Pedal Failure - FIXED

[zpyder]

Just an update - I opened my box up, removed one of the TL072's and the MAX1044, blew on them, put them back in, and now the unit seems to work fine  classic.  Anyways, just wanted to offer that up to anyone who may be interested.  Below is my original posting-



Hey guys,

it's been a while... I put together a layout based on RG's stuff and built an "Improved Hum-Free ABY" as per http://aronnelson.com/gallery/humfreeaby/Improved_Hum_Free_ABY_PCB (that is the layout I cooked up).

Anyways, it worked great for months, played many shows with it, stomped the hell out of it.  Now it is failing... the unit is grounding out the signal chain but only when plugged in.  Here are my symptoms:

> With the power UNplugged and the input plugged in, there is high resistance (no connection) between the input tip & sleeve.  This is what I would expect to see...
> With the power PLUGGED in and the input plugged in, there IS a connection between input tip & sleeve, but ONLY ONE WAY(!?) - I've never seen this before so let my try to explain:
  (When I place the negative probe of my multimeter on the sleeve of the input jack, and place the positive probe on the tip, I register ~120k ohms of resistance - evidently not enough to make my multimeter beep.  But when I reverse the probes (negative to tip, positive to sleeve) I get ~ -30k ohms of resistance (enough to make my meter beep).  This is trange to me.)

So the signal is getting grounded when the unit is powered, and the end result is that no signal comes out of either output jack irregardless of which output(s) I am selecting via the footswitches.

I am guessing that something has happened either with my transformers or with the MAX1044 I'm using to get the right juice.  Do those things ever go bad?

Any pointers or direction would be helpful before I totally rip the thing apart.
The outputs ARE isolated.  I am using 3PDT switches from aron.

Thanks!!
zpyder

[soulsonic]

Hmmmm..... that is one of the arguments I've heard against using sockets, they can lose contact with the pins and cause problems.

[Paul Perry (Frostwave)]

I only use sockets for chips that cost over $5, (when I'm experimenting) and for microprocessors.
I have never had a problem with a socket - but I don't use the cheap 'leaf' sockets, only the machined pin ones. Yeah, they are a lot more expensive - but, if you want a reliable socket, that is the one.

[zpyder]

Paul-

Small Bear seems to have machine pin ones here: http://www.smallbearelec.com/Detail.bok?no=100  for cheaper than the leaf here: http://www.smallbearelec.com/Detail.bok?no=144   

I am currently using the leaf style, but if machine pins are more RELIABLE through time/use/abuse then I'll switch...

thanks!
zpyder