Toroidal Transformer for JCM800 -- PREAMP

[andregarcia57]

Hello to all the beauty,
I'm riding in the JCM800 Preamp for use as pedal and like to exchange ideas ...

I have ridden this preamp transformers with normal ...

Now I recently bought AMVECO 70001K for use internally on my pedal ... he came without a diagram and has 4 pins on the 9V and four pins on the 115v.

the connection is correct as the image below?

I appreciate your help
André

[FYL]

Now I recently bought AMVECO 70001K for use internally on my pedal ... he came without a diagram and has 4 pins on the 9V and four pins on the 115v.

I don't think this will work: the PT is only rated for 18 VAC @ 89mA. You need 150 mA per 12AX7 just for heaters, plus iron, recto and regulator losses, plus something like 3 mA for B+ per 12AX7 plus... Use a > 500 mA PT for a two tube std preamp.

Heater supply will also be a problem voltage-wise: 18V Ac gives around 24V DC after the diodes. The 7812 can accept 35V but is only rated at up to 19V for std operation. You don't want to waste too much power in the regulator, with 24V you'll need to dissipate something like 5 watts, way too high for a pedal where space is at a premium. Using a 12V PT will give around 16V DC, with slightly more than 1W dissipation in the 7812.

[andregarcia57]

Now I recently bought AMVECO 70001K for use internally on my pedal ... he came without a diagram and has 4 pins on the 9V and four pins on the 115v.

I don't think this will work: the PT is only rated for 18 VAC @ 89mA. You need 150 mA per 12AX7 just for heaters, plus iron, recto and regulator losses, plus something like 3 mA for B+ per 12AX7 plus... Use a > 500 mA PT for a two tube std preamp.

Heater supply will also be a problem voltage-wise: 18V Ac gives around 24V DC after the diodes. The 7812 can accept 35V but is only rated at up to 19V for std operation. You don't want to waste too much power in the regulator, with 24V you'll need to dissipate something like 5 watts, way too high for a pedal where space is at a premium. Using a 12V PT will give around 16V DC, with slightly more than 1W dissipation in the 7812.

ok, so I use it, please take a look at the site.

70042 or other?
http://www.amveco.com/Low_Profile_PC.htm

thanks

[FYL]

You should use a larger first PT, with at least 500 mA @ 12V. Doug lists a number of external wall-warts wich
 are purrfect for preamp duties.

http://www.hoffmanamps.com/MyStore/perlshop.cgi?ACTION=enter&template&thispage=Transformers&ORDER_ID=!ORDERID!

A small PT such as the one you've listed is then OK for B+, with only a few mAs of current drawn.
Check this schemo for connections:
http://www.el34world.com/projects/images/TubePedalSchematic.gif

Mains => wall wart => 12V AC => Recto => Reg = Heaters
                                         => small PT => 200+V AC => Recto = plates

[andregarcia57]

You should use a larger first PT, with at least 500 mA @ 12V. Doug lists a number of external wall-warts wich
 are purrfect for preamp duties.

http://www.hoffmanamps.com/MyStore/perlshop.cgi?ACTION=enter&template&thispage=Transformers&ORDER_ID=!ORDERID!

A small PT such as the one you've listed is then OK for B+, with only a few mAs of current drawn.
Check this schemo for connections:
http://www.el34world.com/projects/images/TubePedalSchematic.gif

Mains => wall wart => 12V AC => Recto => Reg = Heaters
                                         => small PT => 200+V AC => Recto = plates

ok I'm using external 12V 1A transformer,
I'll use to test this toroidal 70001k,
more like I turn to the 70001k 18v?
correct connection of the transformer?
grateful

[FYL]

If the PT puts out 240 V with 18 V on the primary, it's output with 12 V on the primary will be roughly 240 * (12/18) = 160 V.

[andregarcia57]

If the PT puts out 240 V with 18 V on the primary, it's output with 12 V on the primary will be roughly 240 * (12/18) = 160 V.

yes but I wonder if the pin connection is correct, because it has no wiring diagram.

entering 5 and 8 coming from the 12V output of the transformer, 6 and 7 solder.

1 and 4 out 220v, 2 and 3 solder.

[FYL]

yes but I wonder if the pin connection is correct, because it has no wiring diagram.

From the Amveco web site
http://www.amveco.com/Low_Profile_PC_2.htm#pin_layout