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Topic: Nashville 400 - Convert to 240 Volt |
John Egenes
From:
Port Chalmers, New Zealand
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Posted 5 Dec 2022 1:27 pm |
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I still haven't gotten around to converting my old Nashville 400 from 120 to 240 volt. I'm in New Zealand, so parts are hard to come by, and shipping costs from America are usually prohibitive. That said, does anyone have any suggestions for replacing the transformer and converting the amp to 240 volts?
I have read about some solid state ideas, and other ways to use a lighter-weight transformer, but I'm not an electrical geek so I am unsure about any of that. But I'm open to ideas, and would likely find someone here to do the work. Thanks.
--john |
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Dave Grafe
From:
Hudson River Valley NY
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Posted 5 Dec 2022 3:31 pm
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| Before chopping into it make sure the existing transformer does not already have a tap on the primary for 240v |
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John Egenes
From:
Port Chalmers, New Zealand
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Posted 5 Dec 2022 3:38 pm
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Dave:
Good point. It's been a while, but I'm pretty sure it doesn't. Will check, though. Thanks.
--je |
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Chris Clem
From:
California, USA
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Posted 5 Dec 2022 4:23 pm
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Why not use a step-down transformer. It is a separate transformer that will change the 240 to 120 and you wouldn't need to change anything in the amp.
Here is a link from Australia. Just as an example of what they are.
https://wallcann.com.au/100w-step-down-transformer/
Last edited by Chris Clem on 5 Dec 2022 4:34 pm; edited 1 time in total |
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Dave Grafe
From:
Hudson River Valley NY
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Posted 5 Dec 2022 4:24 pm
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This schematic shows two different transformers available, unfortunately the Triad part number for the 240v unit is obscured. You can check the part number on yours to see, but it doesn't look like they used a multi-tapped primary at all. |
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John Egenes
From:
Port Chalmers, New Zealand
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Posted 5 Dec 2022 6:06 pm
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Chris:
I do use a stepdown transformer. I've had it here in NZ for 18 years, and it's a pain to lug it around. Also, it doesn't exactly produce a "clean" amp signal [grin]. And yep, I've tried several SD transformers over the years, and none is as good as just having normal 240 volt, 50 cycle power.
Dave: Thanks for the schematic. I'll save it and ask some electronic geeks about replacement parts.
best, --je |
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Paddy Long
From:
Christchurch, New Zealand
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Posted 5 Dec 2022 7:02 pm
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John my old Nashville 400 has a standard 240v transformer in it ...probably built originally by Peavey for the Aussie and NZ market... I bought it new with the 240v tranny ... I imagine you can do a straight swap, just need to beef up the fuses etc ... but you would need a amp tech to confirm any of that. Using a step up transformer is not a great idea, I had one of those with my Session 400 way back, and it was a pain having to carry that heavy transformer around as well as the amp.
_________________
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Telonics, Peterson, Steelers Choice, Benado, Lexicon, Red Dirt Cases. |
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Donny Hinson
From:
Glen Burnie, Md. U.S.A.
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Posted 5 Dec 2022 7:48 pm
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Original 240v "Export" transformer was part number 705-16740, made by either Triad or Basler. Very rare bird!
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John Egenes
From:
Port Chalmers, New Zealand
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Posted 5 Dec 2022 9:02 pm
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Hi Paddy. Good to hear from you. And yep, the stepdown transformer is a pain to lug around. It's the main reason why I haven't been using the Nashville 400 for a while. Am using a 2X12" Deluxe type amp right now and it's fine, but I wouldn't mind putting the old 400 back to work. Will suss out a supplier for a 240 volt transformer. It's not hard to find one with the right specs. Much more difficult to find one that will fit into the amp easily. Fortunately, I'm not in a hurry [grin].
best,
--john |
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John Egenes
From:
Port Chalmers, New Zealand
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Posted 24 Dec 2022 5:12 pm
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Donny Hinson,
Thanks for that info. I'll try to track one down. I won't hold my breath, but you never know! |
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ajm
From:
Los Angeles
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Posted 25 Dec 2022 11:56 am
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If you run out of avenues to try, try Googling "guitar amp transformers".
You could start with Mercury Magnetics and branch out from there.
You could also try Peavey if you haven't done it yet. (That would probably have been my first step.) |
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John Egenes
From:
Port Chalmers, New Zealand
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Posted 25 Dec 2022 12:08 pm
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ajm:
Thanks for the tip. I'll check with Mercury Magnetics, for sure. I know the Model number of the transformer, but I don't really know any of the specs. And since I'm pretty much a hack when it comes to electronics, I'm not really sure exactly what I'm shopping for. Would really like to get something that just bolts right in and works, but that might be asking too much. [grin] |
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Scott Swartz
From:
St. Louis, MO
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Posted 25 Dec 2022 2:51 pm
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John, a reasonable guess would be the higher voltage supply for the power amp would be 40-0-40 volts. A properly designed power supply with a center tap transformer will usually run at about 1.3 times the "half voltage (40)" so 40 x 1.3 = 52.
