrong with the layout itself.

2) I always recommend cleaning the excess flux off of boards that haven't been fully debugged.  It's useful to be able to see each and every trace and solder joint clearly, without them being obscured/masked by blobs of flux.

3) Are you confident the 3007 and 3101 were obtained from a reputable and dependable source?

4)  If the answer to #3 is yes, and there don't appear to be any cracks or bad solder joints, verify, with your meter, that there is actually a waveform coming out of the LFO, and that there is actually audio signal at the input to the BBD.

[guitar413]

Thanks I'll give that a try....I got the MN3007 and 3101 from Smallbear.

[guitar413]

1) Having built one from the Tonepad layout, I can vouch that there is nothing at all wrong with the layout itself.

2) I always recommend cleaning the excess flux off of boards that haven't been fully debugged.  It's useful to be able to see each and every trace and solder joint clearly, without them being obscured/masked by blobs of flux.

3) Are you confident the 3007 and 3101 were obtained from a reputable and dependable source?

4)  If the answer to #3 is yes, and there don't appear to be any cracks or bad solder joints, verify, with your meter, that there is actually a waveform coming out of the LFO, and that there is actually audio signal at the input to the BBD.

thanks I'll give that a try...I got the MN3007 and 3101 from smallbear.

[guitar413]

I didn't make this the board, I bought it from Smallbear and it has a white solder mask on it. I did not check the traces with a meter before populating it. If I can't track down the problem Iam going to make my own board.

[Mark Hammer]

If you got the parts from Small Bear, then you can trust them.  I think the last 3007 chips I bought were sitting in a parts drawer, and handed to me over the counter without any sign of anti-static protection whatsoever.  Honest retailer, mind you, but they didn't know those chips were somewhat static sensitive.  So, it can happen that people sell chips, in good faith, that are in less than usable form.  Small Bear has a very targetted market, and takes steps to assure that the specific items that market wants are up to spec.

If the board and key components are AOK, and the trimpot seems to have no impact, then the next things to consider are that none of the chips are inserted backwards.  The posted voltages suggests they are in just fine, although I would recommend swapping the TL072 for something closer in current-consumption to the TL022, such as an LM358.  The TL072 tends to draw enough current that when it generates the initial square wave (that is converted into a triangle), it produces a spike on the power lines that you'll hear as a "tick" at the oscillation rate,...once you get it running.  The circuit WILL work okay with a 72; you'll just find the tick annoying.  So get a TL022 or LM358 when you can.

As noted, even if the audio path isn't presently working, you can still verify that the LFO is doing what it should.  Set the rate control for slowest, and measure the DC voltage on pin 7 of IC2.  If the LFO is working, it should get higher and lower.

[Govmnt_Lacky]

...although I would recommend swapping the TL072 for something closer in current-consumption to the TL022, such as an LM358.  The TL072 tends to draw enough current that when it generates the initial square wave (that is converted into a triangle), it produces a spike on the power lines that you'll hear as a "tick" at the oscillation rate,...once you get it running.  The circuit WILL work okay with a 72; you'll just find the tick annoying.  So get a TL022 or LM358 when you can.

+1

TL072 is NOT an acceptable substitute for the TL022 when being used for an LFO. You need a low current dual op amp here. Follow what Mark suggest and use either the TL022, TL062, or...my favorite.... the LM358 here.

Also, I will need to disagree with Mark concerning the "The circuit WILL work okay with a 72." Certain LFO circuit just will not modulate without a low current op amp in the circuit. I believe the CE-2 is one of them.

[Mark Hammer]

I may well stand corrected, then.

And in the interests of getting the OP's pedal off the ground without having to order in anything new, would simply swapping the 4558 and TL072, such that the 4558 is handling the LFO chores, and the TL072 the audio path, temporarily provide a functioning (but ticking) LFO?  That is, does the difference in current consumption between the two make a (temporarily) acceptable LFO?

[Fender3D]

Strangely enough you got 6.88V on IC4's pin 8 and 0V on IC3's pin 4...
All dedicated pins are equal before the Vgg  :

Also check clock pins out, since their voltages are different...

[Govmnt_Lacky]

To be honest.. I have never had a "ticking" LFO. I have had LFOs that either worked OR they didn't warble.

To the OP...

Try other dual op amps with similar pinouts and see if you can get it going. (4558, 5532, 082, 062, whatever you have on hand)

Your best bet will be either a TL022, TL062, or the LM358 though 

[Kipper4]

maybe a 1458 too?

[guitar413]

If you got the parts from Small Bear, then you can trust them.  I think the last 3007 chips I bought were sitting in a parts drawer, and handed to me over the counter without any sign of anti-static protection whatsoever.  Honest retailer, mind you, but they didn't know those chips were somewhat static sensitive.  So, it can happen that people sell chips, in good faith, that are in less than usable form.  Small Bear has a very targetted market, and takes steps to assure that the specific items that market wants are up to spec.

If the board and key components are AOK, and the trimpot seems to have no impact, then the next things to consider are that none of the chips are inserted backwards.  The posted voltages suggests they are in just fine, although I would recommend swapping the TL072 for something closer in current-consumption to the TL022, such as an LM358.  The TL072 tends to draw enough current that when it generates the initial square wave (that is converted into a triangle), it produces a spike on the power lines that you'll hear as a "tick" at the oscillation rate,...once you get it running.  The circuit WILL work okay with a 72; you'll just find the tick annoying.  So get a TL022 or LM358 when you can.

As noted, even if the audio path isn't presently working, you can still verify that the LFO is doing what it should.  Set the rate control for slowest, and measure the DC voltage on pin 7 of IC2.  If the LFO is working, it should get higher and lower.

Thanks

[guitar413]

...although I would recommend swapping the TL072 for something closer in current-consumption to the TL022, such as an LM358.  The TL072 tends to draw enough current that when it generates the initial square wave (that is converted into a triangle), it produces a spike on the power lines that you'll hear as a "tick" at the oscillation rate,...once you get it running.  The circuit WILL work okay with a 72; you'll just find the tick annoying.  So get a TL022 or LM358 when you can.

+1

TL072 is NOT an acceptable substitute for the TL022 when being used for an LFO. You need a low current dual op amp here. Follow what Mark suggest and use either the TL022, TL062, or...my favorite.... the LM358 here.

Also, I will need to disagree with Mark concerning the "The circuit WILL work okay with a 72." Certain LFO circuit just will not modulate without a low current op amp in the circuit. I believe the CE-2 is one of them.

I ordered some 022's the other day and will swap it when I get them....Thanks. all you guys are awesome to get advise from...wish I had the knowledge you do...but I guess I do when I can rely on you and get your advise...Thanks again.