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Old 20th September 2012, 12:02 AM   #21
kcshyan is offline kcshyan  Malaysia
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Following are snapshot of my tube amp driver stage. initially i'm using star grounding, then after than I switch to ground bus.
anyway, make no different.
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Old 20th September 2012, 12:07 AM   #22
kcshyan is offline kcshyan  Malaysia
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Really dun understand why the voltage draw to. I'm not sure is driver tube socket related or not.
Last night last experiments was disconnected all & re-do everything. I did on 1 driver stage alone without power stage. measurement look good. after hook up to power stage. the voltage dropped.
Now give me another question mark whether power stage is the root cause.
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Old 20th September 2012, 07:05 AM   #23
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There is a problem with your zener mounting, the two zeners are connected in series, but are the connected in the centerpoint (between the two) to pin 7 ???
And is that a 120R 5W resistor ?
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Old 20th September 2012, 08:55 AM   #24
kcshyan is offline kcshyan  Malaysia
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Thanks. Fonnesbek.

From the photo view, looked like connected. But actually not connected one.
I very careful & double check all the connection.
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Old 20th September 2012, 12:25 PM   #25
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Is the 5Watt resistor 120R or 120K ? should be 110K according to the schematics.
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Old 20th September 2012, 12:59 PM   #26
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your pic seems to show incomplete wiring.
so is G1 connected to the volume pot?
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Old 20th September 2012, 04:56 PM   #27
Salas is offline Salas  Greece
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Quote:
Originally Posted by kcshyan View Post
Following are snapshot of my tube amp driver stage. initially i'm using star grounding, then after than I switch to ground bus.
anyway, make no different.
Please keep pictures smaller, many have net books or I-Pads slower Wi-Fi, whatever. I fixed those already, just keep it in mind. Thanks.
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Old 20th September 2012, 11:20 PM   #28
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Yes, no path to the ground from the control grid may cause such a problem. Also if to solder electrolytics in cathodes backward their DC resistance may go south.
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Old 23rd September 2012, 03:33 PM   #29
kcshyan is offline kcshyan  Malaysia
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Thanks for everyone advises.
For time being, I modified my driver stage from c3m to 6SN7 while waiting for tube socket.
After modification, my 300b immediately working without any issue as mentioned above except power on time have "pop" sound. & this problem also solved by installed timer delay to delay on GROUND.
Cheers....
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Old 2nd October 2012, 04:23 PM   #30
kcshyan is offline kcshyan  Malaysia
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After few days listening to 6SN7 driving 300B, today I decided to try again with c3m. too bad it still not working & following are my step.
1) Remove all 6SN7 driver stage & remain power stage. I do on the LEFT channel only.
2) Change to c3m socket.
3) Wire up all the connection. Except VOLUME ground cable. Mean input not grounded.
4) Plug in the c3m.
5) Power ON.

Result
c3m plate voltage > 400v
Zener diode remain as normal.
Noisy sound like "tek tek tek tek"


Test
1) Connect Signal Ground. Plate voltage drop remain 5v

Observation
As long as my Volume connect to ground. c3m plate voltage sure drop remain 5v
if 2 channel, it will drop remain 2.4v

Why I'm so bad that c3m unable to work. Not sure is my power tran causing it or not.

Any advise.
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