World-Designs-Forum  

Go Back   World-Designs-Forum > WAD > WAD General
Register FAQ Members List Calendar Gallery Today's Posts Mark Forums Read

WAD General For discussions re World Audio Design

Reply
 
Thread Tools Display Modes
  #1  
Old 5th February 2017, 04:09 PM
yuming916 yuming916 is offline
Junior Member
 
Join Date: Feb 2017
Location: changsha, hunan, china
Posts: 13
Default WAD K5881 Circuit Diagram Needed

Hi, this is my first post here. I recently got a partially built WAD K5881 without
circuit diagram and the Schematics. I believe this is a push pull built. See the attached pictures. Would you please PM me the relevant circuit diagram and the Schematics, and the instruction manuals, so that I could rebuild it? Any suggestion is welcome.
Attached Images
File Type: jpg 02.jpg (91.7 KB, 76 views)
File Type: jpg 01.jpg (85.9 KB, 56 views)
Reply With Quote
  #2  
Old 5th February 2017, 06:23 PM
John Caswell John Caswell is offline
Super Moderator
 
Join Date: Dec 2005
Location: Wokingham, Berkshire
Posts: 1,764
Default Re: WAD K5881 Circuit Diagram Needed

Well therein lies the rub. There were two versions of the 5881 push-pull, one using an EF86 front end and the other using a 7025.
The simplest way to check is to look at the front end valve heater pins.
If ONLY pins 4&5 for the heater wiring are used then it is a Mark I using an EF86. If pins 4&5 are connected together and the heater wiring goes to those two pins and also pin 9 then it is the Mark II using a 7025. Do not confuse the phase splitter valve, an ECC83, with the front end valve look carefully.
Circuit diagram and schematics are two words for the same thing. It is possible that a forum member will have the assembly instructions so ask nicely
If any further help is required, just post here and someone is bound to help you out.

John
Reply With Quote
  #3  
Old 6th February 2017, 02:08 AM
yuming916 yuming916 is offline
Junior Member
 
Join Date: Feb 2017
Location: changsha, hunan, china
Posts: 13
Default Re: WAD K5881 Circuit Diagram Needed

Thank you John.
In fact this kit belongs to a friend of mine and I haven't got this one because of lacking the schematics. From the pictures I got I can judge that this kit is probably Mark II. So I badly need the relevant schematics to rebuild the kit. Also, I have one question to ask, how could one check if those transformers are in good condition before rebuilding?
Sorry, if the front end valve sits in the middle, then it looks like pin4 and 5 are heat pins, then it should be Mark I. I have to confirm it.
Attached Images
File Type: jpg 04.jpg (132.0 KB, 65 views)

Last edited by yuming916; 6th February 2017 at 03:47 AM.
Reply With Quote
  #4  
Old 6th February 2017, 08:54 AM
Wieslaw Lipowski's Avatar
Wieslaw Lipowski Wieslaw Lipowski is offline
Senior Member
 
Join Date: Jan 2006
Location: Warsaw, Poland
Posts: 139
Default Re: WAD K5881 Circuit Diagram Needed

Here is the older schematic.
Attached Images
File Type: jpeg 5881 I.jpeg (141.2 KB, 147 views)
__________________
Wiesiek
Reply With Quote
  #5  
Old 6th February 2017, 09:50 AM
yuming916 yuming916 is offline
Junior Member
 
Join Date: Feb 2017
Location: changsha, hunan, china
Posts: 13
Default Re: WAD K5881 Circuit Diagram Needed

Wiesiek, thank you so much for the diagram and the instructions. Is this a push pull class A circuit?
Reply With Quote
  #6  
Old 6th February 2017, 02:30 PM
Wieslaw Lipowski's Avatar
Wieslaw Lipowski Wieslaw Lipowski is offline
Senior Member
 
Join Date: Jan 2006
Location: Warsaw, Poland
Posts: 139
Default Re: WAD K5881 Circuit Diagram Needed

Push-Pull - yes.

I don't think its' an A class amp, though. It's too strong to be in class A with these valves.
__________________
Wiesiek
Reply With Quote
  #7  
Old 6th February 2017, 02:50 PM
yuming916 yuming916 is offline
Junior Member
 
Join Date: Feb 2017
Location: changsha, hunan, china
Posts: 13
Default Re: WAD K5881 Circuit Diagram Needed

Thanks, Wiesiek。
Can the diagrams be clearer? I can read the instruction without problem. But
to read the numeric values in the diagram correctly is a quite tough job for me.
Reply With Quote
  #8  
Old 8th February 2017, 02:50 PM
Wieslaw Lipowski's Avatar
Wieslaw Lipowski Wieslaw Lipowski is offline
Senior Member
 
Join Date: Jan 2006
Location: Warsaw, Poland
Posts: 139
Default Re: WAD K5881 Circuit Diagram Needed

I also have an MkII schematic. Perhaps you will it useful, too.
Attached Images
File Type: jpg K5881 2.JPG (112.1 KB, 112 views)
__________________
Wiesiek
Reply With Quote
  #9  
Old 8th February 2017, 04:35 PM
yuming916 yuming916 is offline
Junior Member
 
Join Date: Feb 2017
Location: changsha, hunan, china
Posts: 13
Default Re: WAD K5881 Circuit Diagram Needed

Hi Wiesiek, many thanks again.
My friend has sent me the kit, so I'll get it in a couple of days. I heard those kits were constructed by you. That must be a great job.
Judging from the previous pictures, since the output transformer is as tall as the power transformer, I am also thinking that this kit might be the pse one. I googled and found the schematic named wadpse5881. Once I got the kit, I may measure the resistance of the primaries of the output transformer. Since the pse one is 44% U.L. tapped, it would be easy to tell the difference. I just post the third schematic. Can you tell me if this is the correct one?
Attached Images
File Type: jpg wadpse5881.jpg (112.1 KB, 89 views)
Reply With Quote
  #10  
Old 8th February 2017, 09:12 PM
Wieslaw Lipowski's Avatar
Wieslaw Lipowski Wieslaw Lipowski is offline
Senior Member
 
Join Date: Jan 2006
Location: Warsaw, Poland
Posts: 139
Default Re: WAD K5881 Circuit Diagram Needed

Yes, I did build kits KEL 34, KEL80 and KiT88, but not K5881's. However, I did not construct them (I mean - didn't design).

The schematic you posted is of course an SE, not Push-Pull.

Good luck with your project.
__________________
Wiesiek

Last edited by Wieslaw Lipowski; 8th February 2017 at 10:40 PM.
Reply With Quote
Reply

Tags
k5881

Thread Tools
Display Modes

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


All times are GMT +1. The time now is 10:32 AM.


Powered by vBulletin® Version 3.7.3
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Copyright World Designs