I've recently completed my SSE but the power supply is not behaving and I'm at a loss as to why - I've successfully built or restored countless tube-rectified amps, but I'm clearly missing something in this case.
The 5AR4's heaters light up, and the AC on the plates is correct, around 315V on each relative to ground. I'm also getting around 300 VDC between the cathode and ground. So far so good. I've tried two different rectifiers with the same result.
Both OPT secondaries have a load, and the driver and power tubes are not installed.
SW1 is not jumpered, and D1 & D2 are not populated.
The issue: I get *0* VDC across R2. I've replaced C1 as it was a pull from another project and I always suspected the solder joints due to short snap leads, but still no joy.
No blown fuses, no magic smoke released, no funny smells. Just no power downstream to the amp.
As an aside, I'd swear that this morning I measured R2 at a steady 150K, but now it fluctuates - my guess is that the meter is charging C1, causing the instability.
My next stab is to pull R2 just to rule out a dead short, but if that were the case I would be popping the fuse in short order and I wouldn't see any fluctuation when measuring resistance.
I've been over the web pages but they are presented a little differently from what I'm used to with the SE - my hope is that I'm missing a jumper or a part (wouldn't be the first time
) somewhere.
The 5AR4's heaters light up, and the AC on the plates is correct, around 315V on each relative to ground. I'm also getting around 300 VDC between the cathode and ground. So far so good. I've tried two different rectifiers with the same result.
Both OPT secondaries have a load, and the driver and power tubes are not installed.
SW1 is not jumpered, and D1 & D2 are not populated.
The issue: I get *0* VDC across R2. I've replaced C1 as it was a pull from another project and I always suspected the solder joints due to short snap leads, but still no joy.
No blown fuses, no magic smoke released, no funny smells. Just no power downstream to the amp.
As an aside, I'd swear that this morning I measured R2 at a steady 150K, but now it fluctuates - my guess is that the meter is charging C1, causing the instability.
My next stab is to pull R2 just to rule out a dead short, but if that were the case I would be popping the fuse in short order and I wouldn't see any fluctuation when measuring resistance.
I've been over the web pages but they are presented a little differently from what I'm used to with the SE - my hope is that I'm missing a jumper or a part (wouldn't be the first time
) somewhere.
Because it's not there. i found it while tracing the board for test points to pinpoint where the voltage was gotting "lost".
A Google search for the term "tubelab sse tr1" led me to a post (from 2012!) that descibed it as well as D3 & D4. Essentially TR1 is meant to accommodate a thermistor in order to help protect the rectifier - ironically, the tubes that need it the most are new production; the vintage Mullards are more or less unfazed.
A Google search for the term "tubelab sse tr1" led me to a post (from 2012!) that descibed it as well as D3 & D4. Essentially TR1 is meant to accommodate a thermistor in order to help protect the rectifier - ironically, the tubes that need it the most are new production; the vintage Mullards are more or less unfazed.
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