5F2-A bad harmonic and distortion

Ibchez · 07-14-2009, 07:57 AM

Greetings to everyone, this is my first post and my first build. I´m an American living in Spain. I have built a 5F2-A using Steve Milberger´s schematic and layout. I made an error when I wired up the PT basically applying 220v to a 110 wired circuit. PT died on the spot. I obtained a new one and wired it correctly and the amp now amplifies but there is unpleasant distortion and a weird sci-fi sounding out-of-tune harmony accompanying the notes. I fear I have damaged some components with excessive voltage. Can anyone advise me on how to proceed?

Chuck H · 07-14-2009, 08:16 AM

Wow... With that set up, it could be a lot of things. I'll bet there's a mistake in the wiring. But it could also be bad filter caps. If the high voltage damaged your filters you would have a second oscillating note riding on top of the basic tone. You would also have excessive hum.

Chuck

MWJB · 07-14-2009, 11:07 AM

Could have blown the OT too, pull the power tube and measure ohms from 6V6 pin 3 to hot terminal of first filter cap after the rectifier.

Ibchez · 07-14-2009, 01:08 PM

Thanks for your reply. Pin three to the first filter cap reads 220 ohms. I don´t know how to test the caps but I have ordered new tubes and caps.

MWJB · 07-14-2009, 01:12 PM

220ohms seems about ball park, OT should be OK.

Ibchez · 07-14-2009, 01:22 PM

So my plan from here is double check all wiring, swap out tubes, and replace filter caps. Any other suggestions?

07-14-2009, 07:57 AM	#1
Ibchez Junior Member Join Date: Jul 2009 Location: Benalmadena Spain Posts: 3	5F2-A bad harmonic and distortion Greetings to everyone, this is my first post and my first build. I´m an American living in Spain. I have built a 5F2-A using Steve Milberger´s schematic and layout. I made an error when I wired up the PT basically applying 220v to a 110 wired circuit. PT died on the spot. I obtained a new one and wired it correctly and the amp now amplifies but there is unpleasant distortion and a weird sci-fi sounding out-of-tune harmony accompanying the notes. I fear I have damaged some components with excessive voltage. Can anyone advise me on how to proceed?

07-14-2009, 01:08 PM	#4
Ibchez Junior Member Join Date: Jul 2009 Location: Benalmadena Spain Posts: 3	pin three ohms Thanks for your reply. Pin three to the first filter cap reads 220 ohms. I don´t know how to test the caps but I have ordered new tubes and caps.

07-14-2009, 01:22 PM	#6
Ibchez Junior Member Join Date: Jul 2009 Location: Benalmadena Spain Posts: 3	Next step So my plan from here is double check all wiring, swap out tubes, and replace filter caps. Any other suggestions?

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07-14-2009, 08:16 AM	#2
Chuck H Old Timer Join Date: May 2007 Location: pacific north west Posts: 1,482	Wow... With that set up, it could be a lot of things. I'll bet there's a mistake in the wiring. But it could also be bad filter caps. If the high voltage damaged your filters you would have a second oscillating note riding on top of the basic tone. You would also have excessive hum. Chuck

07-14-2009, 11:07 AM	#3
MWJB Old Timer Join Date: Jun 2006 Posts: 1,926	Could have blown the OT too, pull the power tube and measure ohms from 6V6 pin 3 to hot terminal of first filter cap after the rectifier.

07-14-2009, 01:12 PM	#5
MWJB Old Timer Join Date: Jun 2006 Posts: 1,926	220ohms seems about ball park, OT should be OK.

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