Jekyll & Hyde (gray) sometimes "fizzes out"

[flo]

I was a happy owner of an aging gray Jekyll & Hyde but lately it starts to have a problem while using the tube-screamer like side. At times (a bit unpredictable but often enough alas) it does the following at the same time:
- Sound starts to get more distorted.
- Sound starts to get more "fizzy" / "splatty".
- The signal only gets through when its loud, so only in the attack phase and gets cut off quickly as the signal fades out. Like a bad noise gate.

I tried to switch batteries but that usually does not fix it.
Its very annoying and I stopped using it which is to bad because I like the sound of it!
Then, after days or weeks, I'll try it again and usually it will work fine for an hour or so and then crap out again...
I checked / measured the battery power and the battery clip many times but that seems to be ok.

What can be the problem here:
- Bad solder connections somewhere?
- Bad foot-switches?
- Bad switching chip 4053, triple analog multiplexer-demultiplexer?
- Something else?

Please help me if you can. Thanks already for any suggestions you can give me.

Regards,
Flo.

[flo]

Link to switching part of the J&H:
http://i279.photobucket.com/albums/kk146/flo0987654321/Vs_jh_1.jpg
Rest:
http://i279.photobucket.com/albums/kk146/flo0987654321/Vs_jh_2.jpg

[Dragonfly]

send a PM to "R.G."

[R.G.]

... or just wait for the tone... 

flo, not to be a pain, but have you sent email to "service@visualsound.net"?

Visual Sound makes repairs to those things at very reasonable rates. The guy who does it knows them backwards and forwards, and has a supply of spare boards handy if it comes to that. The turnaround is usually 1-2 days in the shop, so you only add mailing time to that.

Beyond that, none of the issues you've guessed at are likely causes.

In any distortion pedal, when it starts getting hard to make sound, gate-ey sounding and fizzy, its bias has drifted off. If it drifts off slowly, it's almost certainly an electro cap that's gone/going bad and pulling the bias with it.

If for some reason you don't want to take advantage of what are *very* reasonable rates for repairs on those, the first step will be to replace every single electro cap. It's what I'd do with one of those if it were mine, before I even did any further debug.

[flo]

Thank for the reply but:
It can not be a bias problem because it is an intermittent problem: Sometimes it works fine and sometimes it does not. I think that when it is a bias problem, it would always sound bad, right?
So, please, any other suggestions perhaps on a common cause of this intermittent problem? Imo, they are the worst to fix!

Regards,
Flo.

[flo]

Oh, I forgot to mention: I did send a message to Visual Sound but did not get a reply yet. Perhaps I'm a bit impatient...

[flo]

I could of course try to measure the bias voltage when the J&H has gone bad and see if its wrong. Then I would know for sure, right?
The problem usually occurs after 30 minutes or so. Before that, it works just fine. It is also usually working good again the next day, for another 30 min or so. Could the bias voltage drift off very slowly while the pedal is in use and then sort of "restore" / "fix" itself when the pedal is not in use?

Regards,
Flo.

[R.G.]

Thank for the reply but:
It can not be a bias problem because it is an intermittent problem: Sometimes it works fine and sometimes it does not. I think that when it is a bias problem, it would always sound bad, right?

Wrong.
Who says bias problems can't be intermittent?

So, please, any other suggestions perhaps on a common cause of this intermittent problem? Imo, they are the worst to fix!

But you're correct there. Intermittents are much harder to fix because they're hard to find, and hard to verify the fix.

I could of course try to measure the bias voltage when the J&H has gone bad and see if its wrong. Then I would know for sure, right?

Maybe. If the process of opening it up does not disturb the grimy lead-to-plate contact inside the bias filtering cap that's really causing this, for instance. 

But if the measuring process causes you to bump into a part that makes the problem start/stop, then you may have found the problem.

