PEDAL VOLUME/GAIN DISAPPEARANCE URGENT PROBLEM!! PLEASE HELP!

[Nafe Parasite]

Hi, i am not a pedal builder or person of any electronics experience at all, but am experiencing an issue with a very beloved pedal, which is also fairly expensive and discontinued.
The pedal in question is the Pigtronix Mothership analog synth guitar pedal.
I'm struggling to find out what the issue could be and how to rectify it. Yesterday i was using it to record tracks in Logic on OSX, there was a fair amount of cable swapping from pedal to pedal going on, but was working fine. Today i plugged it in and there is a huge loss in volume/gain relative to the other pedals in my chain. I have toggled all possible parameters available and it has not rectified the problem. I am also not familiar with the inner workings of pedals, but an arbitrary thought came to me that maybe there has been a drop in voltage supplied to the pedal somehow. I am grabbing at straws probably.
I opened the casing today to have a deeper look, all i can report is that there seems to be no loose solder connections and no burns on the back of the circuit board. i have not disconnected fittings to inspect the underside of the board yet as i am not confident with my ability to not fry the circuit board. Also i don't know if i am smelling a burn out or whether circuit boards have a distinct smell, but nonetheless there is a peculiar smell coming from it.
What i would like to find out is has anyone else experienced this with a pedal, and how would i go about reinstating the correct volume?
other info if needed: the pedal voltage is 18v (on it it reads: 18VDC neg.tip), i am using a UK wall socket which supplies 220-240v. This was confirmed as fine by the manufacturers when i emailed them a while ago to make sure it would work.
Any help will be greatly appreciated!
thanks

[antonis]

<I have toggled all possible parameters available>
Which are..??

P.S.
Welcome..!!

[Nafe Parasite]

okay so i've just disconnected everything and removed the circuit board, i can see no burn marks. there is some dark glue spots on four solder points but no noticeable burn or smell. the parameters are labelled:
ring-mod level knob
ring-mod tune knob
ring mod footswitch
vco level knob
vco tune knob
vco wave switch (triangle - null - square waves)
vco fine tune knob
ring-mod source switch (vco - input)
engage/bypass footswitch
portamento switch (on - off)
whammy tune knob
guitar level/dry input knob
portamento knob
sub-octave level knob
master volume knob
sub-octave footswitch

Thanks

[antonis]

 
Well done..!!

How about IN/OUT jacks wiring..??
(or solder, in case of PCB mounted..)

[Nafe Parasite]

i couldnt tell you anything of any use from my limited knowledge, but here's a photo of the in/out jacks:







apologies for the poor quality photos. the first one is what the board looks like behind the lid, at the top it shows the 3 jack inputs (plus two on either side), the input jack is the top left and output jack is top right. The one in between them is an external whammy pedal input, the left side jack is an external portamento pedal input, and the right side jack is a sub-octave true output.

the other two photos shows the input and output jacks up close

[Nafe Parasite]

also here is a ceramic capacitor (i think) that is soldered above where the 18v power supply input is:








any significance in it's appearance?

also a pic of the underside of the board

[EBK]

I think that is a blown varistor rather than a ceramic cap.  Suggests that you may have had a major voltage issue.

[Nafe Parasite]

okay, thanks for your input.
do you think this is something i could replace with my simple ability in soldering? and do you know how i can tell which kind of varistor it is and if i can order one easily?
thanks

[EBK]

I think you should slow down just a tad.   

Consider this:
1.  That part failed due to conditions placed upon it by something else, possibly a faulty power supply or a faulty assumption regarding the power supply.  Figure out what happened there first, perhaps.  Otherwise, you could keep repeating this same scenario.
2.  When a protective device fails, its protection fails too.  Depending on how/when that happened, other stuff may have fried in that circuit.

Also,
3.  We're approaching the limits of my expertise.  I have no experience repairing this sort of thing, so I will happily defer to anyone else who has an idea of how to proceed.

[Nafe Parasite]

okay. well i can investigate the power supplies i was using and rectify those possible causes if that is what you mean. but until i do that i would simply like to have some reassurance either way; in the vaguest of suggestion do you think it is a write-off and i should save up and buy another Mothership pedal, or would it be worth taking it to my friend who's job is repairing musical electronic equipment and see if he can replace this blown varistor?
apologies for deflecting your last message, i will pursue your suggestions, but the urgency lies in the fact i am a working musician and this pedal is necessary to my setup.
thanks for all your help folks.
Nath

[EBK]

Perhaps try contacting Pigtronix and asking them what they think.  They may be able to provide valuable insight, and you've already successfully contacted them once.

[bluebunny]

If you're a working musician, I would expect you've got some kind of backup kit?  I'm only remotely semi-slightly-pro, but I've always got enough extra that I can at least make a sound.  Just sayin'...

Anyway, I'd look at whatever power supply (or power supplies?) you've had plugged in to this thing.  Your intial comment that it needs 18VDC but you're supplying 220-240V and you've been told that's OK is - I hope - a mis-statement.  I'm also in the UK and my mains supply is also 240VAC.  But I'm not plugging that into any of my pedals!      So show us the power supplies...

Next question: do you have a multi-meter?  We might need to start taking some measurements.  And no, don't throw it out.

...what am I saying??  Sure, it's busted.  Send it to me!       (Just kidding...  )

BTW, Eric's analysis is also quite correct: looks like a varistor (or a polyfuse?).  A simple fix would be to short it.  But I'm sure we'd all far rather sort out the problem than hide it.

[Nafe Parasite]

i may have emphasized the work 'working'. what i meant was, working towards...
anyway yes i have a multi meter. i'm not sure what you mean by shorting it, could you explain?
here is a pic of the power supply specs



edited: i'm going to buy a new 18v power supply

[aron]

I would test the power supply/adapter and see what it is putting out. Use your meter set to DC.

[antonis]

looks like a varistor...  A simple fix would be to short it.

I shouldn't dare to to suggest that, Marc..!! 
(in case of DC sources, varistors are usually placed in parallel with power supply in/out - like single phase line-to-line protection in AC power supplies..)

[bluebunny]

True that.  I was happier with "polyfuse".  Although the colour looked wrong?  Still, it *had* been cooked...

[EBK]

True that.  I was happier with "polyfuse".  Although the colour looked wrong?  Still, it *had* been cooked...

The board says V1 rather than F1 next to that part.  That's partly what led me to call it a varistor.  Plus, if you Google images of blown varistors, they look similar.

[antonis]

On the other hand, Eric, V1 label (+ blurred photo..!!) leads me to consider it some kind of voltage trimmer..

[EBK]

Only somewhat on topic, I love watching videos like this:

At around the 0:35 mark, the varistor starts fighting back with scifi plasma cannons.