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Old 30th December 2012, 05:30 PM   #41
euro21 is offline euro21  Hungary
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3.) G2 voltage divider.
(454V-186V)/221K= 1.21mA
Original 09S divider (55K+33K) operate at 4.5mA!
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Old 30th December 2012, 08:37 PM   #42
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Thanks, I'm suspecting the e-choke as well, but I would like to avoid adding a lot of capacitors, maybe I have to try a real choke...
I don't think it is a ground loop or problem the hum/noise is 100hz so I think it must be coming from the power supply ?
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Old 30th December 2012, 09:01 PM   #43
euro21 is offline euro21  Hungary
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And what about the nonsoldered black wire near the input?
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Old 31st December 2012, 07:52 AM   #44
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Thats chassis ground, have tried it connected and unconnected, with same result
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Old 31st December 2012, 01:15 PM   #45
kevinkr is offline kevinkr  United States
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Take some really detailed pix of the interior of your chassis to show us how the grounding, filament wiring, HV supply are done, where the power and output transformers are located & oriented relative to each other - choke too if you are using one.

RCA jack is isolated from chassis and connected at the amp star ground?
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Old 31st December 2012, 02:41 PM   #46
nkdk is offline nkdk  Denmark
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Default hum

Hi
Try to move B1 to the other side of the echoke,i dont know the echoke,but are they wired op the right way ????
Increase the first cab after the rectifier tube to 30-40

nkdk
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Old 31st December 2012, 03:51 PM   #47
euro21 is offline euro21  Hungary
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I think there are two serious error in the power supply (based on the pictures).

1.) HV CT point connected to the e-choke ground (?) /black wire/, then e-choke other side ground(?) connected to the star ground.

2.) Where is the first 10uF capacitor? (IMHO 10uF too low for e-choke applications)

If the e-choke connected inversely, works like the short circuit (AC mode).

Last edited by euro21; 31st December 2012 at 03:53 PM.
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Old 31st December 2012, 08:26 PM   #48
dinoc is offline dinoc  United States
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Any good result of your baby? Actually I am starting to build the clone 09s as well, so that any information of you guys is very important to me. I am going to use Tomchr high voltage supply for my baby. Thanks. Click the image to open in full size.
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Old 2nd January 2013, 01:04 PM   #49
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Hi Euro21

I have tried some changes but with little result:
1) changed ground path, HV CP to star ground and E-choke ground to star ground:
Same result, no difference
2) Added a 330uF capacitor after the e-choke and moved MEC50 to after e-choke:
Reduced output noise from 58mV to 15mV but still way too much
Measurements:
before adding 330uF
output from e-choke = 448V 1,5Vac
output from MEC50 = 454V 2,2Vac

after adding 330uF
output from e-choke = 443V 356mVac
input to MEC50 = 443V 356mVac
output from MEC50 = 437V 180mVac

So still to much noise
What to do next

Do you think changing the G2 voltage divider will change something ?

3.) G2 voltage divider.
(454V-186V)/221K= 1.21mA
Original 09S divider (55K+33K) operate at 4.5mA!

Last edited by fonnesbek; 2nd January 2013 at 01:07 PM.
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Old 2nd January 2013, 02:04 PM   #50
euro21 is offline euro21  Hungary
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A: "Where is the first 10uF capacitor?"

Adding capacitance AFTER the e-choke not harmfull, but not sufficent, if C1 (10uF) missed, or low.

Schematic:
GZ37 rectifier diode -> C1 -> e-choke -> C2 - > R(100R) -> C3 -> OPT -> 300B
-> MEC50 -> R(33K) -> C4+C5
-> R(221K) -> C6
->R(100K)


In the picture I see only three large PP capacitors: C4+C5, and C6.

C1, C2, C3 are connected (CORRECTLY !) to the back panel under the e-choke?


B: "Do you think changing the G2 voltage divider will change something ?"
After solving the hum problem can be interesting.
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