You could use a small second transformer for the preamp +/- 15 volts supply, since that is shunt regulated with those zeners and therefore need higher voltage before the zeners, I would guess that winding is 15-0-15.
Hammond makes filament transformers that could be used for each of the above, but this is a big job that requires a lot of expertise and modification.
Also you could get exact numbers by using your step up transformer and taking measurements inside the amp.
Searching for one of those export transformers would be your best bet.
_________________
Scott Swartz
Steeltronics - Steel Guitar Pickups
www.steeltronics.com |
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John Egenes
From:
Port Chalmers, New Zealand
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Posted 25 Dec 2022 4:22 pm
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Scott:
Thanks for the info. Mostly alien language to me, but it definitely helps, and I'll copy it for later reference. Right now I am using a stepdown transformer (240 to 120 volts), but I have no idea what the values would be if I measured them. The problems with the stepdown include: too heavy to carry around; 50 cycle for a 60 cycle amp; creates hum if it's too close to the amp (and onstage, that's often the case...). I have 3 or 4 SDT's, but I have to use the big one because the Peavey draws a lot of power. --je |
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Steve Sycamore
From:
Sweden
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Posted 15 Jan 2023 3:00 pm
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The main thing you need to do is to change the power transformer. The fuse(s) need to be changed also. If you are serious I will look over the schematic diagram again and come with more details.
I've been meaning to do this for my Nashville 400 (decades ago) but have so many other things going on I haven't gotten around to it and haven't been taking the amp out anywhere anyways.
The transformer to do it is right in front of me now. I chose an Antek toroidal transformer with additional taps for the +-15v supply needed for the amp.
https://www.antekinc.com/as-4438-400va-38v-transformer/
The similar +-40v model might work well too, but I've used these transformers before and they seem to run a bit on the high side in voltage, at least with 230V mains.
P.S. If you haven't worked with power supplies before I would order the transformer and take it and the amp to a local technician. It's a straightforward job but mistakes made can be lethal. That transformer can easily deliver 500 watts in a split second. |
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Jeff Highland
From:
New South Wales, Australia
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Posted 15 Jan 2023 4:24 pm
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| Steve Sycamore wrote: |
The main thing you need to do is to change the power transformer. The fuse(s) need to be changed also. If you are serious I will look over the schematic diagram again and come with more details.
I've been meaning to do this for my Nashville 400 (decades ago) but have so many other things going on I haven't gotten around to it and haven't been taking the amp out anywhere anyways.
The transformer to do it is right in front of me now. I chose an Antek toroidal transformer with additional taps for the +-15v supply needed for the amp.
https://www.antekinc.com/as-4438-400va-38v-transformer/
The similar +-40v model might work well too, but I've used these transformers before and they seem to run a bit on the high side in voltage, at least with 230V mains.
P.S. If you haven't worked with power supplies before I would order the transformer and take it and the amp to a local technician. It's a straightforward job but mistakes made can be lethal. That transformer can easily deliver 500 watts in a split second. |
Won't you need a centre tapped +40 0 -40 transformer or +38 0 -38 not just 0 38 as that seems to be? or are the specifications deficient and there are actually two 38v outputs which would allow for the correct wiring.
_________________
Duesenberg Fairytale
1949 Supro Supreme
1950 National New Yorker
2008 Highland Baritone Weissenborn
2020 Highland New Yorker.
2020 Highland Mohan Veena
2021 Highland Weissencone
Last edited by Jeff Highland on 15 Jan 2023 5:03 pm; edited 1 time in total |
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John Egenes
From:
Port Chalmers, New Zealand
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Posted 15 Jan 2023 5:01 pm
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Steve Sycamore:
Thanks very much for this info, especially for posting a specific transformer for the job. I'll see if I can locate this transformer here in New Zealand (shipping costs from the USA are ridiculous these days...). I really appreciate it. And yes, I do have a qualified tech who can do the work. I'm not gonna fry myself with 240 volts just for the sake of an amp upgrade [grin]. --je |
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Steve Sycamore
From:
Sweden
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Posted 16 Jan 2023 9:01 am
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| Jeff Highland wrote: |
Won't you need a centre tapped +40 0 -40 transformer or +38 0 -38 not just 0 38 as that seems to be? or are the specifications deficient and there are actually two 38v outputs which would allow for the correct wiring. |
Yes, the specifications seem deficient at their website for some reason. When I ordered that unit some years ago the site looked fine. It has 38-0-38 plus 15-0-15 secondary taps. Actually they are doubled in both cases: 38-0 38-0 and 15-0 15-0. I can read those (not with particular ease) on the transformer itself. I'm pretty sure I printed the proper specifications and have the paper tucked away somewhere.
Otherwise, the specs such as voltage drop with load and such are pretty similar to the 40v model (where the specs are intact). Those transformers are power monsters! |
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