Switchable Power Supply (110/220V) Support

by PatrickJ Sat Feb 22, 2014 1:22 am

PatrickJ: Posts : 1
Join date : 2014-02-22

Post n°1

Switchable Power Supply (110/220V) Support

by PatrickJ Sat Feb 22, 2014 1:22 am

Hi,
I'm looking at your product specs and see that there is an option to purchase a 240V version for the Euro market. Can you check if this is switchable to 110V for dual mode operation - I'm currently in the US but could relocate to Europe in 1-2 years.

Alternatively, what would you estimate the cost to be to replace the 110V ps with a 240V version in the future?

TIA,
Patrick

by erlingt Sat Feb 22, 2014 9:05 am

erlingt

erlingt: Posts : 16
Join date : 2010-06-23
Location : Denmark

Post n°2

Re: Switchable Power Supply (110/220V) Support

by erlingt Sat Feb 22, 2014 9:05 am

I have the 240V version of a VTA ST-70. The only difference is the power transformation - and it is not switchable.
You have to change the power transformer, or use an step down transformer in front of the amplifier to bring the net voltage down.

by **Bob Latino** Sat Feb 22, 2014 10:34 am

Bob Latino

Bob Latino: Admin; Posts : 3263
Join date : 2008-11-26
Location : Massachusetts

Post n°3

Re: Switchable Power Supply (110/220V) Support

by Bob Latino Sat Feb 22, 2014 10:34 am

erlingt wrote:I have the 240V version of a VTA ST-70. The only difference is the power transformation - and it is not switchable.
You have to change the power transformer, or use an step down transformer in front of the amplifier to bring the net voltage down.

Erling,

You do not have to change out the power transformer ..

All the 240 volt VTA ST-70 and ST-120 amps (kit or wired) have dual primaries .. They may be used at 120 VAC or 240 VAC. When you build the amp from a kit you may set the amp up for EITHER voltage. Also - It is a simple task to change the location of two wires and switch voltages at a later date ...

The VTA ST-70 dual primary 120/240 volts transformer is + $35 USD over the price of the 120 volt only power transformer.
The VTA ST-120 dual primary 120/240 volts transformer is + $50 USD over the price of the 120 volt only power transformer.

Below are the wiring instructions for the dual primary ST-70 120/240 volt PA-521 power transformer for both 120 and 240 volt.

For 240 volt operation (Europe/Australia) with the PA-521 transformer connect the BLACK lead to lug A of the fuse post (S). Connect the VIOLET lead to lug # 1 of the on/off switch (S). Connect the VIOLET/WHITE and BLACK/WHITE leads TOGETHER (S) and then insulate this soldered connection with electrical tape or Teflon shrink wrap.

For 120 volt operation (USA and Canada) with the PA-521 transformer twist together the BLACK and BLACK/WHITE leads and connect BOTH to lug A of the fuse post (S). Twist together the VIOLET and VIOLET/WHITE leads and connect BOTH to lug # 1 of the ON/OFF switch. (S)

Bob

by Alan-14 Sat Mar 01, 2014 10:24 am

Alan-14

Alan-14: Posts : 46
Join date : 2012-03-31
Age : 63
Location : Melbourne - Australia

Post n°4

Re: Switchable Power Supply (110/220V) Support

by Alan-14 Sat Mar 01, 2014 10:24 am

Oh why oh why didn't you have the 240V option available when I built my ST-120 a couple of years ago Bob.

Guess you must have had an increasing number of enquires for 240V versions since Smile

by **Bob Latino** Sat Mar 01, 2014 12:52 pm

Bob Latino

Bob Latino: Admin; Posts : 3263
Join date : 2008-11-26
Location : Massachusetts

Post n°5

Re: Switchable Power Supply (110/220V) Support

by Bob Latino Sat Mar 01, 2014 12:52 pm

Alan-14 wrote:Oh why oh why didn't you have the 240V option available when I built my ST-120 a couple of years ago Bob.

Guess you must have had an increasing number of enquires for 240V versions since

Hi Alan,

Yes - I have been getting more and more requests for 240 volt versions of the VTA amps over the past two years. As such, I do now have a 120/240 volt versions of all the VTA amps. These power transformers are special order only and take about a month for me to get after receipt of payment.

The 120/240 power transformers are "dual primary" transformers and may be operated on either voltage with a simple (move two wires) wiring change.

Bob

by Alan-14 Sat Mar 01, 2014 9:21 pm

Alan-14

Alan-14: Posts : 46
Join date : 2012-03-31
Age : 63
Location : Melbourne - Australia

Post n°6

Re: Switchable Power Supply (110/220V) Support

by Alan-14 Sat Mar 01, 2014 9:21 pm

Hi Bob,

I had thought about ordering a 240V transformer from you ... but the amount of work required to replace the transformer is not exciting me at all.
My ST-120 has been working perfectly for the last two years with the stepdown tranformer so I'm hesitant to rip it apart at this point.
Maybe in another couple of years Smile

Actually ... one question ...
Would I be correct in assuming a 240V transformer would run significantly cooler that the 120V version?
Given the doubling of the input voltage the total current draw would then be halved given the same wattage being consumed by the components, heaters, valves etc ... is that correct?

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