Yamamoto 09S 300B SE Amp Problem - Page 2 - diyAudio
Go Back   Home > Forums > Amplifiers > Tubes / Valves

Tubes / Valves All about our sweet vacuum tubes :) Threads about Musical Instrument Amps of all kinds should be in the Instruments & Amps forum

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 19th September 2012, 03:26 AM   #11
diyAudio Member
 
Wavebourn's Avatar
 
Join Date: Sep 2006
Location: Pleasant Hill, CA
Send a message via Skype™ to Wavebourn
Do you have 2.4V on cathode and 66V on screen grid?
__________________
"Our youth [...] have bad manners, contempt for authority; they show disrespect for their elders, contradict their parents, [...] and tyrannize their teachers. -- Plato, 447-367 BCE
  Reply With Quote
Old 19th September 2012, 05:42 AM   #12
kcshyan is offline kcshyan  Malaysia
diyAudio Member
 
Join Date: Sep 2005
Hi, Wavebourn.
Yes , I did measured 3.1v @ cathode & 95v @ screen grid. I slightly changed the zener value to increase the screen voltage. & this been successfully tested on my friend system.
  Reply With Quote
Old 19th September 2012, 05:50 AM   #13
diyAudio Member
 
directdriver's Avatar
 
Join Date: Nov 2005
Yamamoto A-09S schematic.
Click the image to open in full size.
  Reply With Quote
Old 19th September 2012, 05:56 AM   #14
diyAudio Member
 
Wavebourn's Avatar
 
Join Date: Sep 2006
Location: Pleasant Hill, CA
Send a message via Skype™ to Wavebourn
Quote:
Originally Posted by kcshyan View Post
Hi, Wavebourn.
Yes , I did measured 3.1v @ cathode & 95v @ screen grid. I slightly changed the zener value to increase the screen voltage. & this been successfully tested on my friend system.
So if you increased voltage on screen grid you need to increase as well resistance in cathode. If B+ is 385V, you have 10V on anode, that means current is 375/110 mA. The tube is probably saturated.
__________________
"Our youth [...] have bad manners, contempt for authority; they show disrespect for their elders, contradict their parents, [...] and tyrannize their teachers. -- Plato, 447-367 BCE
  Reply With Quote
Old 19th September 2012, 06:07 AM   #15
kcshyan is offline kcshyan  Malaysia
diyAudio Member
 
Join Date: Sep 2005
Wavebourn,
Thanks for your fast response.
What is your advise ? Increase the cathode R ?
I'm planning to reduce B+ to less than 300v. What is your opinion ?
Appreciate your valuable advise.
  Reply With Quote
Old 19th September 2012, 09:13 AM   #16
diyAudio Member
 
Join Date: Jun 2008
I'm building a clone too. One thing I have noticed is that the resistor values are very different in the production a09s compared to the ones in the schematic.
Maybe a stupid question, but are you using 20volt heater on the c3m ?

Last edited by fonnesbek; 19th September 2012 at 09:19 AM.
  Reply With Quote
Old 19th September 2012, 09:26 AM   #17
palmas is offline palmas  Portugal
diyAudio Member
 
Join Date: Jun 2007
Quote:
Originally Posted by fonnesbek View Post
I'm building a clone too. One thing I have noticed is that the resistor values are very different in the production a09s compared to the ones in the schematic.
Maybe a stupid question, but are you using 20volt heater on the c3m ?
Yes, C3m filament is 20V!
  Reply With Quote
Old 19th September 2012, 09:28 AM   #18
kcshyan is offline kcshyan  Malaysia
diyAudio Member
 
Join Date: Sep 2005
yes. dc20v for c3m heater
  Reply With Quote
Old 19th September 2012, 12:35 PM   #19
euro21 is offline euro21  Hungary
diyAudio Member
 
Join Date: Sep 2004
Location: Budapest
3.1V on the 1K cathode resistor = 3.1mA current.
C3m unhappy with this low current, 16-30mA is optimal.

C3m datasheet:
if tube saturated (?) - 10V anode-cathode - anode current apx. 10mA, independently of the grid (G1) voltage.

I think this tube have misconnected pins.
  Reply With Quote
Old 19th September 2012, 03:01 PM   #20
diyAudio Member
 
Join Date: Oct 2002
Location: SINGAPORE
Quote:
Originally Posted by euro21 View Post
3.1V on the 1K cathode resistor = 3.1mA current.
C3m unhappy with this low current, 16-30mA is optimal.

C3m datasheet:
if tube saturated (?) - 10V anode-cathode - anode current apx. 10mA, independently of the grid (G1) voltage.

I think this tube have misconnected pins.
16-30mA? that would be optimal in triode mode.
i am also suspecting wrong connections, especially the pin orientations.
but only if there is a picture, then we can tell.

Last edited by commstech; 19th September 2012 at 03:03 PM.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Yamamoto A-09s fonnesbek Tubes / Valves 11 22nd November 2012 09:12 AM
300B SE amp: One more one Yvesm Tubes / Valves 15 22nd February 2010 05:12 PM
* 35 watt * 300B SE = super 300B + Class A2 rick57 Tubes / Valves 4 13th July 2005 04:18 PM
My 300b SE amp purer Tubes / Valves 2 28th December 2002 04:25 AM


New To Site? Need Help?

All times are GMT. The time now is 11:40 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2