No, assuming it did anything (it probably didn’t) it would have broken down the input transistor of the op amp which wont have killed it but would lead to it get progressively noisier until it eventually died.

The synth output would have to be very large to accomplish that.

http://www.kitrae.net/music/big_muff_history.html

Dig in!

But short story, it looks real and the date can be estimated by the code on the back of the pots (last 4 digits make up the week & year).

Also, you lucky…

I haven’t got a service manual for the pedal but it’s not too hard to work out what needs doing from the schematic and any tech worth their salt will be able to work out how to optimally bias them. There’s 3 trimmers, one sets the bias of both halves of the BBD, one sets the gain between BBD’s which in turn provides an equal 50/50 dry and wet mix and the final one balances the output section of the BBD, which is the one you’re probably most interested in as it will remove clock noise (just to clarify, clock noise as in a high pitched constant whine, not hiss or a chirping sound?).

Assuming it’s the constant whine mentioned above, you can probably adjust the balance trimmer yourself if you’d like to avoid a tech, it will be the one marked ‘1k’ just power the pedal on (being careful to keep your hands away from the power switch contacts/transformer section as this carries mains electricity) with nothing plugged in to the input jack, put the edge ‘on’ (the brighter mode) the blend CW (the vibrato side) and adjust it for the least whine, there will be a small section around the middle where the whine gets quieter, tweak it carefully until all the whine is gone.

Hard to say, a lot of “tech’s” will be DIYers who have no idea what they’re doing and will ask on pages like these for help, but there are some experienced folk out there. If you’re in the Americas, contact The EH Man on here.

Oh, if there’s no Zener that’s the early power supply variant which is prone to failure.

Here’s the EH service note that was sent out.

1)Replace the 2N5087 or BC309 transistor with a 2N4353 transistor.
2)Replace the 2N3563 transistor at pin 2 of the 741 with a 6.8V Zener.
3)Replace the transistor or Zener at pin 6 of the 741 with a 47k resistor.
4)Replace the 18k resistor with a 22k resistor.

So put simply you need to make it look like the version in the schematic on the metz site.

But there’s also a possible short somewhere in the circuit, I would test the 33uF & 100uF caps for continuity and if the 4013 is in a socket, try popping it out and seeing what happens to the supply voltage then.

Where are you located and what’s the problem?

EHX themselves don’t deal with the vintage equipment so unless you can do it your self, you will need a tech.

The EH Man does repairs in America, I can do repairs in Europe.

Your English is fine

If you’re in France and want it repaired (once lockdown is over) I’m in the UK and can fix it for you.

First off, unless you’re wearing an anti-static band, don’t handle that chip like that, CMOS are very static sensitive.

Second, while I haven’t traced it yet, a 4001 is a reasonable chip to be in there and you have ticking so there’s absolutely no reason to be suspicious of the chip I can see.

I would first be suspect of the switch itself so test it for continuity with your multimeter (middle pin should switch between the two outer pins with the switch) and the two tantalum capacitors in there, one is the turquoise cap, the other is the black one standing up.

They certainly can and do go bad but thankfully be replaced quite easily with more ‘modern’ regulators.

There’s a lot more that could be wrong before jumping to that though, could also be nothing wrong apart from the bad wall supply.

In the mean time if you want something productive to do, you could test all the electrolytic & tantalum capacitors for shorts with the continuity setting of your multimeter (assuming it has one).