New Build first power up...Bad News

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wrecked
Posts: 26
Joined: Fri Jan 14, 2005 6:43 am
Location: Canada

Re: New Build first power up...Bad News

Post by wrecked »

Hi Eric!

Thanks for the photos! Those voltages do seem a little low to me, as normally the 600Vct. specified for the B+ winding is at the rated current draw while in this case you're getting somewhere closer to 545Vct. at whatever fraction of the total load normal operation is. A good way to check if your PT is operating on spec is to measure the value of the heater voltage (it should be a little bit above 6.3V). If it's really close on that value, I'd probably shoot an e-mail to the folks at Heyboer and ask them if that voltage is right for the iron. I really hope you don't have any shorted turns in the HV secondary from those previous problems :(! Here's a homebrew Transformer Short Tester from Geofex if you want to check, though again, I'd talk with Heyboer first.

If the B+ you're getting is a normal, expected voltage for that transformer, I wouldn't worry about it too much. I use a bucking transformer setup with my Hammond iron to produce either 385V, 410V or 435V for the B+, and I'm sure that the very subtle differences between the lower two voltages could be tweaked out pretty easily in the circuit if one were so inclined. 385V is great to run 6V6es with too!

Those knobs look fine to me, although I think the real deal are the Davies 1510. I'm really looking forward to those clips!

Matt
RossH
Posts: 52
Joined: Mon Jan 17, 2005 4:35 pm

Re: New Build first power up...Bad News

Post by RossH »

snide wrote: I am floored nobody has ever complained about the bias circuit. It makes me wonder how many actually complete their build.
Eric
I'm sure it is something people just deal with, as well. I just lowered the first resistor to 150K, tied the pot wiper to ground, and pulled the bias leg off a different spot. That worked perfectly. Just another solution.

Ross
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Darkbluemurder
Posts: 584
Joined: Tue Jan 03, 2006 7:28 pm

Re: New Build first power up...Bad News

Post by Darkbluemurder »

RossH wrote:
snide wrote: I am floored nobody has ever complained about the bias circuit. It makes me wonder how many actually complete their build.
Eric
I'm sure it is something people just deal with, as well. I just lowered the first resistor to 150K, tied the pot wiper to ground, and pulled the bias leg off a different spot. That worked perfectly. Just another solution.

Ross
Ross,

I believe this is even better than the other variation. Should the pot wiper have an intermittent you would still have bias on the power tubes. Clever solution!
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