Help for an old project

[Tele65]

Dear all hope you're doing fine! I'm not visiting the forum from a very long time... lot of things in between from the last time... a couple of bands, a new kid, and Helix and a Kemper... but the tube amps mojo still is there... and I'm presently waiting for a new Ox Box... so my old project of a 18W head deserves new attention... I want to complete it but I've lost all the documentation about parts used and also the schematic I was following duruing the build... is there any angel out there able to tell me precisely which version of the amp is this and also where I can find a wiring scheme? Sounds funny I know but... thanks in advance!!!

Fabio

[Bieworm]

Looks like a straight up 18W TMB to me...
With the misleading gain knob called MV, which it isn't..

[geoff 1965]

Hello Fabio,
very nice kit! it looks like the layout is ceriatone,do the component values on the board match this layout?

18wattTMBceriatone (2).jpg

[Tele65]

Hello Fabio,
very nice kit! it looks like the layout is ceriatone,do the component values on the board match this layout?
18wattTMBceriatone (2).jpg

Hi Geoff! Sure Nik is involved here! Both my previous builds are based on Ceriatone kits, and probably this is no exception...! Thanks a lot indeed!

Cheers
Fabio

[Bieworm]

Hello Fabio,
very nice kit! it looks like the layout is ceriatone,do the component values on the board match this layout?
18wattTMBceriatone (2).jpg

Hi Geoff! Sure Nik is involved here! Both my previous builds are based on Ceriatone kits, and probably this is no exception...! Thanks a lot indeed!

Cheers
Fabio

Didn't come cheap either. Those caps and transformers aren't the cheapest

[geoff 1965]

yeah potential there for a top quality amp,one of the best overdrive/tone i’ve heard on the forum was Luri’s ceriatone.
good luck with the build and keep us posted with your progress Fabio.

[Tele65]

Hello Fabio,
very nice kit! it looks like the layout is ceriatone,do the component values on the board match this layout?
18wattTMBceriatone (2).jpg

Hi Geoff! Sure Nik is involved here! Both my previous builds are based on Ceriatone kits, and probably this is no exception...! Thanks a lot indeed!

Cheers
Fabio

Didn't come cheap either. Those caps and transformers aren't the cheapest

You bet my friend! I tried to purchase the best components I can afford... and that's the reason why I choose MM Radiospares irons... and the build is taking so much time! You all guys gave me really a good hand! Thanks a lot indeed... Searching in the mails I found the thread with Nik and some old issues I forgot just on trannies... I will share it here hoping they are of some interest and if any of you have some experience in using these trannies, please share it!

Quote
18 watt clone
Posta in arrivo

Fabio Pollero <fpollero@gmail.com>
gio 16 giu 2016, 17:15
a Nik

Dear Nik,

I'm building from scratch a 18W TMB following your schematic and got some problem with the
PT which I've purchased.

The PT is a Mercury Magnetics P18RS. The transformer has the following layout (eylets instead of wires so there is no color to be followed)

Primaries (left side):
240
220
120
100
0
0
CT
6.3

Secondaries (right side):
6.3
5
0
316
0
316
SCN Shield (ground)

According to the schematic I should use 2x290 VAC on pins 1 and 7 of the EZ81 but I have 316 VAC instead. Is the voltage compatible with the rectifier? Also the filaments are confusing
since the schematic shows a 6.3 from the primaries on pin 5 and a zero on pin 4 but I do have two 0 on the primaries... which is the right 0 to be used?

Have you a tip to share for the wiring of this transformer? I'ts pretty different from what I'd expect...

Thank you very much in advance my friend and forgive the trouble I'm giving you!!!

Cheers
Fabio
Unquote

I also applied to the guys at MM and this is their reply:

quote
Hi Fabio,



Thank you for choosing Mercury.

On the left side you will be using OV (under the 100V tab) as your common and 240V for your input voltage assuming you are at 240V wall voltage.

The OV and 6.3 on that side are your filaments and CT meaning the center tap of the filaments.

On the right side 316 0 316 is your B+. 0 being the center tap of the B+

The 0 and 5V is your 5 volt for the tube rectifier. If using an EZ81, you can use the OV and 6.3 instead of the 5V.

If still in doubt, you will need a qualified tech to install or check your work before powering the amp on.

The P18RS is a clone of an original Radiospares PT from an original amp that we prefer.

The original schematics are all plus minus 20% all voltages and there was no consistency.

The higher B+ will sound clearer and more articulate.
Patrick
unquote

Thanks you all guys!

Fabio

[Bieworm]

Don't worry about the 316V HT. Get a bunch of zener diodes 5V 5W to get the B+ on spec after tge HT's are recitied. There's help and info here about that

[geoff 1965]

the 316-0-316 will probably be open circuit “unloaded” voltages,with the valves in it should drop close to 290-0-290.
wow! just seen how much they cost!

[crgfrench]

Nice build so far!

[colossal]

the 316-0-316 will probably be open circuit “unloaded” voltages, with the valves in it should drop close to 290-0-290.

This is correct. Mercury lists unloaded voltages.

[JMPGuitars]

the 316-0-316 will probably be open circuit “unloaded” voltages, with the valves in it should drop close to 290-0-290.

This is correct. Mercury lists unloaded voltages.

Yup. I wonder what the actual loaded voltage is. They also have a "low B+" version, but their new site doesn't specify the voltage.

[crgfrench]

They also have a "low B+" version, but their new site doesn't specify the voltage.

The P18RS-M is 302-0-302.

[JMPGuitars]

They also have a "low B+" version, but their new site doesn't specify the voltage.

The P18RS-M is 302-0-302.

That's not the loaded voltage though.

[crgfrench]

They also have a "low B+" version, but their new site doesn't specify the voltage.

The P18RS-M is 302-0-302.

That's not the loaded voltage though.

Correct -- same unloaded quote as 316-0-316 for the P18RS.
Probably the loaded voltage for the P18RS-M will be about 14V lower than whatever the loaded voltage you see from the P18RS.