Delay problem with J-Fet Vulcan

[EdJ]

Hi.it`s been a while:-)
Anyway here`s the problem;i have a J-Fet Vulcan that has a strange problem.
If you turn it on you hear nothing and after a few seconds it cuts in and  is working fine.
I suspected the switch so i replaced that but the problem is still there.
I guess it could be a capacitor charging but that is just guessing.
Does anyone has an idea what this is (and how to fix it)?

Thanks in advance.Ed

[aron]

Every time I have heard of this sort of thing, it's been a capacitor oriented incorrectly. I haven't seen this myself in a long time - but it did happen to me long ago. I guess triple-check the electrolytics.

[alanlan]

It looks that way.  I'm not saying this is the cause but it's a possible one:  if you look at the input cap, when you power on it is going to charge up through the 1M and 10M resistors.  Now 11M*0.1uF is 1.1 secs time constant, so we're somewhere in the range of the effect you are seeing.  Perhaps that has something to do with it?  The best place to measure this would be on the source of the first FET with a DMM.  I suspect you may see this charging up slowly but as I say, this is just a bit of a guess.  I haven't analysed it too much.

<edit>  Also, are you powering the unit up each time you engage the effect?  i.e. isn't it powered up all the time, so wouldn't the effect you are describing only be a problem when you plug the unit in for the first time?

[EdJ]

Thanks guys.i`ll check your suggestions out.
Btw.it happens everytime i engage the unit,not just on the first power up.
When it finally works,it works just fine that is why i thought the electrolitics were placed right but i`ll look things over.

Greetings,Ed

[EdJ]

Update:the electrolytic is oriented correctly.
the JFet is indeed charging up slowly.
I will take out the inputcap and replace it tomorrow(not a fun thing to do as i is build on this tiny perfboard).
Might need to borrow some glasses first:-)
The thing sounds wonderfull when it works though.
Greetings,Ed