EHX Big Muff V5 1978 battery wiring question

[paulrm]

I bought a broken EHX Big Muff V5 on ebay, the battery clip was detached. From what I could see, the black wire from the battery connected to the guitar input earth, and the red connected to the 9v plug. This worked and the pedal is now working. I've made lots of guitar pedals but never seen the earth of the guitar connected through the battery with no other each connections. Normally the earth is soldered to almost everything inside the box. I can't tell if the battery has to be connected to use the 9v DC only and if connecting the 9v disconnects the battery. I can't see how it would as it seems the battery would be connected to the earth of the DC power cable? Incidentally this pedal sounds much better than the clone that I built which is frustrating. Hearing the actual vintage pedal is an ear-opener in terms of cloned pedals I think.

[feddozz]

My 2 cents:

1. the guitar (input jack?) earth might be connected to the box. A DMM will tell you
2. a DMM will tell you if the guitar is disconnected when a DC jack is inserted. I would do this check with a DC jack not energized (probably not necessary but cautious)

[paulrm]

Ah yes that makes a lot of sense, I'll check this out. Thanks very much.

[paulrm]

I checked the pedal last night. Yes, the input jack earth is connected to the case, so is the 9v input plug, and so is the earth on the output jack. The actual circuit doesn't seem to be connected to this earth. The 9v doesn't disconnect the battery either, but the pedal works fine with the 9v connected and the battery removed. Thanks for your help, very enlightening.

[antonis]

The 9v doesn't disconnect the battery either,

If so, then it should disconnect battery's Ground, but it should happen in Positive GND circuit..

It seems odd to me a simultaneus PS plug and battery working condition (even in case of a rechargeable battery..)

[digi2t]

The power switch from V4 was converted for use as the tone bypass switch. According to this trace, they used the output jack for power switching. This is kind of weird, considering how many pedals use the input side to do this.