The problem usually occurs after 30 minutes or so. Before that, it works just fine. It is also usually working good again the next day, for another 30 min or so. Could the bias voltage drift off very slowly while the pedal is in use and then sort of "restore" / "fix" itself when the pedal is not in use?

Of course it can. And that sounds very much to me like a bum capacitor which fails slowly under voltage, then repairs itself. There are several slow self healing mechanisms for both electro and film capacitors. This makes slow, soft failures like you're seeing very hard to find.

Oh, I forgot to mention: I did send a message to Visual Sound but did not get a reply yet. Perhaps I'm a bit impatient...

How long ago was that? 

[petemoore]

  i see RG's got a hit above this post.
  on and off sounds like 'pulsing' and that sounds like something capacitor might be caused to do.
  not that a resistor couldn't somehow pulse, or 'on / off' in some manner or other.
  It just seems like Hyde and Jekyll probably haven't really been around that long for capacitor dry out, perhaps something else happened.
  Intermittent is the worst, you can't count on it to work, you can't count on it to not work either.

[flo]

I had no idea that when a cap goes bad, it can cause this "time variant" behavior when voltage is applied to it. I was under impression that if the cap goes bad, it develops a lower resistance or something that is relatively stable and not time variant when voltage is applied to it. Caps that go slowly bad when in use and then fix themselves over time when not in use is also totally new for me.
Something new to learn everyday! Much appreciated.

Can these electro-capacitors go bad within 10 years or so? (How old is this gray J&H anyway? I got it second hand last year.)

I think I emailed them last friday so that's just two "workdays". But like I said, I'm probably impatient and posted here to see if somebody had an idea.

Regards,
Flo.

[Dragonfly]

The problem usually occurs after 30 minutes or so. Before that, it works just fine. It is also usually working good again the next day, for another 30 min or so. Could the bias voltage drift off very slowly while the pedal is in use and then sort of "restore" / "fix" itself when the pedal is not in use?

Of course it can. And that sounds very much to me like a bum capacitor which fails slowly under voltage, then repairs itself. There are several slow self healing mechanisms for both electro and film capacitors. This makes slow, soft failures like you're seeing very hard to find.

I think RG may have hit the nail on the head.

Often times that "drift" is indicative of a bad electro...

once the pedal is turned off, the electro discharges and returns to normal till its turned on again.

[GREEN FUZ]

It can not be a bias problem because it is an intermittent problem: Sometimes it works fine and sometimes it does not. I think that when it is a bias problem, it would always sound bad, right?
So, please, any other suggestions perhaps on a common cause of this intermittent problem? Imo, they are the worst to fix!

Regards,
Flo.

The pedal was designed to be this way. That`s why it`s called the "Jekyll and Hyde".



















Sorry, couldn`t resist.

On behalf of the Ministry of Disinformation.

[flo]

 

[R.G.]

I had no idea that when a cap goes bad, it can cause this "time variant" behavior when voltage is applied to it. I was under impression that if the cap goes bad, it develops a lower resistance or something that is relatively stable and not time variant when voltage is applied to it. Caps that go slowly bad when in use and then fix themselves over time when not in use is also totally new for me.
Something new to learn everyday! Much appreciated.
Can these electro-capacitors go bad within 10 years or so? (How old is this gray J&H anyway? I got it second hand last year.)

Think about a chasm bridged by a single wooden plank. Each time you walk across, it dips lower and crackles a little, but mostly recovers to almost where it was. Voltage is like pressure. When the pressure is removed, some conditions "recover" a bit before they totally break. Happens in a lot of things, not just electronics.

I think I emailed them last friday so that's just two "workdays". But like I said, I'm probably impatient and posted here to see if somebody had an idea.

I'll see what I can do. Where are you on the planet?

[jimbob]

Can you just buy a board? And would it be much cheaper?

[flo]

@R.G.: Great analogy, makes it clear: "voltage as pressure". I like it!

Where are you on the planet?

I'm living in the Netherlands.

I guess I'll be replacing these capacitors then...
Again, thanks for the help!