Reply to thread

Message

<blockquote data-quote="envisionelec" data-source="post: 7671821" data-attributes="member: 640171">I hate working these mega amps....That said - there is a good chance that the Curie point of the transformer in question has been affected. This means that the magnetic properties of the transformer have been degraded by excessive heat and that the core must be replaced. What then happens is that the magnetic flux in a push-pull power supply &quot;walks away&quot; from being centered and a DC offset will result. This DC offset saturates the core and causes the FETs to excessively heat - usually just one bank of them - and only past a certain current draw.&nbsp; By the way, this can also be caused by an open rectifier on the secondary side. If you &#039;scope the transformer&#039;s primary, you&#039;ll see a huge negative voltage spike that will take out the FETs in short order.Good luck. You are amazingly brave to have worked on this amp.</blockquote>

[QUOTE="envisionelec, post: 7671821, member: 640171"] I hate working these mega amps.... That said - there is a good chance that the Curie point of the transformer in question has been affected. This means that the magnetic properties of the transformer have been degraded by excessive heat and that the core must be replaced. What then happens is that the magnetic flux in a push-pull power supply "walks away" from being centered and a DC offset will result. This DC offset saturates the core and causes the FETs to excessively heat - usually just one bank of them - and only past a certain current draw. By the way, this can also be caused by an open rectifier on the secondary side. If you 'scope the transformer's primary, you'll see a huge negative voltage spike that will take out the FETs in short order. Good luck. You are amazingly brave to have worked on this amp. [/QUOTE]

Verification