Fuzzdog Klone kit build help needed.

Red-mcmannus

Hi guys, first time poster. I apologies if I am posting in the wrong place, but I need some help with a Fuzzdog Klone kit build I am doing.

I have put the whole thing together, and it basically works, apart from one small fact which is that the gain control seems to only work as a volume boost, it does not seem to be getting up into actual gain territory. So the sound I am getting from it, is just beginning to get into the slightest bit if grit / distortion, but nothing like a Klon should be able to do.

I have checked the gain pot, given that it is a dual one, and confirmed that both layers are OK. However now I am not sure what I need to test to confirm why the gain is not actually adding gain like it should.

Do you guys have any ideas of what I can do to check or test what is wrong?

Any help or pointers would be greatly appreciated. 

Adam_MD

Can you post pics of both sides of the board?  It's easier to diagnose if you can see it.

Red-mcmannus

Hey, here they are - 

http://i.imgur.com/N6oxh0h.jpg
http://i.imgur.com/UgHf3IF.jpg

Adam_MD

I'd reflow some of your solder joints and have a look for any tiny solder bridges.  I don't see anything obvious from the pics.  

Red-mcmannus

Having reviewed some websites that analyse the klon schematic in more detail, I think the issue is with the Germanium diodes, as the TL072 is working in terms of adding clean gain, and the gain pot is working. 
I think it is the actual clipping that the germanium diodes do that is not working, as overall it is getting plenty loud enough, just no clipping to speak of. 

Gagaryn

Red-mcmannus said:

Having reviewed some websites that analyse the klon schematic in more detail, I think the issue is with the Germanium diodes, as the TL072 is working in terms of adding clean gain, and the gain pot is working. 
I think it is the actual clipping that the germanium diodes do that is not working, as overall it is getting plenty loud enough, just no clipping to speak of. 

Every chance you could have fried them.

Red-mcmannus

Yes I think you may be right. Is it expected that if they have failed that they will simply let the signal through unclipped? Is that a logical guess?

lasermonkey

Germanium diodes are easier to damage by excess heat than silicon diodes, though they shouldn't have fried under any normal soldering conditions.
The diodes on the Klon are "hard clippers", meaning that they are tied between the signal and ground. If they're damaged (open circuit) there just won't be any clipping at all. If you have a multimeter, set it to the diode/continuity setting and look for a reading of around 0.3 in both directions.
Other things to look for with the diodes: make sure they aren't cracked. The glass packages on Ge diodes are *very* fragile! Secondly, make sure that you have them the right way round.

Good luck!

lasermonkey

Sorry, just saw in the pic that the diodes are correctly orientated. D9Es? :-)

Red-mcmannus

Thanks for the info. Just took the diodes out all together and re tested the pedal, sounds exactly the same as before, so it looks as though they were not working.  Ordered some more, well, different ones. Can't seem to find D9Es. 

Gagaryn

Might be worth getting sockets too so you can audition the replacements without risk of damaging them. If the pedal is just being used at home the sockets are probably good enough to use longer term - if you are gigging you'd be wise to solder - making sure you use a heat sink on each leg o save them from damage.

Adam_MD

Red-mcmannus said:

Thanks for the info. Just took the diodes out all together and re tested the pedal, sounds exactly the same as before, so it looks as though they were not working.  Ordered some more, well, different ones. Can't seem to find D9Es. 

PM me your address and I'll send you some I've got a bunch in the house. 

Red-mcmannus

Hey Adam.  Just sent.