[nocoastjazz]

Here is my aesthetic take on the Cornet.  I used a vintage, wood LP box, cut off the bottom 1/3 of the bottom, flipped it over and painted it black to make a Cornet2 type chassis!

Greetings!  Longtime lurker and first time poster.

I obtained what I thought was a Cornet pcb from a friend and proceeded to order all of the parts for the Cornet kit.  My friend did most of the pcb assembly including the resistors and caps.  I soldered on a few tube sockets, connected the RCAs, and transformer.





My question is that I thought this was a Cornet as the pcb layout looks exactly as the image provided in the Cornet manual. 

However, the pcb clearly reflects a "5Y3" for the rectifier tube.  The 5Y3 is used on the Cornet2.  The 5AR4 is used on the Cornet. 





I stopped myself from using the 5AR4 because of this and plugged in a 5Y3.  My Cornet as is produces glorious sound, no hum - but only from the left side

I swapped out all of the tubes one at a time with no difference.  I swapped the interconnects and the channel being out would switch from right to left.  So I believe I eliminated the interconnects or tubes as the culprits.  I also reconnected my Wright phono stage and have been playing LPs so its not the rest of my system.

Big question - did I overthink and wrongly use the 5Y3 tube and instead should have used the 5AR4 tube because that is what the rest of the layout supports?  The pcb has "C-02 06 04" in the lower, left corner, which I took to mean cornet version 2, June 2004.





However, the upper, right corner simply reflects Cornet Phono Stage.





I am thinking I should plug in an 5AR4 and see what happens.  Would a missing channel be caused from using the wrong rectifier tube?

I am a total newbie when it comes to electronics and am not sure about how to do any other testing.

I will go through the PCB and compare all the resistor values and cap values to make sure my friend installed the right pieces.

Any other suggestions would be great!

Thanks!  - Troy

[poty]

...I thought this was a Cornet as the pcb layout looks exactly as the image provided in the Cornet manual.

Yes, the PCB is Cornet.

However, the pcb clearly reflects a "5Y3" for the rectifier tube.  The 5Y3 is used on the Cornet2.  The 5AR4 is used on the Cornet.

If you look at the photos in the original Cornet manual, you can see that the rectifier marking on the Cornet PCB is also 5Y3. This I think was left from the early Cornet PCB that used 5Y3, different transformer, not used CCS in the last stage... So:

Big question - did I overthink and wrongly use the 5Y3 tube and instead should have used the 5AR4 tube because that is what the rest of the layout supports?  The pcb has "C-02 06 04" in the lower, left corner, which I took to mean cornet version 2, June 2004.
...Would a missing channel be caused from using the wrong rectifier tube?

... in my opinion means only the second version of the first Cornet! In both versions of Cornets you can use 5Y3 or 5AR4 - the choice can't be the source of the problem.

My Cornet as is produces glorious sound, no hum - but only from the left side

This behaviour needs more testing to reveal the problem.

I swapped out all of the tubes one at a time with no difference.  I swapped the interconnects and the channel being out would switch from right to left.  So I believe I eliminated the interconnects or tubes as the culprits.  I also reconnected my Wright phono stage and have been playing LPs so its not the rest of my system.

I hope so.

I will go through the PCB and compare all the resistor values and cap values to make sure my friend installed the right pieces.

It's OK, but more information can be obtained from voltage measuring. Can you do this? If yes (take care of yourself, because there are many high voltage points on the PCB!!!) - could you take measurements on the points marked on the PCB. Especially useful - the voltages on C2, C4, R11 (to the ground) for the silent channel.

[hagtech]

It is most likely a bad connection somewhere.  Could be connector, wire, socket, ...  Try working your way backwards.  Make sure all power supply values are essentially the same in both channels.  Check the plate voltages, they should be hovering around +140V.

I also use a trick - connect the outputs to a headphone amplifier.  Then listen for hum and noise as you probe various nodes with a DVM.  The DVM probe will inject hum into the circuit (so don't have volume too loud).  You should be able to trace this all the way back to the input.  If you can't, then you have narrowed in on the problem area.

jh