Re: Midas Board Power Supply

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Malcolm Watts" <m.j.watts-at-massey.ac.nz> 

Hi David,

On 10 Nov 2004, at 8:48, Tesla list wrote:

 > Original poster: "Harold Weiss" <hweiss-at-new.rr-dot-com>
 >
 > Hi All,
 >
 > I had a bit of fun recently on a show.  The show just got back to the
 > states from Japan, and had their electronics and set flown air cargo.
 > Once we got sound up and running we started smelling smoke.  We
 > tracked it down to the main console's power supply.  Upon opening we
 > found that a board containing a pair of toroidial xfmrs similar to
 > gate drive xfmrs had burnt to the point where the ferite actually was
 > burnt partially away. The regulators seemed to be laid out similar to
 > what I have seen in SSTCs and used a IFR140 (mosfet?) and a large stud
 > diode for each.  The supply also took down the backup supply which
 > should have taken over when the main supply died.  The xfmrs on the
 > backup supply were magnet wire, and may have had insulation failure
 > due to vibration.  Any other ideas on what may have taken it out
 > electrically?

Were the transformers in question power transformers or gate drive or
doing some other job? At what frequency would they have been running?
Sorry for the questions - I know nothing about that particular supply.
I presume the rectifiers were OK. A short on the secondary side (if
they are power transformers should have smoked the fuse/s on the
primary side if nothing else.

Malcolm