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.

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

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

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?

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

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

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.

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!

Hi Mike,
Your help was invaluable, thanks! After reading your post, I rewired the two amps and like magic the darn thing worked! It sounds great paired with my vintage Infinity RS6001s. Now to convince my wife that I need more effecient speakers! Wish me luck.

Congratulations!  I'm not sure how I helped, but....

I keep trying to work on mine, but life keeps getting into the way!  I'll be driving a pair of Klipschorn's (at 104 dB sensitivity, should be plenty of power).  I also have a pair of Klipsch RF-83's.  Should be fun.

If you like DIY, there are some neat single driver kits that would be fun to build!  Great imaging!  Great Christmas gift from your wife!

Best, Mike