Audio Asylum Thread Printer

Get a view of an entire thread on one page

FAQ / News / Events

OTL Asylum

Novacron problem

68.12.184.33

rhinohifi714

I recently purchased a pair of Novacron's
within a few hours of the initial listen I noticed both amps were distorting so I powered them down and found that one fuse had blown in one amp the other didn't blow any fuses.
I did find that one of the 12at7's was bad and one of the 6c33c's was nearly dead. I replaced both and proceeded to warm up and re-bias and set the dc offset.
as soon as I flipped the switch up to play it started making noise to the speaker which I thought was strange since the positive that goes to the speaker was inserted in the test banana, anyway while noise was going on I was able to get the idle current up to the rated 350ma but when checking the dc offset it was pegged to the left and with full rotation of the pot the needle never attempted to move from pegged to the left, I turned it off and have not done anything else.
does anyone have a suggestion ?
I'm for some reason thinking a capacitor or diode but have not got it to the bench yet.
any help or suggestions would be greatly appreciated.

Edits: 12/07/24

Follow Ups:

Make sure all your fuses are good. - Ralph 10:41:27 12/10/24 (2)
Novacrons all have a fuse for each power tube. The original run with 2 controls (Bias and DC Offset) have the fuses beneath the bottom cover.

That was inconvenient! We later moved the output tube fuses to the rear panel. Novacrons that are set up this way have a total of 7 fuses on the rear panel as a result; 3 on one side of the IEC connector and 4 on the other side. Obviously the 3 on one side are not fuses for the tubes.

If a tube fuse blew, you won't be able to balance the meter, and from your description it sounds like you have a later Novacron with 4 bias controls in front of the driver tubes.
- Ralph, your stuff is consistently beautiful (nt) - Chip647 15:19:23 12/21/24 (0)
- RE: Make sure all your fuses are good. - rhinohifi714 11:50:26 12/10/24 (0)
  Ralph thanks for your reply,
  
  My friend built these when you offered them as a kit.
  He passed away last year and I was able to get them from
  the estate.
  
  the amps do have 7 fuses on the back
  
  but only a single dc offset adjust and another for bias in front of
  the 4 12at7's

Post a Followup:

FAQ

Post a Message!

Forgot Password?

Moniker (Username):
Password (Optional):
	Remember my Moniker & Password (What's this?) Eat Me
E-Mail (Optional):
Subject:

Message:	(Posts are subject to Content Rules)

Optional Link URL:
Optional Link Title:
Optional Image URL:
Upload Image:
E-mail Replies:	Automagically notify you when someone responds.

To view your new posting or follow-up, click on the RELOAD or REFRESH button on your browser.

This post is made possible by the generous support of people like you and our sponsors: