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In the Forum: Melquiades Amplifier
In the Thread: Planning my DSET
Post Subject: Finally firing up the DSETPosted by anthony on: 12/31/2018
Hi Romy,

What a busy year just gone!  Finding enough time to just sit down and get the DSET's going has been impossible, but I have time now and have started the process.

At the moment I am introducing some high voltage to the first amplifier chassis, only the Bias and First Stages (for A, B, C channels) - no HV yet for Second Stages, Single Stages or DHT Channel (my DHT has its own power supply).  All tubes for all channels are in their sockets.  It is confounding me.  Firstly, the -200V Bias supply takes ages to come up to voltage but it does get there...no issues for the +200V side, it charges is 200uF caps almost instantly, but 9,000uF on the negative side takes almost 90 seconds to get to -200V, and the negative 0A2 does not light up until about 90 seconds after the bias supply starts to power up.  There is an issue there...how long does it take your negative 0A2 to ignite Romy?

Secondly, and these issues may be related, the First Stages 6E5P (for Channels A, B, C) are not behaving as I would expect.  I've checked the wiring a number of times and as far as I can tell it matches the schematic, and while A and C sit at about 200V at their anodes, Channel B sits at 400V or so and its 15K 12W resistor is staying cool and not drawing any current which means that the tube is not conducting.  I've checked resistances from the tube socket to other parts of the circuit and swapped tubes and nothing changes.

Romy, are you able to think of something that could be causing these problems?  I think it likely that they are both linked to the same fault, but I just cannot put my finger on it.

Happy New Year,

Anthony 

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