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Hi All,
I have a question regarding the 6.3 heater connections to the PCB terminal.

My brand new XPWR005 has two yellow and two brown wires for the 6.3 volt taps (note this is different colors than was is referred to in the manual).

Do I wire one yellow and one brown to pin 7 and one yellow and brown to pin 8 OR two yellows to pin 7 and two browns to pin 8?

I am also using these taps to power some LEDS (via bridge rectifier/cap) and I did a quick power check (with the yellow/brown to same pin) and it seems it is not working... retested circuit with battery DC and LEDs still work... already glued 3mm led to socket holes and was glad I didn't burn them out.

Haven't received tubes yet so I haven't had any other issues- but this make me question this -as typical i only have used one set of heater taps in the past.

Thanks for the help.

like the picture ... you need to QUICKLY test the phasing to make sure you have 6.3 or so volts
if you're out of phase you might have zero ... tap QUICKLY while watching a voltmeter.
if it's not right, reverse one of the pairs.

The method I use is to set your DMM to VAC, apply power to the transformer unloaded, and match a yellow & brown that read ~0VAC (i.e. are in phase). And if one pair reads 0VAC, then the other will as well. Don't match yellow & brown up if they read ~6.6VAC.

You can use my method combined with Tom's. Match the first pair at 0VAC, and then verify with a fast 'tap' of the second pair.

Why does the spark occur? If we wire them incorrectly the filaments are loaded in a loop, loading one another.

Shannon

Thanks for the advice TOM!
After posting -I notice my fuse had been toasted-so I have to get another pack of fuses from RS today.
Would the wrong phasing caused the fuse to blow? I will flip my yellow wires and try again- still a yellow/brown combo like I had and your photo shows.
I also thought more about powering scheme for LEDS - since we have artificial CT for heaters- should I power off one pin/leg and ground instead of pin 7 & pin 8?
Thanks

Wrong phasing of the two 6VAC filament windings, connected in parallel, would cause the fuse to blow, as it would be behaving as a 12VAC winding, shorted out.

/ed B

Thanks all!
swapped the wires and all is good so far - needs to order tubes next week...
Shannon-I would kindly suggest you add your phase tip to the bullets points of the manual.

MacL wrote:Shannon-I would kindly suggest you add your phase tip to the bullets points of the manual.

I think a little YouTube video would hit the mark, too. I've put it on my "to do" list.

Shannon