Tonepad CE-2 Chorrral Chorus (WEAK VOLUME and muddy?)

Started by sevenisthenumber, September 25, 2009, 07:12:54 PM

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sevenisthenumber

I built this up on PCB and have triple checked for:
1) bridged joints
2) correct values
3) tried different 4558 and tl022.. dont have extra of the other chips.
4) broken traces

I get the chorus and the depth, speed, vibrato switch and depth switch work fine. THe problem is, the volume is about 10db lower than bypass and its super muddy?

ANy help is MUCH appreciated.

anchovie

Audio probe time. Sounds like there's a point on the board that is forming a low-pass filter when it shouldn't be, if you can get the highs back you may well see the volume increase with it.
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sevenisthenumber

So starting at the input, just trail along till I hear highs? I REAAALLLY studied the pad side and it looks perfect...?

anchovie

You should hear highs at the input (if not, you've found the problem straight away!). Trace until you find the point where it goes muddy.

Even if the soldering looks perfect the circuit isn't performing correctly, so as it's an audio circuit the best way to debug is with your ears!
Bringing you yesterday's technology tomorrow.

sevenisthenumber

here are my voltages:

mn3101
1) 9.6
2) 0
3) 0
4) 9.6
5) .9
6) .9
7) 9.6
8)0

mn3007
1) 9.6
2) 0
3) 6.5
4) .9
5) 7.4
6) 7.4
7) 9.6
8) 0

i have replaced everything but the mn3007 that i got from Small Bear because I only have one...
I even changed out the transistors just in case...

anchovie

And at what point in the circuit do the highs disappear?
Bringing you yesterday's technology tomorrow.

Fender3D

#6
3007's pins 7 and 8 should be the same voltage,
pin 5 should be 0V,
pins 2 and 6 should be somewhat the same voltage AC though,
pin 4 somewhat positive voltage (~ the voltage on pin 3)
pin 1 is the only who has the right tension  :(

about 3101:
pin 1 OK
pin 2 should be the same as 3007's pin 2, it's the same actually, but it should have some voltage AC (it's clock!)
pin 3 GND OK
pin 4 should be the same as 3007's pin 6
pins 5,6,7 you should measure some AC voltage dunno what the DC could be
pin 8 should be the same as 3007's pin 4

maybe you reversed some chip or the PCB is wrong  :icon_eek:

"NOT FLAMMABLE" is not a challenge

george

I would
- check every resistor and cap AGAIN and ensure it is the right value
- check the pinouts on transistors if you are using substitutes
- check the orientation of polar caps
- go over each and every solder joint and ensure that the solder has flowed properly and there are no dry joints

The CE-2 has a trimpot but that only adjusts the bias on the BBD ie affects whether the pedal is chorusing or not.  It has no effect on the output volume/tone.

anchovie

Quote from: george on October 01, 2009, 08:33:03 AM
I would
- check every resistor and cap AGAIN and ensure it is the right value
- check the pinouts on transistors if you are using substitutes
- check the orientation of polar caps
- go over each and every solder joint and ensure that the solder has flowed properly and there are no dry joints

You wouldn't use an audio probe first to try and localise the problem?
Bringing you yesterday's technology tomorrow.