New Ceriatone Overtone build with a few q. Completed!

[chikov]

Hello friends,
My name is Alex and I am new here. Structo played a big part in turning this Russian guy from Texas, into a guitar tech who is trying to become an amp tech too . I repaired and moded many amps, but never built one. I've studied several videos and books by Gerald Weber, but it is time for me to really learn how to build and voice the amp... I followed Tom's advice and got a kit from Ceriatone. I have to praise them for their quality.
I do have a question though... On their layout they have a Ground switch but it is not wired??? How do you wire it?

[IMG:640:423]http://i409.photobucket.com/albums/pp171/alexjohnne/100WOvertone051109-2_zpsb5f43230.gif[/img]

[IMG:640:461]http://i409.photobucket.com/albums/pp171/alexjohnne/Overtone100-V2-Ceriatone_zps3c808aee.jpg[/img]

In the beginning:

[IMG:640:480]http://i409.photobucket.com/albums/pp171/alexjohnne/DSCN1423_zps351fec53.jpg[/img]

[chikov]

They have it wired on the photo, but not on the layout... weird...

[IMG:600:450]http://i409.photobucket.com/albums/pp171/alexjohnne/groundswitch_zps4cdda7aa.jpg[/img]

[amplifiednation]

I would omit the ground switch from the amp. Throw a grommet in the hole, or wire it as half power or something.

IIRC the ground switch changes polarity of the incoming power line, and that's not a good thing these days

[halfbackstrat]

I have mine wired as a pentode triode switch

I believe the ground switch voids the amp from passing any official electrical safety regulations? I could be wrong about that.

[chikov]

I would omit the ground switch from the amp. Throw a grommet in the hole, or wire it as half power or something.

IIRC the ground switch changes polarity of the incoming power line, and that's not a good thing these days

Great idea! I am planning on modifying this amp in the future anyway, so I will keep that switch handy... But no ground switch in the mean time.

[Teleguy61]

Very handy for a half power switch.

[chikov]

I am not sure how to wire the half power switch... Could you give some details please?

BTW, some one sent me PM asking to send them the schematic for this amp in full resolution, but my reply went into "debug mode" - don't know what it is. However, you could double click on the picture of the schematic and it should take you to photobucket.com where you could enjoy the full resolution.

[Teleguy61]

I am not sure how to wire the half power switch... Could you give some details please?

BTW, some one sent me PM asking to send them the schematic for this amp in full resolution, but my reply went into "debug mode" - don't know what it is. However, you could double click on the picture of the schematic and it should take you to photobucket.com where you could enjoy the full resolution.

I wasn't able to find a thread in a quick search, although I'm sure they are here.
Basically, one pair of output tube grounds, either the inside pair, or outside pair, not a pair on one side only, have their grounds, which run through the 1 ohm bias resistors, on a switch that disconnects them from ground.
No ground=no current flow=no output.

[martin manning]

#124 schematic has a half-power switch.

[chikov]

Thanks guys for the help. I followed your advice and wired the toggle switch as 50W/100W option. #124 has a light indicator but I can wait on that. Here is the pic of my switch wiring. It looks like the ground wire is going to the hot side of the power plug but it is just an illusion - it goes to the ground...

[IMG:640:480]http://i409.photobucket.com/albums/pp171/alexjohnne/DSCN1426_zps55972f3f.jpg[/img]

[Teleguy61]

#124 schematic has a half-power switch.

Thank you Martin.

[chikov]

Hi guys, it looks like I ran into a minor problem. I just got my transformers from Classic Tone. Well, the power one seems to lack some wires. The schematic asks for 3.15-0-3.15V for filaments and it has 6.0 - 0 only. I also need 6.0 for another part of the schematic??? And, the layout says I need 340V , but this transformer gives me only 320-0-320V - will it work?
Plus, the transformer is too big and does not fit in chassis... Can I make it work or should I send it back?

[IMG768]http://i409.photobucket.com/albums/pp171/alexjohnne/Mobile%20Uploads/c35ae556-3434-4d8f-ad7e-fb2ca494cbfe_zpsa29ebbad.jpg[/img]

[chikov]

I looked at Twin Reverb schematic and found that they use the 2 green wires for the filaments (0V-6V instead of 3.15-ground-3.15) - I can do that too, but can I use the same power source for my relays power supply?

[martin manning]

Note 320-0-320 is loaded to 450 mA. You should be fine.

No CT on the 6.3VAC heater winding means you just add two 100 ohm resistors to create a faux CT (the "0"). No problem there.

Doesn't fit the cut out? Do you have nuts between the chassis and the transformer? You should, and that will raise it up a bit and get more clearance. If it still doesn't fit, enlarging the cut-out would be a pain.

Ceriatone PT's have an extra 6V winding for the relay supply, but you can easily add a small transformer from Radio Shack like Dumble did.

[chikov]

Thank you, Martin, for saving my day! Yes, I have the whole box of power supplies and some of them are 6V for sure. Now, I am still a little new for some of this stuff, so could you explain (if you have time), what does CT stand for and how exactly I wire 2x100oHm resistors? I am sorry - I googled it , but found nothing... Thanks.