Im having trouble finding the right power transformer for my Squier
15G guitar amp.  I have found 6 different kinds at the radio shack
website, but im not sure which one is the right one.  I bought my amp
when i was in Germany, it has 220v power supply.  I removed that
transformer and wish to replace it with one that will work with the US
standard 115v.   Can anyone give me a lead on which transformer i
should get.  I need to know the proper output the transformer put out
or what the circuit board can handle.

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Clarification of Question by realimages-ga on 11 Dec 2002 10:30 PST

I have called a couple of dealers that sell Fender parts and they said
Fender doesnt make the power transformer anymore.  Im sure one of the
transformers at radio shack works but not sure which one.

Hello realimages,

Great question!

I was able to track down the schematics for your amplifier. You can
view them at the following link. You will need Adobe Acrobat to read
it :

15G Schematics
http://www.mrgearhead.net/faq/schematics/fender/Frontman%2015G%20Schematic%2068F.pdf

After viewing the schematics I was able to find a company that stocks
genuine Fender parts and replacements, including your transformer :

Parts Smart
Phone: 847-342-8266
http://www.partssmart.com
15G Parts list
https://aetna.ntsecure.net/partssmart/old/Front15-15R.html


The part number for the original 120V transformer is 0025413-000.
According to the schematics, the output is 16.4 Volts. (center tapped
with a 1Khz input signal) This would give it a full nominal AC
stepdown voltage of @33 volts.

I wasn't able to cross reference any part numbers for this transformer
to find an alternative replacement. I can tell you that the ones at
Radio Shack are rated up to 2 Watts or so, but none seem to meet the
secondary winding requirements. I would contact the company above to
see what alternatives they have. Their site says they can get you any
part, or the equivalent. When you speak with them, simply say you need
the main transformer, and give them the page with 15G data that I gave
you for reference.

There is another solution besides getting the transformer and altering
your amp. For a comparitive price (maybe even lower), you could order
a step up transformer that will meet the requirements of your
amplifier. Here are some to look at for only $59.00 :

Step up (110v/120v to 220v) transformers
http://transadapt.com/voltage-su.html

More step up (110v/120v to 220v) transformers
http://www.travel-arts.com/page6.htm

This way you would still be able to use the amp should you travel
again. All you would have to do is put the transformer back in, and
plug into the step up transformer. :-)


To help find this answer I searched Google for:

transformer guitar amp
://www.google.com/search?q=transformer+guitar+amp

fender 15g schematics
://www.google.com/search?q=fender+15g+schematics


I would love to hear how this works out for you! Good luck with your
amp and happy playing!

SgtCory

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Clarification of Answer by sgtcory-ga on 11 Dec 2002 16:18 PST

I forget to mention - should you need clarification, feel free to ask
at any time, as I would love to help further.

Thanks again,
SgtCory

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Clarification of Answer by sgtcory-ga on 12 Dec 2002 13:18 PST

I see you found a new site. None of the ones you listed suffice, but
these ones may -

32V center tap (look down the page and contact them)
http://www.mgs4u.com/transform.htm

32V center tap (any would work - but go with the least you need -
call)
http://www.jmtransformer.atfreeweb.com/splitbobbinpower.html


One of those should suffice :-) I hope this helps a little more.

Thanks again,
SgtCory

Thank you very much for the work

realimages...

The circuit board will only draw the current that it
needs. The critical issue is what is the voltage 
output of the transformer. The 220V transformer may
have some writing on it, indicating the voltage out.
The power transformer is called a step-down transformer,
and reduces the 220V or 110V to the ideal input voltage
for your power supply. The output will still be AC volts.
Your power supply then takes this stepped-down AC voltage
(maybe 24V, 12V, 6V) and converts it to DC voltage for 
use by the circuit boards in the amplifier. Some
transformers have a 'center tap' as well, dividing the
output (say 12V) into two 6V outputs, or a 3V and a 9V
output, eached used in different parts of the circuitry.

What you need to find out is the output voltage(s) of the 
220V transformer you have. Perhaps you have a friend who
has a voltmeter to measure this. The you would want to
know the amperage rating of the transformer - meaning that
it will deliver the 12VAC at what amperage (how much current)
without burning out. If you are unable to determine this
from markings on the transformer you have, you could simply
buy a 110V transformer that is rated higher than what you
would reasonably need. The fact that a transformer CAN
handle more current, doesn't mean that it will force more
current into your amp than is normally drawn by the circuitry.
See? Let me know if this helps, and what else you need.

so what you are saying is that if the transformer is slightly over the
required output to the circuit board it wouldnt hurt the board?

sublime -

Great comments.

realimages -

You could go over the current rating, as a circuit will only draw as
much current that is needed to operate the circuit. You would not want
to go over the secondary voltage rating :-) (around 33-35 volts AC).
All of the transformers that you listed at the Radio Shack site are
under voltage. This could cause stress on the transformer, as the
circuit will try to draw current that is not available. (according to
the secondary information given at the RS site)

The secondary voltage is fed into the rectifier circuitry to convert
it to DC. Going over the stated voltage will surely cause damage to
this circuit area.

Did you contact the company I listed? Let me know how it goes -

SgtCory

i contacted that site and they got with fender to get the part but
fender doesnt make it anymore, the guy told me i could possibly get it
rewound but that wouldnt be worth the money to go that route, any
ideas where i could find another site?

realimages...

This is where you might have to get creative.
If it were my amp, I'd look for a transformer that
provided outputs of 16.4vac and 32.8vac, which is
what I did. Such a transformer is listed on the 
following webpage, on the Surplus Sales of Nebraska
site, as TP2108. It also has secondary outputs of
65.6vac, 82vac, and 98.4vac, which you would not 
use. If you bought this transformer, the outputs
might not be labelled, and you might need to use
a voltmeter to measure the output voltages, so you
could find and use only the correct ones. In order
to duplicate the dual 16.4vac inputs required by
your amp, you would need to use the 16.4vac output
with ground, and the 32.8vac output with the 16.4vac
output. Also note, that, per the schematic given
by sgtcory, you would need to replace the current
250ma fuse (F1) with a 500ma fuse.
http://www.surplussales.com/transformers/transflisted.html

You could also go the route of using a slightly lower
voltage output, such as the 14vac/28vac output of this
transformer (TP)9071Z:
http://www.surplussales.com/PowerTra.html

This transformer is rated at 4 amps, and should be
able to handle the extra load imposed by your 
circuitry, which is fused at 500ma, or 1/2 amp.

And, yes, rewinding a transformer would not
be cost effective.

Hope that helps.

I found a site called Jameco.
here is what i found, will one of these work?

*TRANS,PWR,12.6VCT/2A
Voltage Input (center tap): 115/230VAC 
Color Code Input: Black -Yellow-Red 
Voltage Output: 12.6VCT @2A 

*TRANS,PWR,12.6VCT/4A, 
Voltage Input: 115VAC 
Color Code Input: Black - Black 
Voltage Output: 12.6VCT @4A 

*TRANS,PWR,12.6VCT@4A
Voltage Input (center tap): 115/230VAC 
Color Code Input: Black-Red-Yellow 
Voltage Output: 12.6VCT @4A 

*TRANS,PWR,18Vct/2A
Voltage Input (center tap): 115/230VAC 
Color Code Input: Black-Red-Yellow 
Voltage Output: 18VCT @2A

*TRANS,PWR,18VCT/1A
Voltage Input (center tap): 115/230VAC 
Color Code Input: Blue-Red-Black 
Voltage Output: 18VCT @1A

Im willing to bump up the price if someone can help me find the
transformer i need.  Thankyou