[leitmo]

hi everyone!

last weekend i finished my first cornet 2, i'll describe the final steps of the building:

- AC is 222 VAC so i decided to connect 370BX transformer to 220V, correct?
- transformer is not connected to ground PCB or binding post
- i installed a slo-blow fuse 0'5A
- i used metal standoffs not connected to ground binding post
- Earth from IEC connected to ground binding post
- PCB Earth quick release terminal connected to ground binding post
- RCA in&out ground (not the tip, the ring) connected to ground binding post

I switched ON, no smoke, no burning, RED LED turned GREEN in 5-8 seconds then:
-12AX7 (both are Sovtek) and 5Y3GT (TAD) started glowing, very nice
-12AU7 did not glow as much as other tubes, only a few

i measured voltages on PCB and i found the next image

http://www.audiocircle.com/index.php?action=gallerylastup&cat=0&pos=0

i found it strange (values marked as 1) so i change the position of the 12AX7, the first stage tube put it on the second one and viceversa and i measured voltages (values marked as 2)

sorry because my english is not very charming, so if you don't understand something i'll explain it again

Can anybody tell me what's wrong?

may be 12AU7, may be some cap or resistor?

i double checked my work but i'll do it again to be sure is not my mistake

Thanks everyone!!!

[leitmo]

Sorry, it's the first time i post an image, this is what i found when i measured voltages on PCB

http://www.audiocircle.com/index.php?action=gallerysearch&cat=0&pos=0

Thanks for the help!!!

[leitmo]

sorry everybody who has read this post, i've finally discovered how to post an image, i hope yo can see it now:




i marked with number 1 the voltage values with the first tubes position

i marked with number 2 the voltage values changing 12AX7 of the first stage by the 12AX7 of the second stage

PS: i've connected my turntable and no noise, no hum and no music were at the output

thanks everyone for the patient!!!

[hagtech]

I think you got some resistor values in the wrong place.  Left channel not too bad, right is really messed up.  Are you sure the tubes are good?  What is heater voltage?  Did you use the correct transistors in the current sinks?  Yeah, probably something like using 220k ohm instead of 220 ohm. 

jh

[leitmo]

thanks Jim!

a double check is not always enough.
I'll look for the mistake this weekend.
Tubes are all new

I'll post as soon as i have news

Thanks again!

[hagtech]

Yeah, I suspect a wrong resistor.  New tubes are no guarantee they are working.

jh

[leitmo]

Hi Jim!

I've just done half of the work, all components are where they are supposed to be (looking at the user's manual then compare the resistor color code),

now i'm unsoldering  to check them individually. Capacitors are OK (i only measured less than 2uF caps, my Cap Tester doesn't support higher capacitance). I have resoldered tube sockets.

Tomorrow will check Resistors

Heater voltage is measured in the tube center hole, isn't it? it's 5'79VDC. It's ok?

Thanks for all Jim!