Motorboating---Help Please!!

[Qpiter]

I built Leak TL/50 Plus from scratch ,point to point. The only thing I changed
is the layout: Kt88, EF86, 12ax7 KT88 in that order. All voltages appears fine.
The amp is playing wonderful untill I connect the Feedback. Then it started motorboating at a rapid pace. OK I know for sure that is connected right. It's
Edor transformer and it was in another amp. I tried many resistor but it only
stop if I use like 1 or 2 megs.
OK, I am a dilettante and I am working with only a mulitimeter. Any help or
suggestions will be appreciated.http://44bx.com/leak/Leak/Circuits/tl50_ecc83.JPG

 

[audiowize]

Switch the secondary connections around and try it that way just to be sure.

 

[rayma]

The primary of the output transformer could be wired wrong; that is,
the upper tube to the lower taps, and the lower tube to the upper taps.
No doubt the secondary is wired ok though.

 

[Ryssen]

I just had this problem on a kt77 P-P amp.
I switched the polarity on the secondare and it was solved.
Try it.

 

[rayma]

The secondary has an 8 ohm tap and is not symmetrical. It would be symmetrical if there were
only 4 and 16 ohm taps. Here it is not appropriate to switch the 0 and 16 ohm secondary connections.

As an alternative to rewiring the output transformer primary, instead you could exchange the driver
connections to the grids of the output tubes.

 

[Qpiter]

Wow! I am so happy. I don't know if you guys understand how valuable your help is;how
much it is appreciated. Rayma, your are the champ! I did exactly as you stated and there
is no more motorboating. How sweet it is not to hear it.Thank you, thank you and thank
you a million times.