A heater wiring DOH! moment??

maynardg · 3rd March 2007, 08:36 PM

Hello Folks. I am working on a new SE amp. Problems with the 6.3V heaters. I measure 3.2V at each pin (both socket and pin). Neither the 6SJ7's nor the KT88's heat up. What is my DOH??

Should I be grounding the CT or should it float?

w5jag · 3rd March 2007, 09:23 PM

You didn't by chance use the 230V primary on a 230/115V dual primary transformer, did you?

I would think you would want the center tap grounded, but just disconnect your filament string from the transformer, ground the center tap, and see if that gives you the voltage you expect.

Win W5JAG

maynardg · 3rd March 2007, 09:45 PM

I have the 5V rectifier and B+ I expect. The 6.3V heaters are CT and the CT is grounded.

I think perhaps I have a faulty heater supply. One lead reads 3.2V, the other .33V referenced to ground.

Darn.

Zibi · 4th March 2007, 09:27 AM

If the transformer is good, one of the filament wire is probably shorted to the ground.

Alastair E · 4th March 2007, 10:31 AM

Sounds to me like the centre-tap is wired out of phase, IF you measure 3.2V at each heater pin with the ct earthed.........

reverse one half of the 6.3V secondary heater winding, and all should be well....

3rd March 2007, 08:36 PM	#1
maynardg diyAudio Member Join Date: May 2003 Location: FL	A heater wiring DOH! moment?? Hello Folks. I am working on a new SE amp. Problems with the 6.3V heaters. I measure 3.2V at each pin (both socket and pin). Neither the 6SJ7's nor the KT88's heat up. What is my DOH?? Should I be grounding the CT or should it float? __________________ MG

3rd March 2007, 09:45 PM	#3
maynardg diyAudio Member Join Date: May 2003 Location: FL	I have the 5V rectifier and B+ I expect. The 6.3V heaters are CT and the CT is grounded. I think perhaps I have a faulty heater supply. One lead reads 3.2V, the other .33V referenced to ground. Darn. __________________ MG

4th March 2007, 10:31 AM	#5
Alastair E diyAudio Member Join Date: Feb 2004 Location: South Wales	Sounds to me like the centre-tap is wired out of phase, IF you measure 3.2V at each heater pin with the ct earthed......... reverse one half of the 6.3V secondary heater winding, and all should be well.... __________________ Das Beste Oder Nichts

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Heater wiring help!	losacco	Tubes / Valves	1	23rd May 2009 08:33 PM
1st Project Heater Wiring	cgrums	Tubes / Valves	14	24th August 2007 07:03 PM
!2ax7 heater wiring? Series / parallel?	glaznost45	Tubes / Valves	1	27th February 2006 11:51 AM
heater wiring	tenderland	Tubes / Valves	6	2nd March 2005 08:14 PM

3rd March 2007, 09:23 PM	#2
w5jag diyAudio Member Join Date: Feb 2007 Location: Arkansas	You didn't by chance use the 230V primary on a 230/115V dual primary transformer, did you? I would think you would want the center tap grounded, but just disconnect your filament string from the transformer, ground the center tap, and see if that gives you the voltage you expect. Win W5JAG

4th March 2007, 09:27 AM	#4
Zibi diyAudio Member Join Date: Jan 2006 Location: Bialystok	If the transformer is good, one of the filament wire is probably shorted to the ground.

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read