Re: Apple ][ original power supply restoration (Pt 2)...

[russotto@grace.speakeasy.net (Matthew Russotto)]

In article <1143630692.248836.53080@i40g2000cwc.googlegroups.com>,
Nama <lord_philip@mac.com> wrote:

>I read somewhere that this could be a sign of a short, or signify
>another problem. I have looked for shorts and can not see anything
>obvious. and all resistors look solid and not burnt in any way.
>
>Taking voltage reading I get the following:
>+5V line = 1.6V
>-5V line = -0.8V
>+12V line = 1.8V
>-12V line = -0.8V
>
>...these voltages also pulse a little in time with the chirps.
>
>I was wondering if anybody would be able to suggest where I should look
>next? Rectifier maybe?

Note that you can't run it open-circuit.  The usual way of testing a
switching power supply is to connect a headlamp across the +5V line.
If it still chirps, something is shorted, likely one of the capacitors
you didn't replace.

-- 
  There's no such thing as a free lunch, but certain accounting practices can
  result in a fully-depreciated one.