Schematic for Cort Multi Effect Pedal MIX-10

[Johnrcurry]

I'm working on a Cort "Multi Effect Machine" effect pedal. It is labeled "MIX-10," but there is a sticker on the box covering the "MIX-10" on all four sides. The sticker says "1443." The pedal will not power up and I need the schematic to try trace the fault. I've included some pictures of the item and the box. I really appreciate any help you may be able to provide.

Thanks

John

[mozwell]

Hi John, i dont have a sch & a web search doestn come up with much.
Rule out the obvious first.
Is the battery good, what is its terminal voltage.
Does each switch work ok, check with a meter on ohms between switch contacts.
Will the unit work from an external 9VDC supply.

If the power supply is getting to pin 4 & 8 of each 4558 IC. Is the power supply getting to each MNxxxx ic.
MN3207, pin 1 0V, pin 5 9V, MN3102 pin 9V pin 3 0V
Are the output pins of each 4558 sitting at 0V or 4.5V ?

The input goes to the distortion comp first, inject a signal & look at the output of each op amp, do you see signal there.
Is there a FET on the compressor, check it to see if its ok.

i would guess the internal circuits are copies of common pedal circuits. This box may lend itself to being stripped of parts & a new set of DIY effects built into it. The MN ic's if they are still good can built flangers, delays, chorus etc.

[Johnrcurry]

Thanks for the reply. I have tried it with both a battery and a separate power supply and the result is the same. The fact that none of the effects/LEDs etc. work suggested to me that it ought to be some global sort of fault. You've given me some good ideas for trying to track it down, and I appreciate it.

[J M Fahey]

Hi johnrcurry.

I have tried it with both a battery and a separate power supply and the result is the same.

makes me think that you have connected a wall wart and/or a battery and it didn´t start.
So far, so good (or bad )
But not enough !!!
What Mozwell says is that you don´t stop at that, but trace the +9V DC path, to see where you lose it.
Connect the black multimeter probe to ground, red to battery + terminal, you *should* have +9V !!!
(if not, then the ground connection is lost).
Then follow visually its path, along wires, tracks, switching contacts, connectors, whatever, into the pedal board.
You should eventually reach pin 8 in all dual Op Amps, where you should find +9V (or maybe a little less).
Probably their pin 4 is tied to ground.
Please post results here.
That old pedalboard is complex because of all the (analog) stuff they crammed there, but in fact it´s 4 very conventional pedals in a single case (and fed from the same battery).
Good luck.

[Johnrcurry]

Thanks, JM. I will follow your advice, along with Mozwell's, and post results.

John

[Denyle]

I had one on the bench this morning with similar issues (no sound, no led's lighting). There was no voltage going to the 2w amplifier ic (sorry, I forgot the part # already) and fault was with the nearby 2sc1815 transistor.

[Johnrcurry]

Denyle,

I appreciate your reply. I'd all but given up. Can you tell me which transitor it was based on the picture of the board I posted?

Thanks

John

[Denyle]

Denyle,

I appreciate your reply. I'd all but given up. Can you tell me which transitor it was based on the picture of the board I posted?

Thanks

John

In the 2nd pic, bottom right.

[Johnrcurry]

The one surrounded by capacitors?

Thanks again.

John

[Denyle]

The one surrounded by capacitors?

Thanks again.

John

Yup

[Johnrcurry]

Denyle,

I just wanted to report back that I replaced the transitor you identified as the possible culprit, and the pedal came back to life. It was just as you thought.

Thanks one and all for your help.

John