[Johnson] Invader 200 Power Supply components question.

Thu, 20 Feb 2003 15:52:23 -0800 (PST)

Joe,

 You may also use  higher value caps with lower working voltages. You will have
to change out the equalizing reisitors. A value of 100 ohms / volt is
satisfactory.

  The new equalizing resistors will be equal to 100 * WVDC of the cap. And of
course you must calculate the power as E * E / R. Double this rating for safe
tolerance of dissapation in the resistor.

  A while ago I bought a box of 400uf @ 200 vdc. I have used them quite
successfully in filter bank replacements for a host of BA sets

  So in my case of the 200 v caps  the calculated value would be 20K at 4 w
across each cap. In reality I put 2 47K 2W for a total of 23.5K  across each
cap.

  Why all the fuss  with extra resistors and low voltage caps? Well, frankly
they were a bargain and they work very well. The downside is of course they
take up almost twice the real estate  as 450wvdc caps - lots of blue cylinders!

  73
  de KA4JVY
  Mark

--- Joe Y <[email protected]> wrote:
> Hi all,
> Looking still closer at my Invader I notice what
> appears to be one of the 60uf 450 v electrolytics
> leaking, I am fairly certain that it will need
> replacement.
> 
> It seems that 60uf in that voltage is not available
> the closest I can find is either 75uf and 47uf. I am
> wondering if I can use 75uf with out stressing out the
> transformer and choke. I'm dont think the 47uf will be
> large enough but not sure.
> I really want to avoid using 2 caps series or parallel
> to get 60 uf as I would like to swap all 3 of the
> 60's. Has anyone repelaced them in the invader or been
> in a similar situation?
> Thanks again for any help
> Joe
> 
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