Alt-BEAM Archive

Message #10090



To: beam@sgiblab.sgi.com =
From: Phillip A. Ryals =
Date: Thu, 10 Feb 2000 18:09:12 +0800
Subject: RE: Bicore question



ok, let me go one by one.

>Fast checklist:
> - are you absolutely, 100% SURE that every solder joint is good?
> Dave at Solarbotics reports that the vast majority of non-working
> robots they repair for people are due to solder joint problems.
I've gone over them three or four times. I have had problems with this i=
n the past, but I actually made a definite effort this time to get all good=
joints the first time.

> - is anything touching that shouldn't be? Solder accidentally
> bridging a gap? Leads touching in some obscure place? I like to
> run a dental pick between adjacent wires just to be sure (with
> power off !!!)
I always run a sharp knife between all the paths, just to make sure.

> - wash/clean off the soldering flux. Some fluxes are ever so slightly
> conductive. When you are using resistor values in the Megohms, the
> flux can sometimes make a difference.
ok, I didn't do this. How exactly are you suposed to wash it off? I'm u=
sing 2.2M resistors to get the speed down. On Andrew Miller's site, he men=
tioned that you can go up to 20M for certain apps, so I didn't think it wou=
ld be a problem.

> - did you install a decoupling capacitor across your + and - supply
> near the chip? Suggested value is between 0.022 and 0.1 uf. You
> rarely see this mentioned in circuit diagrams.
nope. does this definitely make a big difference? Should I just plan on=
it for every circuit I build?

> - did you "do something" with any unused chip INPUTS? Do something
> means connect them to either ground or Vcc. Unused outputs are NOT
> connected to anything.
I didn't do this either. Kinda misunderstood your question though. Shou=
ld they be connected, or shouldn't they?

> - are you using LED's to check your microcore behaviour? Are they
> installed right way around?
yup, to both questions. :) =




content-transfer-encoding: quoted-printable



>
danndom@mbox5.singnet.com.sg A>
Robotics =

Web Page(unfinished):

href=3D"http://home.crosswinds.net=">http://home.crosswinds.net/~danstryder/">http://home.crosswinds.net=
/~danstryder/
"It =

takes 99% sweat and 1% ingeniuty to have success" - Thomas =

Edison
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style=3D"BORDER-LEFT: #000000 2px solid; MARGIN-LEFT: 5px; MARGIN-RIGHT: 0p=
x; PADDING-LEFT: 5px; PADDING-RIGHT: 0px">
----- Original Message -----


style=3D"BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black">Fro=
m: =

Phillip A.=
=

Ryals

To: .sgi.com" =

title=3Dbeam@sgiblab.sgi.com>beam@sgiblab.sgi.com

Sent: Monday, January 31, 2000 11:=
22 =

PM

Subject: RE: Bicore question



ok, let me go one by =

one.

>Fast checklist:
>  - are you absolutely=
, =

100% SURE that every solder joint is good?
>    Dave=
at =

Solarbotics reports that the vast majority of =

non-working
>    robots they repair for people are d=
ue to =

solder joint problems.
I've gone over them three=
or =

four times.  I have had problems with this in the past, but I actual=
ly =

made a definite effort this time to get all good joints the first =

time.

>  - is anything touching that shouldn't be? =

Solder accidentally
>    bridging a gap? Leads touch=
ing =

in some obscure place? I like to
>    run a dental p=
ick =

between adjacent wires just to be sure (with
>    po=
wer =

off !!!)
I always run a sharp knife between all =
the =

paths, just to make sure.

>  - wash/clean off the =

soldering flux. Some fluxes are ever so slightly
>   =
; =

conductive. When you are using resistor values in the Megohms, =

the
>    flux can sometimes make a difference.
ONT =

color=3D#0000ff>ok, I didn't do this.  How exactly are you suposed t=
o wash =

it off?  I'm using 2.2M resistors to get the speed down.  On An=
drew =

Miller's site, he mentioned that you can go up to 20M for certain apps, s=
o I =

didn't think it would be a problem.

>  - did you in=
stall =

a decoupling capacitor across your + and - supply
>  &nbs=
p; =

near the chip? Suggested value is between 0.022 and 0.1 uf. =

You
>    rarely see this mentioned in circuit =

diagrams.
nope.  does this definitely make =
a big =

difference?  Should I just plan on it for every circuit I =

build?

>  - did you "do something" with any unused =
chip =

INPUTS? Do something
>    means connect them to eith=
er =

ground or Vcc. Unused outputs are NOT
>    connected=
to =

anything.
I didn't do this either.  Kinda =

misunderstood your question though.  Should they be connected, or =

shouldn't they?

>  - are you using LED's to check y=
our =

microcore behaviour? Are they
>    installed right w=
ay =

around?
yup, to both questions.  =

:)





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