Fender Pro Junior

[Rebel]

Hi all.Sorry for my English if it is not perfect.
I have a problem with my Fender Pro Junior. The power Transformer is broken and i can't find an new one. Could you tell me what is the voltage on the secondary winding?so i can order a generic one with this specifc.
I have found this schematic on internet

http://www.webphix.com/schematic%20h...mps/pro_jr.pdf

But i'm not sure it is correct because on the schematic i see on the secondary winding 132 Vac but i think is too low to have more than 300 Vdc on [TP24]. in fact the specific value is 132*1.41=186 and it is different from 319 Vdc.
Can someone help me?
Thanks for your attention,I hope in your reply.

[Jazz P Bass]

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Link: Guitar Nucleus Guitar Parts - Fender Amp Parts
GN49967PT-FEN Power Transformer Fender Replacement 330-0-330 V 120 ma
Fender Original Blues Junior Power Transformer. 15 watts. Equivalent to #049967.

Primary: 117 volt, 60 Hz
Secondary: 330VDC, 68 mA after rectification
Filament winding 1: 6.6 VAC, 2.6 A
Mounting Centers: 2" x 2" horizontal
Weight: 2.6 lbs


$77.95

[Rebel]

Thank you very much for the answer.
So the blues junior and the pro junior have the same power?
can i buy the blues junior transformer for the pro junior without problems?

[Jazz P Bass]

http://music-electronics-forum.com/t19462/
It should be o/k.
If there is a 15 volt winding , tape it off.
EDIT: the 15 volt winding is BRN/ BRN CP16 & CP17 on the schematic.
I have attached the Blues Jr schematic so you can compare the two amps.

[Jazz P Bass]

Better price: Fender Power Transformer, Blues Junior

[Rebel]

thank you very much for the answer and for links.
The only problem is that i live in Italy so i have to buy a transformer with primary windin at 230 Volt.
So i have to find a site with this kind of transformer
do you know some one?

[Jazz P Bass]

The Fender part# is 049968.
(look on the Blues Jr schematic)
I do not about aftermarket availability.

[ThermionicScott]

The Pro Jr uses a different PT (export p/n 041783) with a slightly lower secondary voltage than the Blues Jr. If you're trying to find a generic replacement, note that it uses a bridge rectifier, so you'll be looking at a ~225VAC secondary.

[Rebel]

If you're trying to find a generic replacement, note that it uses a bridge rectifier, so you'll be looking at a ~225VAC secondary.

I have done a simulation with Spice but if i use 225 Vac at the secondary winding i have not 320 Vdc where i need it after rectification.
I have to use a secondary winding at 330Vac in the simulation to have 320 Vdc.
Is it normal?

[Jazz P Bass]

That statement does not compute.
330Vac should not drop when rectified to Vdc.
Vac x 1.4= Vdc.
The final Vdc will depend on the rectifier topology & filter caps.

[Rebel]

This is the result of the simulation.
Could you take a look?

ProJr_Transformer.pdf

I used a transformer with 330Vdc on the secondary winding and i have correct value.
the simulation is wrong?
I did it at the university

[Jazz P Bass]

Simulations are nice & all.
As I have never done one, may I suggest you breadboard the circuit.
Then take your voltage readings.

[ThermionicScott]

I used a transformer with 330Vdc on the secondary winding and i have correct value.
the simulation is wrong?

Yes. A power transformer will have VAC (in RMS) on the secondary. Simulations are great, but they're not reality.

- Scott

[Rebel]

thanks to all for your answers.
I tested the power transformer yesterday and it seems working properly.
instead of 320Vdc on the secondary winding i have 350Vdc on circuit but it is only a little differece that components could be support.
Next time i will not follow the simulation program but only the old rule Vac*1.41=Vdc
thaks to all again!!!