I just completed my amp but it won't start. When I turn it on my power led flashes periodically but does not stop even after 2min. I built the 19J6 version with the uppdated optional parts. I tried using one tube at the time and no tubes but it still flashes on and off.
The tab on the mosfets were isolated from ground before I soldered anything to them but now they are connected even when fully off from the casing. Is this normal?
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I have checked the wiring but can't see anything wrong with it. The powersupply I am using is this one http://se.mouser.com/Search/ProductDetail.aspx?R=GS25A48-P1Jvirtualkey63430000virtualkey709-GS25A48-P1J which is rated for 0.52A so that should be enough for the amp + 1 led that i run from a 10k resistor.
Edit: Picture added
The tab is connected to the drain, which is connected to V+ in the MSSH. So if there's conductivity between the tab and the case, it means your V+ rail is shorted to the case somewhere. What's confusing is the LED still works. For the LED to work, the short must not be a perfect 0 ohm short. A 0 ohm short would not allow the LED to turn on. What's the impedance between the tab of the mosfet and the case?
My first thought was maybe there's a short downstream of R13, but even a shorted R13 would not be able to overload the PSU. You need a short less than ~90 ohm to overload your PSU.