robb wrote:

i have a circuit board that appears to have had some mods done as
components do not match or blend with other components.

my concern for now is two polarized electrolytic caps that appear
to be used as "bypass caps" ??
i thought tantalum and ceramic were the best choice for bypass?
is this a problem ?

one is a electrolytic 1uF/50v polarized cap between 32v line to
Vcc2 on chip and 0v ref

32v dc ---- 36 ohm --|-- 1uF/50v (polar) (-) ---|
|
|
Vcc2
0v ref


and the other is an electrolytic 22 uF / 6.3v (polar) cap betweem
5v line to VCC on chip an 0v ref


any way i just recently read to use ceramic but i am wondering if
there is a reason one would want to use electrolytic ? or was
this just a dangerous amateur who did this ?

*OTHER Question *

there is a 36 Ohm 1/4 watt resistor ( orng blu blk gold )
between (inline with) the 32V supply volts to a Vcc2 pin on an
IC, what is reason to use this setup and could it be another
mistake made by previous repairer ?

thanks for any useful help,
robb


It depends what you are trying to bypass ?

The electro's types are basic caps and good
for local rail stability but do not work well in
preventing RF from traveling around. Using ceramic
type caps solves the issue of high frequency traveling
around.
it has to do with material used and construction
forms.
In most cases all you need is the electrolytic to
help stabilize local rail voltage on a particular
component how ever, if your circuit have functions of
generating RF or would be sensitive to stray RF then you
need to use caps for by pass that will work to suppress it.

You may find combinations of a low value non inductive type
cap being coupled side by side with an electrolytic.
This is performing 2 different jobs, not summing them.




--
"I'm never wrong, once i thought i was, but was mistaken"
Real Programmers Do things like this.
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