Battery Damage to EHX NEO Clone

[ReverendoRyan]

Hey gang!

I'm taking a look at a Neo Clone for a friend, who unfortunately had a battery leak inside it. Symptoms are no chorus effect (clean passes through) and no lead.

First operation was to open it up, clean the corrosion. Nothing too bad on the board, the ribbon cable was a little damaged. So I took care of that first. Still nothing.
Decided to do a litte probing. Signal is coming into the circut. Once through it does go to the MN3207, and I am getting vibrato effect on the appropriate pins. The trimmer is doing it's job (small window of vibrato effect) and the C1M pot is affecting the rate.

Its almost as if its not "summing" Clean + Vibrato before going to the pedal output, just the clean shorting to output.

Concerning the LED, I know it's not fried because when I short it out it still lights up. There must be a short somewhere? I can take some pics of specifics if need be, but does anyone have experience with something similar?

 

[Nostradoomus]

Pics would be very helpful, the more eyes on it the better.

 

[ReverendoRyan]

You're right, here's some pics, if need be i can take some more if anything jumps out

 

[jwin615]

Where was the leakage at on the board? Between U1 and the C1M? Seeing some vias that look like they're missing plating.

 

[ReverendoRyan]

It was pretty contained to just where the battery sits, I've circled it in red, so I'm not too sure anything corrosive actually got on the board

 

[Robert]

Are you absolutely sure the wires to the 3PDT didn't get mixed up in some way?

That's the common point that could affect both the signal path and the LED ...

 

[ReverendoRyan]

Are you absolutely sure the wires to the 3PDT didn't get mixed up in some way?

That's the common point that could affect both the signal path and the LED ...

yeah, i did the connections one by one...

 

[Fama]

Are you sure it gets toggled? Because if it was always on bypass, that would also explain the symptoms - basically what Robert said, but in a different manner (probably broken 3PDT instead of the wires being mixed up).

I guess since you probed it, that should have shown you if the chorus signal gets to the footswitch but not to output, so probably not it.

For figuring out the summing part of the circuit, a schematic would be useful, but I didn't find one with a quick search. Can you trace forwards from the BBD, or backwards from the output, to see if you can find where the vibrato signal disappears?

 

[andrewsrea]

The battery leak may be coincidental, and your lack of vibrato may be something else. Do you know if you are getting vibrato signal at the mixer?

 

[falco_femoralis]

Symptoms are no chorus effect and no lead? What do you mean by lead?

Do you have a schematic of the signal path?

Where does the LED get its power from? Does it pulse with the LFO, or constant on?

If it's constant on, then you should pretty easily be able to trace it back to where it gets its power, or where its ground terminates. This should lead you do the problem

You are also going to want to trace your wet signal all the way thru to where it drops out. It's good that you're getting it after the 3207 chip, that's a good sign.

One thing that could affect the LED and the "summing" is the power section. If the LED is not receiving power, and the op amp stage at the end is not receiving power, then you will end up with the symptoms you have described. I would trace them both back to where they receive their power, and where their grounds are at, and see what you find.

 

[ReverendoRyan]

Thanks for all these insights, it will give me stuff to work on. I'm on a work trip till next weekend, but will do as advised....