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Old 16th April 2003, 04:30 PM   #21
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Dimitry,
Looks great. What are the dimensions of the case your using?
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Old 16th April 2003, 05:38 PM   #22
mig-ru is offline mig-ru  Russian Federation
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Well with further inquiries into the problem, moving wires, etc... it looks like the hum might be from the filaments, i think i will try add two 100 ohm resistors between the 6SL7 filament connection to ground and see if that helps. As for the transformers, I got them on Ebay from handwoundtransformers.com, kind of a gamble, but turned out to be very high quality stuff. Last, the dimensions of the chassis are 17"x10"x3".
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Old 16th April 2003, 06:10 PM   #23
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Quote:
Originally posted by Joel


Yuck! 220uF is 180uF too much, IMO.

Why? I agree that 220uF is a good idea, though better placed after the resistor, where power flows into the OPTs.

Tim
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Old 16th April 2003, 06:13 PM   #24
mig-ru is offline mig-ru  Russian Federation
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Default not filter.

guys it doesnt sound like 120Hz, so I think the PS section will be left alone for now, that's why I think its the filaments, because the primary and HV winding wires are out of the way. thoughts??
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Old 16th April 2003, 06:28 PM   #25
Joel is offline Joel  United States
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Quote:
Originally posted by Sch3mat1c
Why? I agree that 220uF is a good idea, though better placed after the resistor, where power flows into the OPTs.
Nope. Move the 800 ohm resistor directly after the rectifier, and increase the choke to 15 or 20 henries. Make both caps 40uF, and you'll have a happy PSU.
I've gone down this road many times, and a 15H choke (or two) usually ends up making things right. Large capacitors never seem to.
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Old 16th April 2003, 06:28 PM   #26
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Then in that case, you can try the hum-bucking arrangements by Steve Bench or try DC fils.

Tim
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Old 16th April 2003, 11:10 PM   #27
mig-ru is offline mig-ru  Russian Federation
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added the 100 ohm resistors to the 6SL7 filament connections, barely any hum now!!! now i can enjoy it 100%.
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Old 16th April 2003, 11:36 PM   #28
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Default Killing the hum

So, Dmitry, way to go!

Am I correct that you put in basically a hum pot (200 ohm) with the wiper to ground and that was successful?

Just curious,
Rick
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Old 16th April 2003, 11:51 PM   #29
mig-ru is offline mig-ru  Russian Federation
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basically, but not hum pot, just resistors.
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Old 16th April 2003, 11:52 PM   #30
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Default Rs.

Hi,

Yup, just the resistors can kill the problem...I fully agree.

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