Electro Harmonix Muff’n Pedal - Lights up but no ouput

woodworm

Has anyone had experience with the Electro Harmonic English Muff’n pedal ,  picked up a used one a couple of days ago but did not try it in store .

It turns on fine with one led showing in standby , when you press the on button the top LED comes on and the two valves light up but no output at all - when I turned the volume up on the pedal I can hear the "earth " hum increase but no guitar output. 

Any ideas on what it could be ?  

Thanks

ICBM

Does it pass signal in bypass?

woodworm

ICBM said:

Does it pass signal in bypass?

Yes  ,  with one LED on  the signal passes through fine when the switch is pressed and the top LED lights up it goes dead.

ICBM

Probably not the switching then, and definitely not the input jack. Best first guess is a dead valve. Try replacing each in turn with a known good one.

woodworm

ICBM said:

Probably not the switching then, and definitely not the input jack. Best first guess is a dead valve. Try replacing each in turn with a known good one.

Thanks , so if they light up it is not a sign that they are working ? 

ICBM

woodworm said:

Thanks , so if they light up it is not a sign that they are working ?

Not necessarily. It just shows the heater circuit is working.

It’s not the only possibility - there’s also a high voltage supply which could potentially have failed, or many other components. Checking the valves is the first and easiest step though.

smigeon

These pedals are wonderful and very much worth fixing IMHO. I use mine as a preamp; and with low-gain valves and the gain control turned down low-ish it livens everything up in a most beautiful way. 

If it’s something other than a valve that’s wrong, I had mine fixed by Jon at Mambo Amps (https://mambo-amp.co.uk/). In my case it was a little transformer whose job it is to produce high voltages internally. I remember Jon had a problem sourcing one and so when he eventually did, he got a couple in as spares. He may well still have them!

woodworm

Thanks for the comments , was hoping it was something simple .  I will  probably see if I can return the item as  I do not want to go to the expense of buying some  vavles only to find it maybe something else. Thanks again 

dano

I had the Tube Zipper years ago, those EHX valve pedals are pretty solid and well built. I sem to recall I had to change the valves on mine at some point as the ones EHX ship with were quite cheap. From memory these are all a similar circuit,  theyve got 3 gain stages and the final stage is the tone voicing. 

It's worth checking that the valves are seated properly. Make sure you've  discharged the caps though, try engaging the the switch to to on, plugged into an amp, and remove the pedal power for a few mins. 

I you could put a WTB on the amp section, see if anyone has some old valves they want to get rid of for a quick debug and swop them out. Otherwise it's back to the seller for a refund

ICBM

dano said:

those EHX valve pedals are pretty solid and well built.

Hmmmmmm…

dano

ICBM said:

dano said:

those EHX valve pedals are pretty solid and well built.

Hmmmmmm…

I guess you fixed more then ?! Maybe I've got some nostalgia for mine and plenty of tweaking it from FSB in the late 00s

ICBM

I don't think I'd describe any EH pedals as solid and well-built, really. Many of them sound great, many were quite innovative, and of course many of them were used on iconic recordings... but build quality and reliability has never been their strong point.