DIY Audio Projects Forum
 NEW  Matt presents bias and operation data for the 6V6 tube in SE operation - 6V6 Single-Ended (SE) Ultra Linear (UL) Bias Optimization.

DIY Audio Projects Forum

Welcome to the DIY Audio Projects Message Forum. Use these forums to discuss Hi-Fi audio and to share your DIY Audio Projects. Registration is free and required to post messages and view the file attachments. Registration will only take a minute and registered users do not see any advertisements. After you have completed the online registration process, check your email (including spam/junk folder) for the verification email to activate your account. New members are under moderation - so your posts will not be visible until approved by a moderator. See the Read Me 1st, Forum RULES and Forum FAQ to get started on the forum.

It is currently 23 Jul 2019, 16:07

All times are UTC - 6 hours [ DST ]




Post new topic Reply to topic  [ 7 posts ] 
Author Message
PostPosted: 26 Jan 2009, 18:27 
Offline

Joined: 04 Oct 2008, 11:29
Posts: 375
Location: Chillicothe, Ohio
Hello all, I need some help. I have gotten myself sidetracked away from other projects and I'm going through a 1960 Silvertone Model 29.I'm replacing caps, resistors, etc., that need to be, and the power transformer is caput. I have a Sams Photofact Folder for the amp, which includes the schematic and every part that is in the amp. The parts list simply shows a Silvertone power transformer #46070-3. It is 117V@ .85A on the primary, and 125V@ .570A and 6.3V@ 4.1A on the secondaries. No CTs. Can someone steer me to a good replacement? No luck finding any kind of cross reference and I'm not that experienced selecting transformers. A Google search for that specific Silvertone number got nothing.

Thanks, Greg


Top
 Profile  
 
PostPosted: 26 Jan 2009, 22:00 
Offline
Editor
User avatar

Joined: 28 May 2008, 21:53
Posts: 4577
Location: Winnipeg, CANADA
Hi Greg, I looked at the Hammond catalog and no luck for a HV + Filament transformer with those ratings in one unit. That is a good sized transformer.

_________________
[ DIY Mains AC Power Cable Cord ] - [ Gobo LM1875 Amp Kit ] - [ Tang Band D4-1 Horn Speaker Kit ] - [ Monoblock Push-Pull KT88 Tube Amp Kit ]


Top
 Profile  
 
PostPosted: 27 Jan 2009, 05:06 
Offline

Joined: 04 Oct 2008, 11:29
Posts: 375
Location: Chillicothe, Ohio
Thanks, Gio.

I have several 6.3V filament transformers I can use if need be. I also have an old Stancor with the correct output, but at .25A instead of .570A. I have room to use separate if it comes to that.

Does it seem like overkill on that power transformer? This amp is a push pull using 2 pair of EL84s, a pair of 7199s, and a 12AX7. It's rated at 10 watts per channel.

Thanks, Greg


Top
 Profile  
 
PostPosted: 27 Jan 2009, 13:33 
Offline
Editor
User avatar

Joined: 28 May 2008, 21:53
Posts: 4577
Location: Winnipeg, CANADA
That does seem high.

  • Under 100mA for each push-pull pair
  • perhaps 5 mA for the 12AX7
  • and max 20mA for each 7199

Add some for losses and you would think that 300 mA would be plenty. Are you sure it is 125VAC on the secondary? That seems low for use with those tubes.

_________________
[ DIY Mains AC Power Cable Cord ] - [ Gobo LM1875 Amp Kit ] - [ Tang Band D4-1 Horn Speaker Kit ] - [ Monoblock Push-Pull KT88 Tube Amp Kit ]


Top
 Profile  
 
PostPosted: 27 Jan 2009, 18:10 
Offline

Joined: 04 Oct 2008, 11:29
Posts: 375
Location: Chillicothe, Ohio
Gio,

According to the schematic, 125V in and three outputs from the PSU. 195V, 320V, and 330V. There is actually 325V on the plate of the EL84s, 160V on the pentode plate and 30V on the triode plate of left channel 7199, 150V on the pentode plate and 40V on the triode plate of right channel 7199, and 90V on each plate of the 12AX7.

All values measured from socket pin to common negative with all controls at minimum and proper output load connected.

I could come up with an totally different PSU, I suppose, but don't really want to go to that much trouble if I don't have to.

Thanks, Greg


Top
 Profile  
 
PostPosted: 27 Jan 2009, 18:41 
Offline
Editor
User avatar

Joined: 28 May 2008, 21:53
Posts: 4577
Location: Winnipeg, CANADA
Ok, initially you had mentioned 125V secondary.

I doubt you will be able to find something that will have those secondaries so you will have to make some changes to the power supply. Best best may be a single 250VAC secondary to feed everything and resistors as required to get the right voltages.

_________________
[ DIY Mains AC Power Cable Cord ] - [ Gobo LM1875 Amp Kit ] - [ Tang Band D4-1 Horn Speaker Kit ] - [ Monoblock Push-Pull KT88 Tube Amp Kit ]


Top
 Profile  
 
PostPosted: 27 Jan 2009, 19:04 
Offline

Joined: 04 Oct 2008, 11:29
Posts: 375
Location: Chillicothe, Ohio
I worded my reply incorrectly.

There is a 125VAC secondary from the transformer into the power supply circuit that results in the three outputs I mentioned before.


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 7 posts ] 

All times are UTC - 6 hours [ DST ]


Who is online

Users browsing this forum: No registered users and 2 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Jump to:  
DIY Tube Projects :: DIY Tube Amp Kits :: DIY Speaker Projects :: DIY Solid State Projects :: DIY IC / Op-amp Projects :: DIY Phono Projects :: DIY Cable Projects :: Hi-Fi Audio Schematics
© diyAudioProjects.com - Terms of Service - Privacy Policy