On Tue, 2006-08-01 at 21:29 +0800, Ling SM wrote:
> I need an approx. 48Vac (rms) source for some quick testing.  So I open 
> an adjustable DC wal wart, remove the capacitor, but found the maximum 
> tap I could get was about 24Vac.  As it is a 240Vac line here, and there 
>   is an option to switch the line select to 110Vac, I gave it a try 
> (actually 2 tries to burn 2 transformers).
> 
> With no load, the transformer burned out few second later.  The iron was 
> hot, and the primary side seemed to be burned out as it was measured 
> open.  I could not cut through the paper to see what had burnt last 
> night as they were hot, but they are gone now (thrown off).
> 
> Any ideas what could have burnt? coil shields or thermal fuse?

Too high a voltage = saturated core = LOTS of heat = burned out
whatever, probably several parts of the coil burned out.

> or more important question is there an easy way to get over the 
> limitation? so I can take advantage of the 110Vac selection in 240Vac 
> line to get a few more AC output.

No. Use the correct transformer. TTYL

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