fatman, glowing cables, etc.

[Arthur Harrison]

Joe Miklojcik wrote:

>I'm looking at my Fatman, my first forray into the world of electronic
>assembly.  Most of the joints are dull, made with the lowest of the low
>rat shock irons (only hot enough to melt solder during 20% of its
>thermostat cycle).

Does it actually have a thermostatic control?  It couldn't be too cheap,
then.

>I think I could have used better solder too.

I suggest a 0.032" diameter solder for general-purpose through-hole
applications (conventional DIPs, resistors, capacitors, etc.)  Alloy 63/37
(63 percent tin, 37 percent lead) and a "RA" (that means "activated resin")
core works well.  One possible type is Ersin's SN6321GA1LB (one pound roll).

>I think I'm going to have to build a new one with my nice Weller and some
>decent solder.  Anybody have any tips on things I can do to salvage the
>old one?

Thoroughly remove the existing solder using solder-absorbing braid
(I like to use Chemtronics brand "Soder-Wick" type 80-6-5) and a
single-flat iron tip such as Weller part number PT-AA7 (this tip regulates
itself
at 700 degrees F) in a Weller WTCPT soldering station.

Remove all flux residue with an appropriate solvent, short-bristled brush,
and ample paper towels.   I don't recommend submerging PC boards in solvent,
as doing so might damage components.  Another useful tool for solder removal
is a hand-held, manually activated, vacuum pump such as Weller's WDP12.

>I want to use ten turn pots on at least the osc tuners of fatman2.  The
>Mouser catalog I have lists some, but doesn't give me an impression of
>how durable they are.

I use the Bourns type 3590S 10-turn pots.  They are moderately priced,
7/8" diameter units, and are quite durable. Smaller-diameter 10-turn panel
pots tend to be expensive.

BTW, since many 10-turn pots are more inductive than one-turn carbons,
be aware that this inductance can cause problems in certain high-frequency
circuits.  (This certainly should not be a problem in things like voltage
summing
circuits or VCO pitch scalers, though.)

Lately, the price of single-turn conductive plastic pots have been dropping.
Consider single turn conductive-plastic types to replace carbon
potentiometers;
they have much better setability and don't get "scratchy" as easily.
I saw the Mouser c-p units and was surprised at the relatively low prices;
these might be worth a try.

>Also, I'd like to use smaller (narrower) knobs to
>allow more room for fingers between knobs on the front panel.  Tips?

Alco has a 0.47" diameter knob that accepts a 1/4" shaft, part number
KB-500B-1/4.  Since many potentiometers are made with 1/8" shafts,
also consider KB-500B-1/8.

>I think I'm going to start using clear lucite or some other clear,
>thick, sturdy plastic for front panels.  Does the front panel of the
>FatMan have to be alluminum for grounding purposes?  (Or the PAiA
>9700s?)

Aluminum would certainly be my choice of materials for it's durability,
machineability, cost-effectiveness, and electrostatic shielding properties.
The shielding is an asset, regardless of whether the manufacturer uses
the panel as a current-carrying ground.

>My last question: I'm fascinated by the glow in the dark guitar cables
>I see in gearwhore magazine^H^H^H^H^H^H^H^H^H^H^H^H^H^H^H^H^H^H the
>musician's friend catalog.  Does anybody know where I can get a good big
>spool of this stuff?
>
>Thanks.  You're all my best friend now.
>
>(jfm3)
>
>