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Hoffman Amps Forum image Author Topic: Must find replacement power transformer!  (Read 3670 times)

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Offline BobbySkidz

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Must find replacement power transformer!
« on: July 05, 2013, 07:29:15 am »
I am trying to find a replacement power transformer for Kustom "The Defender" 50w 1x12 amp.

I can get one from the manufacturer for $80 but would prefer to find a more readily available replacement if at all possible.

Made by a chinese manufacturer named NRE, the transformer is 120v, has 4 primary leads and 7 secondary leads.

A picture of the power transformer label can be found here

Any suggestions would be appreciated. :BangHead:

Offline SILVERGUN

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Re: Must find replacement power transformer!
« Reply #1 on: July 05, 2013, 08:18:33 am »
It might be pretty hard to find an exact replacement that fits in that hole....
If it were any of us, we'd probably enlarge the hole and go with a more common PT
Only problem with that would be finding one that's got the 12-0-12 winding.......looks like that 24vac (converted to -28vdc) is your op amp supply and also provides a DC filament supply for your preamp tubes...
http://www.el34world.com/charts/Schematics/files/Misc/kustom_defender112.pdf

So it might be in your best interest to go with the original replacement you mentioned..............

This is gonna get asked, so I might as well ask it:
How do you know the PT is bad?
« Last Edit: July 05, 2013, 08:34:21 am by SILVERGUN »

Offline eleventeen

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Re: Must find replacement power transformer!
« Reply #2 on: July 05, 2013, 09:54:43 am »
One of those amps was for sale around here, (100 watt model) in perfect shape for $330, with new replacement Celestion speakers worth about $100 ea and it was all I could do not to total up the parts costs and buy the thing on that basis.

IMHO, trying for a non-OEM replacement transformer, you are going to save an absolute maximum of $25 and spend hours searching for it and hours either enlarging the hole or changing something or other....and in the end, you will pay for the savings you envision by working for $3 an hour.

That is my one-sentence comment on your situation.

stratele52

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Re: Must find replacement power transformer!
« Reply #3 on: July 05, 2013, 02:15:59 pm »
Better to buy original , no trouble .

You are sure PT do not work ?

Offline jarmoke

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Re: Must find replacement power transformer!
« Reply #4 on: April 17, 2015, 01:59:22 am »
Does anyone know, where to find original transformer?
I have for sure broken one in my friends amp. One of the
120v coils is blown...

Offline octal

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Re: Must find replacement power transformer!
« Reply #5 on: April 17, 2015, 07:34:24 am »
Looks like that transformer has thermal fuses in it. If one or both the primaries are open, you might be able to peel back the wrap around the winding and just replace the thermal fuse(s), taking care to insulate everything carefully after reassembly.

Offline mresistor

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Re: Must find replacement power transformer!
« Reply #6 on: April 17, 2015, 10:59:54 am »
I read also that if you could reach the fuse and it's bad, you could jumper around it (bypass) and the PT might work many more years.


« Last Edit: April 17, 2015, 04:09:20 pm by mresistor »

Offline eleventeen

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Re: Must find replacement power transformer!
« Reply #7 on: April 17, 2015, 01:35:11 pm »
Maybe I'm going out on a limb here, but IMO placing fuses under the wrapping of a power transformer is goofy.

Offline mresistor

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Re: Must find replacement power transformer!
« Reply #8 on: April 17, 2015, 04:41:24 pm »
Here's an interesting thread about internal PT fusing

makes me wonder when mfg's started doing this and how many of mine are internally thermally fused. ?

 


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