Power transformer question
 User Name Stay logged in? Password
 Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read Search

 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
tom42107
Account disabled at member's request

Join Date: Feb 2010
Power transformer question

I have an unknown transformer question. As you can see, the secondary is made up of two yellow, two orange, two red and one black. There is continuity between orange, red and black, not yellow. Voltage readings are:
Yellow - 15v
Orange - 56v
Red - 96v
Assuming the black wire is a center tap, I get ~26v on each orange and ~46v on each red. So, what is the black wire?

Tom
Attached Images
 Transformer.jpg (165.6 KB, 143 views)

glennb
diyAudio Member

Join Date: May 2004
Location: Melbourne
Quote:
 Assuming the black wire is a center tap, I get ~26v on each orange and ~46v on each red. So, what is the black wire?
If you are using a meter with high input resistance you are probably measuring leakage between the windings. I suggest you put a 10K Ohm resistor across the meter probes to shunt away the miniscule leakage currents, and then measure again from black to each of the other secondary wires. If the reading is zero the black is probably an electrostatic shield that should be grounded.
__________________
Glenn.

 20th November 2012, 02:58 AM #3 tom42107   Account disabled at member's request   Join Date: Feb 2010 Glenn, I tried the 10k resistor and it's still the same thing. The black seems to be common to both the red and orange wires. Tom
 20th November 2012, 03:02 AM #4 TonyTecson   diyAudio Moderator     Join Date: May 2003 Location: Palatiw, Pasig City it is the center tap....except that the readings would have been 1/2 of what you measured between red and red and orange and orange.... __________________ planet10 needs your help: Let's help Ruth and Dave...http://www.diyaudio.com/forums/plane...ml#post5010547[B
glennb
diyAudio Member

Join Date: May 2004
Location: Melbourne
Quote:
 Originally Posted by tom42107 Glenn, I tried the 10k resistor and it's still the same thing. The black seems to be common to both the red and orange wires.
OK, it seems one of the windings is red - orange - black - orange - red. ie. 46 Volts aside of the CT, with taps at 26 Volts. From either red, do you read ~20 Volts to one orange and ~72 Volts to the other orange?
__________________
Glenn.

 20th November 2012, 10:23 AM #6 DF96   diyAudio Member   Join Date: May 2007 The orange is probably for powering preamp stages, and the red for power amp of an integrated amp. The yellow does something else - maybe (after regulation) +12V for an FM tuner?
 20th November 2012, 12:17 PM #7 tom42107   Account disabled at member's request   Join Date: Feb 2010 Yes, that's exactly what I get when I measure from any red to the orange wires. I think it may have come out of one of those all-in-one integrated amp things. So, no matter which color I end up using, (red or orange), I should treat the black as a center tap? Last edited by tom42107; 20th November 2012 at 12:27 PM.
glennb
diyAudio Member

Join Date: May 2004
Location: Melbourne
Quote:
 Originally Posted by tom42107 Yes, that's exactly what I get when I measure from any red to the orange wires. I think it may have come out of one of those all-in-one integrated amp things. So, no matter which color I end up using, (red or orange), I should treat the black as a center tap?
Good. Yes, black is CT. Here is an example of generating two different positive DC supplies. Overlay the same design with reversed diodes to add negative supplies, relative to the CT.
Attached Images
 sch1.jpg (13.4 KB, 101 views)
__________________
Glenn.

 21st November 2012, 01:44 PM #9 Robert Kesh   diyAudio Member     Join Date: Oct 2012 The missing 4 volts is kind of curious. I wonder if the centre tap has been back-wound.
 21st November 2012, 05:27 PM #10 DF96   diyAudio Member   Join Date: May 2007 Good point. Maybe the OP can recheck his voltage readings and confirm that the black really is a CT and not offset a little.

 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 Rules
 Forum Jump User Control Panel Private Messages Subscriptions Who's Online Search Forums Forums Home Site     Site Announcements     Forum Problems Amplifiers     Solid State     Pass Labs     Tubes / Valves     Chip Amps     Class D     Power Supplies     Headphone Systems Source & Line     Analogue Source     Analog Line Level     Digital Source     Digital Line Level     PC Based Loudspeakers     Multi-Way     Full Range     Subwoofers     Planars & Exotics Live Sound     PA Systems     Instruments and Amps Design & Build     Parts     Equipment & Tools     Construction Tips     Software Tools General Interest     Car Audio     diyAudio.com Articles     Music     Everything Else Member Areas     Introductions     The Lounge     Clubs & Events     In Memoriam The Moving Image Commercial Sector     Swap Meet     Group Buys     The diyAudio Store     Vendor Forums         Vendor's Bazaar         Sonic Craft         Apex Jr         Audio Sector         Acoustic Fun         Chipamp         DIY HiFi Supply         Elekit         Elektor         Mains Cables R Us         Parts Connexion         Planet 10 hifi         Quanghao Audio Design         Siliconray Online Electronics Store         Tubelab     Manufacturers         AKSA         Audio Poutine         Musicaltech         Holton Precision Audio         CSS         Dx Classic Amplifiers         exaDevices         Feastrex         GedLee         Head 'n' HiFi - Walter         Heatsink USA         miniDSP         SITO Audio         Twin Audio         Twisted Pear         Wild Burro Audio

 Similar Threads Thread Thread Starter Forum Replies Last Post SparkyPete Tubes / Valves 10 2nd November 2012 06:13 PM tom42107 Power Supplies 3 6th August 2012 06:28 PM srinath Power Supplies 6 10th June 2012 02:07 PM woodturner-fran Tubes / Valves 6 9th March 2011 11:04 PM i_drives Parts 1 25th November 2003 12:53 AM

 New To Site? Need Help?

All times are GMT. The time now is 08:01 AM.