Hi Pete,
I agree with Jim that that's probably just some flux residue. It
can't hurt to clean it off with some isopropyl alcohol and a toothbrush
(or the GC Hoghair brush, which is what I use...). A little rinse with
some distilled water after doesn't hurt either. While you are at it, I
would pick off those little blobs that you can see within about a 1"
(2.54cm) radius of the joint you are talking about (I think...they are
in a 90 degree arc from Pin-11 on IC-2).
A good solder joint is conical, thins out at the top where it
adheres to the lead, and at the bottom where it flows out to the edge of
the pad. Besides the type that Jim mentioned, other warning signs of a
bad joint are: rounded, blob-like joints, joints where you can't see the
end of the lead sticking out, joints where the solder has caved in
around the top where it should be adhering to the lead (looks like a
volcano cone with the lead sticking out). A variation on that last is
one where the lead has been bent after soldering and you can see where
it tore away from the solder cone, leaving a little gap on one side. On
double sided boards, little or no flow through of solder on the parts
side of the board can sometimes be an indication of a bad joint on the
solder side. There's many, many variations which I have seen over the years.
As an example, most of the joints on IC-2 in your pic look pretty
good. The exceptions being Pin-12, too little solder, and Pin-13 which
looks like it was drag soldered from Pin-14.
Best,
Ike
On 11-05-20 11:33 AM, pete wrote:
ike/all -
would this be an example of a "dry joint"? (see pic below - the white-ish
coloration around some of the solder points).
i would aim to desolder any points that look like this and redo. good idea?
pete
On May 20, 2011, at 11:01 AM, Ike wrote:
Yes, and the blast of signal is known as an "audio weld". With an old console, the fault
Matt describes could be anywhere, but I would start with the Molex connectors. Another point, the
same issue can also be in soldered connections that have either cracked from stress or become cold
soldered (or "dry" as they say in England) over the years. This usually occurs because
the joint wasn't that good to begin with. Over time contaminants work their way into the joint and
it loses conductivity. Again, the first place to look is the Molex connectors at the point where
they solder to the motherboard and the channel strip. Move the strips around and wait a day or two.
If the fault moves with the strip, it's a strip issue. If it stays with the position it's the
motherboard. Another Molex fault is loss of spring tension in the female headers. Try checking each
one with either a single Molex pin, or a tool that's about the same size.
And finally, exercise the switches on the affected modules. I don't know
if this is the case on the S-3, but on the Elite, the 48v switch actually
carries the mic signal so it can stop audio even when not engaged.
Best
Ike
Ike Zimbel
Zimbel Audio Ltd
416-720-0887
www.zimbelaudio.com
Sent from my iPhone
On 2011-05-20, at 10:28 AM, Matt Syson<[email protected]> wrote:
Hi
This fairly common 'gating' effect is usually caused by dirt on a connector,
switch or pot. An oxide film is created by chemical reaction of dirt and
contaminants in the air which create an insulation layer often a few atoms
thick. Putting a higher signal level through 'punches' a path through this
insulator (an absolutely miniscule spark) and for a while it will work
'normally' (usually with increased distortion). Then you switch off and leave
it for a day or so and the contamination starts its work again.
Dust, moisture in the air, smoke, all contribute to this.
Matt S
On 20/05/2011 14:27, pete wrote:
bros -
continuing the surely long and possibly never ending list of questions on my
series IIIc restoration project...
i am seeing the following behavior on the input modules (as well as the cue
modules)...
i'm feeding the line in with the multitrack output, and as i bring up the fader (and the
input gain) i get weak, fuzzy signal... until i jam the gain way up there (very quickly)
and the channel then "comes alive" so to speak. i can then bring it back down
to a sensible level and all is OK.
what problem is this behavior indicative of? bad connection to the motherboard? or a
component problem in the line in circuit? at the electrical level, how is a dodgy
connection "made OK" (in a sense) by pumping a greater voltage through it?
thanks all -
pete------
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