Go Back   Home > Forums > > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Tubelab Discussion and support of Tubelab products, prototypes and experiments

Reply
 
Thread Tools Search this Thread
Old 1st October 2019, 11:58 AM   #721
audiojunky is offline audiojunky
diyAudio Member
 
Join Date: May 2017
Default spp help

I need help with my spp Im not a total novice Ive made at least 10 guitar amps ranging from marshalla to fenders to matchless all point to point made my own turret boards , this is my first stereo with a pcb thought it would be pretty straight forward but I cant seem to get it sorted I can just hear a signal if I put my ear to the speaker Ive Pulled the board checked all components my voltages seem okay its doing my head in.Ive traced a signal all the way thru to the primary out but when it comes back from the output tranny secondary its quieter than going in
  Reply With Quote
Old 3rd October 2019, 02:29 PM   #722
Duke58 is offline Duke58  United States
diyAudio Member
 
Join Date: Jan 2009
Properly punctuated English translation: (This is what happens when I wake up at 4:00 AM, read the online newspaper and check DIY Audio afterwards. I read your post and thought it was because I'm groggy and haven't had my coffee. Promise though, starting tonight, I'll try and stay up later so I don't wake up so early. Thought to myself, self, with this translation, maybe someone on the forum can help this person out.)

I need help with my SPP. I'm not a total novice, I've made at least 10 guitar amps ranging from Marshall to Fender's to Matchless- all point to point. I also made my own turret boards. This is my first stereo with a PCB. Thought it would be pretty straight forward, but I can't seem to get it sorted.

I can just hear a signal if I put my ear to the speaker. I've pulled the board, checked all components. My voltages seem okay. It's doing my head in. I've traced a signal all the way thru to the primary out, but when it comes back from the output tranny secondary, it's quieter than going in.

(I'm also not sure what a output tranny secondary is? Do you mean the signal from the anode to the input of the output transformer is higher than on the output of the transformer, where the speakers are connected? This mixes me up more than a feather in a whirlwind).
  Reply With Quote
Old 3rd October 2019, 02:35 PM   #723
Tubelab_com is offline Tubelab_com  United States
diyAudio Member
 
Tubelab_com's Avatar
 
Join Date: Jul 2005
Location: West Virginia panhandle
I recently returned from a 2700 mile road trip which involved periods of poor, or no internet availability. I received the same question by email, and a day later another email stating that it had been fixed, and was a grounding problem. My guess is a short across the OPT secondary.
__________________
Tubelab, it's 5 year mission. To explore strange new tubes, to seek out new circuits and topologies, to boldly go where no tube has gone before......
  Reply With Quote
Old 3rd October 2019, 02:43 PM   #724
Duke58 is offline Duke58  United States
diyAudio Member
 
Join Date: Jan 2009
Mr. Tubelab,

Thank you for clarifying that.

If there's one thing in this world that I hate more, it's when a series of long posts are never concluded, a solution isn't provided. It's like never having closure when a relationship goes bad, or watching a foreign movie with a sad ending.
  Reply With Quote
Old 4th October 2019, 12:28 AM   #725
audiojunky is offline audiojunky
diyAudio Member
 
Join Date: May 2017
Sorry guys yeah i let george know but forgot about diy. Yeah it was a short from the output transformer, its always something really simple.and sorry about my aussie slang and bad gramma , my wifes always having a go at me about that
  Reply With Quote
Old 10th October 2019, 01:57 PM   #726
Francois G is offline Francois G  United States
diyAudio Member
 
Join Date: Jun 2004
Location: Illinois
Quote:
Originally Posted by audiojunky View Post
.....sorry about my aussie slang and bad gramma .....
Oh dear, sorry to hear about your bad Gramma .... mine is the sweetest little-old-lady you ever met😄
  Reply With Quote
Old 4th November 2019, 09:35 PM   #727
Skorpio is offline Skorpio  Denmark
diyAudio Member
 
Join Date: Mar 2004
Location: Denmark
A diode or a lamp is often placed between the grid and the cathode of the phaseinverter, to prevent arcing at start-up.

Is this not needed here?
  Reply With Quote
Old 4th November 2019, 10:17 PM   #728
Tubelab_com is offline Tubelab_com  United States
diyAudio Member
 
Tubelab_com's Avatar
 
Join Date: Jul 2005
Location: West Virginia panhandle
In some circuits there is a potential for large current flow, and some protection is a good idea.

Here there could be a possibility for 4 mA or so (B+/100K resistance) to flow from grid to cathode in the 12AT7 if the rectifier conducts before the 12AT7 does.

Worse case is a 6CW5 amp with a solid state rectifier, since B+ is instant. The cathode of a 12AT7 can support well over 10 mA in normal operation, so it's not harmed at 4 mA. A positive grid will conduct, keeping the grid voltage low, 10 volts or so. This keeps the grid dissipation well below 100 milliwatts during the short time that this is happening.
__________________
Tubelab, it's 5 year mission. To explore strange new tubes, to seek out new circuits and topologies, to boldly go where no tube has gone before......
  Reply With Quote

Reply


Tubelab Simple P-PHide 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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Electrolyticless Tubelab Simple SE nic6paul Tubelab 26 20th August 2013 01:56 PM
Second Tubelab Simple SE board done budmaestro Tubelab 0 24th July 2008 01:18 AM
First Project Finished-Tubelab Simple SE waam68 Tubelab 2 12th April 2008 07:23 AM
Tubelab Simple SE & Edcor waam68 Tubelab 2 6th March 2008 01:15 PM
New SET: JE labs simple 45 or tubelab SE? cwujek Tubelab 14 27th November 2007 05:15 AM


New To Site? Need Help?

All times are GMT. The time now is 04:57 PM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.00%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Copyright ©1999-2019 diyAudio
Wiki