Random DEC Questions

Robert Jarratt robert.jarratt at ntlworld.com
Thu Dec 4 16:27:14 CST 2014

> -----Original Message-----
> From: Jarratt RMA [mailto:robert.jarratt at ntlworld.com]
> Sent: 01 December 2014 21:19
> To: General Discussion: On-Topic and Off-Topic Posts
> Subject: Re: Random DEC Questions
> On 1 December 2014 at 06:16, tony duell <ard at p850ug1.demon.co.uk> wrote:
> > Not sure what makes it an international model, although it does say
> > 50-60Hz, and it does not have a captive power cord, so presumably it
> > is an international one. I will have to take a look inside, but I
> > really don't have any idea what I would need to do to convert it.
> Nothing specific to the VT3xx
> Normally SMPSUs that can be converted to run off 115V or 230V mains run the
> chopper off about 350V DC. The mains input rectifier circuit is configured to be
> a simple bridge rectifier for 230V and a voltage doubler for 115V. The
> conversion is nothing more than a link from the neutral side of the mains to the
> centre tap of a pair of smoothing capacitors in series (if you look at the circuit,
> you end up with 2 diodes that are redundant, always reverse-biased, in the
> voltage doubler circuit, but that is no problem).
> So look for a link on the PSU board in this area. If you are lucky it will either
> have 2 positions labelled '115V' and '230V' (in the latter position it actually
> does nothing) or will be marked 'fit for 115V' or something.
> -tony
> Thanks for the suggestions from Glen and Tony. I am away from home most of
> the week, but I will take a look when I get home again at the end of the week.
> Regards
> Rob

I opened up the VT320 tonight. The PSU is set for 240V, which is good. However, I noticed some corrosion around the flyback transformer. I have posted a picture here: http://1drv.ms/1zqDhx5

This looks like corrosion of some kind of retaining clip perhaps, rather than anything functional. Am I right, or should I be concerned?



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