[sdiy] Welcome to the Twilight Zone

[Peter Grenader]

This sounds like my nightmare here.  I used (shutter) those Radio Shack wire
kits they make for press-in protoboards for the vector board solder
connections in this board.  I don't what they do, HOW they do it - but
somehow Radio Shack has a propensity to make things that are designed to be
soldered (like tin plated wire) extraordinarily unsolderable.  Try their
copper plated vector-type boards.  total joke.  Coarse, if you use THEIR
soldering irons (as large as a 50 MM bullet tip) and solder (about the
diameter of the cabling that suspends the Golden Gate bridge), I guess
anything is possible.

I usually have to use a flux len when soldering these just to get it to
flow. So I bet ya some are starting to fail - not that they were ever good
solder joints to begin with.


harrybissell wrote:

> Two thoughs...
> 
> 1) phase reversal on one of your opamps...
> 
> 2) ultrasonic oscillation on an opamp
> 
> 3) some flakey connection on the circuit board
> 
> any one might give the symptoms you describe.  I got hit with #3
> about three years ago at AHMW.  My quantized theremin failed to
> work. I field stripped it and lo, it worked. I has concluded grounding
> problem at that time (I had not used it with the full PA system)
> 
> Later found that a connection on a critical voltage reference was not
> soldered correctly. I use Vector T-42A pins... and the solder had
> bridged the TOP of the pin but not wicked down to the lead.  Push
> one way, works, another... don't work.   This impersonated another
> problem.
> 
> oh yeah, I forgot #4.   I DID warn you about those "fatties in the
> parking lot at lunchtime".   If I was your boss... I'd FIRE you. Since
> you are your boss, I guess you'll have to make the call...   <bfg>
> 
> H^) harry
> 
> Peter Grenader wrote:
> 
>> Thought I'd share a bit of bizarro behavior which occurred late last night.
>> 
>> When putzing around with the prototype Plan B (vector board) all of the
>> knobs except the PWM and FM attenuator - the Freq, fine tune, even the two
>> bipolar freq VC attenuators - suddenly operated in reverse.  Turning the
>> freq pot CCW made the pitch higher.  Turning a freq VC attenuation pots
>> fully CCW processed the VC fully positive (should be the other way around).
>> 
>> Turned the power off - still there.  repeated that a few times - still
>> there.  So then I put my VC Input through an external processor to invert in
>> before it went to the VCO to see if I could fake the VCO out and when
>> turning the offset knob on that processor in a  positive (more voltage)
>> direction, I suddenly noticed that the controls returned the 'normal'
>> operation on the VCO.
>> 
>> They are all running off the same supply.  However, in the name of science
>> and unparalleled universes, all of the effected controls do run through the
>> same op amp internally (they are summed).
>> 
>> Too weird and yes, I did check for flying donkeys outside and no, my cat did
>> not begin to bark during this time.
>> 
>> Now off sign to going I'm,
>> 
>> - P
>