Original CE-2 Chorus problem

[AntKnee]

I figured some of you have enough experience with the pork barrel to help me out with my old Boss. I have an original MIJ CE-2 and its acting funny. Occasionally, and randomly, when I turn it on, the LED barely comes on and the sound is not quite normal. It seems like its not getting enough power. If anyone can give me any pointers, it would be appreciated.

Here's my voltages:
MN3007:
1 9.7
2 6.7
3 6.6
4 3.7
5 3.3
6 6.7
7 6.5
8 6.5

MN3101:
1 9.7
2 6.7
3 3.3
4 6.7
5 3.7
6 8.8
7 5.1
8 3.7

JRC4558:
1 7.4
2 7.4
3 7.4
4 3.3
5 7.4
6 7.4
7 7.4
8 9.7

TL0220P:
1 varies 5.1 to 8.8
2 6.4
3 6.4
4 3.3
5 varies
6 6.7
7 jumps back and forth from 4.0 to 9.0
8 9.7

[darrenw6000]

adjust the trim pot

[AntKnee]

adjust the trim pot

Really? After 30 or so years of normal operation? And the problem comes and goes randomly when I turn it on and off.

[Scruffie]

I'm not sure why your readings all have ground as 3.3V but i'll put that down to a measurement error.

By the sounds of it the problem is in the switching circuitry, it controls the LED and also the wet mix when the pedal is on.

Q6-9 on the original schematic, failure in the switching seems to be a fairly common fault so do some searching and you should come up with some previous threads that might point you in the right direction.

[AntKnee]

I'm not sure why your readings all have ground as 3.3V but i'll put that down to a measurement error.

By the sounds of it the problem is in the switching circuitry, it controls the LED and also the wet mix when the pedal is on.

Q6-9 on the original schematic, failure in the switching seems to be a fairly common fault so do some searching and you should come up with some previous threads that might point you in the right direction.

I was careful with my measurements. I dont know how that could have happened.

I will check into the switch fault problem.

[AntKnee]

Found this, and will give it a shot. Its not a bad part, but a product of using new power supplies with a circuit designed for an old power supply.

[Scruffie]

Ahh yes, i'd forgotten about that old chestnut, hopefully that resolves your issue then