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new edcor transformer help (Read 6422 times)
coopercustoms
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new edcor transformer help
10/27/11 at 00:19:56
 
I'm new to this and just need someone to hold my hand. The new edcor transformers have different color wires than are silkscreened on the board. The updated schematic helps a little but I would really like a clear translation between the new wire colors and what is on the circut board. Thanks for any help.
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Kaloyanr
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Re: new edcor transformer help
Reply #1 - 10/27/11 at 01:48:39
 
me too I need some info for this.

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dank
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pair of dual 18
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Re: new edcor transformer help
Reply #2 - 10/27/11 at 17:32:07
 
You need to identify the two primary wires (they go to B+ and the tube plate) and the secondary wires (they go to the speaker).  With a DVM (digital volt/ohm meter - digital multimeter) measure the 4 wires.  The two that read just a couple of ohms are the secondary, and the two that read a few hundred ohms are the primary.  If you don't have a DVM, buy one...you have no business building a Zkit1 without one.  The cheapest DVM you can find, even the $2 one, when on sale at Harbor Freight, will be plenty good enough.  As far as phase and +/- go, usually the + is a color and the - is black or white.  Red is almost always +, black is almost always -.  For sure, hook up both transformers the same way and you can't go too far wrong.

Dan
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coopercustoms
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Re: new edcor transformer help
Reply #3 - 10/27/11 at 18:18:53
 
thanks. i do have a meter and i do know the values of the leads coming from the transformers. output transformers make sense with the exception of the screen wire. does this go to the board? it's the power transformer I need the most help with. primary is easy. secondary is a little confusing.
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dank
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pair of dual 18
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Re: new edcor transformer help
Reply #4 - 10/28/11 at 14:38:42
 
Output transformer screen wire (if it has one) will not be used.

Power transformer 240 v:  primary (black/black) goes to switched, fused 220-240 vac.  yellow & yellow 5vac secondary is not used, just as the yel & yel with yel/wht on the schematic is not used.  Brown & brown 6.3 vac secondary goes to the tube heaters - there is no center tap wire on this coil, so there will be no wire to solder to the gnd spot on the Zkit1 circuit board.  Red & red with black/red centertap is the high voltage secondary that should correspond to the same colored wires on the schematic.

Power transformer 120 v:  identical to 240 vac except there is no (unused) 5vac secondary winding and it connects to switched, fused, 120vac.

Dan
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coopercustoms
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Re: new edcor transformer help
Reply #5 - 10/28/11 at 16:11:59
 
thanks, that makes sense.
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Kaloyanr
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Re: new edcor transformer help
Reply #6 - 11/01/11 at 03:11:44
 
Yes, new colour wires:

The output transformer, why it has a white / blue screen, which is not used?











Did I put them right on the scheme?



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« Last Edit: 11/01/11 at 21:13:33 by Kaloyanr »  
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Kaloyanr
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Re: new edcor transformer help
Reply #7 - 12/03/11 at 16:00:51
 
Something important!
The new transformer missing GND wire from heating (two new brown wire)
In the old they were greens and  there had one to GND (grn/yel), now missing!
I had an unpleasant noise, I just put an extra wire from one brown end  to GND and the noise disappeared almost.
I do not know how to properly Steve has to say. May be have to use 2 resistors 100 Ohm from each end, or ?!



Regards
Kaloyan
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« Last Edit: 12/03/11 at 20:55:50 by Kaloyanr »  
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mboxler
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Re: new edcor transformer help
Reply #8 - 05/31/12 at 16:03:52
 
Kaloyanr...

First post, as I just purchased the ZKIT1 (board only).  Have you completed your build, and if so, can you provide pictures of the transformer connections to the board?  Edcor wire colors concern me, and I'd feel more comfortable with a picture before I begin.

Thanks, Mike
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« Last Edit: 05/31/12 at 19:04:37 by mboxler »  
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patrick
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Re: new edcor transformer help
Reply #9 - 08/20/12 at 00:22:54
 
Hi, I am totally stumped. Can some one please tell me where the brown wires from the Edcor XPWR107-120 are supposed to connect to the SE84C board?
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mboxler
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Re: new edcor transformer help
Reply #10 - 08/20/12 at 14:29:28
 
Hi patrick

I assume you have the REV 9 2011 PCB.  The brown wires are used to heat the tubes.  Solder them to the holes marked GRN (you will notice they run to pins 4 and 5 on all three tubes).  Steve has recently modified the board to match the colors of the EDCOR transformers.

His revision also talks about creating an artificial center tap for the brown wires.  I haven't tried it yet, but it required two 100 ohm resistors running from each GRN hole to ground (I plan on using the GRN/YL, which would have been the connection if the brown wires were center tapped).  This mod is supposed to reduce the hum you will hear from the tubes when you light them up.

Hope this helps.

Mike

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« Last Edit: 08/20/12 at 15:42:17 by mboxler »  
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patrick
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Re: new edcor transformer help
Reply #11 - 08/22/12 at 02:42:40
 
Thanks!
I actually figured it out after writing this post. I just looking at the schematic and after adout two hours the light went off!
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patrick
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Re: new edcor transformer help
Reply #12 - 08/27/12 at 00:58:27
 
Hi
What does it mean when the speaker binding post register 450+ vdc when the amp is powered up? I don't think this is nornal.
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mboxler
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Re: new edcor transformer help
Reply #13 - 08/27/12 at 02:56:08
 
Hi Patrick...

I'm no expert (someone please correct me if I'm wrong).

Speakers require alternating current.  

A tube is a high-voltage/low-current (high-impedance) device, while a speaker is a low-voltage/high-current (low-impedance) device. The function of the audio output transformer is to transform the high impedance of the output tube to match the much lower impedance of the speaker. This is necessary to get an efficient transfer of the audio signal to the speaker.  (I copied this from an article, so I hope it's true).

I think you are getting a false number when you are using the DC voltage setting on your meter.

What were your other test point voltages (they are DC)?  If they are okay, then you should be good to go.

Mike
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« Last Edit: 08/27/12 at 03:15:33 by mboxler »  
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patrick
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Re: new edcor transformer help
Reply #14 - 08/27/12 at 03:20:05
 
Hi Mike,
Point A is abot 450, point B 309, point C and D are both OK though.  To test the speaker terminals, I kept the voltmeter settings the same after testing A, and the measurements were the same as with A. I have the board in a wood enclousure atop atravertine tile. I have the amp grounded with a grounded cord using the sheild ground from the board. I know I have done something wrong - just not sure where. The tubes light up and there isn't any smoke, just very high voltage!
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