Any easy way to reduce mains from 122VAC to 110VAC?

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john65b

john65b

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Hey all, I have an ICEPower Module that will not turn on (sense) unless mains voltage is less than 110VAC. I have measured the mains here and I am around 122VAC.

I was troubleshooting the module and put it on a Variac. I noticed as soon as I got under 110VAC (min voltage for module is 85 VAC), the module ran perfectly. Also, once it is turned on, it ran fine on mains voltage of 122VAC.

I have put in a Current limiter (CL-90 - 120 ohm resistance), and didn't really help - I think it needs more Amps to get that ramp up in resistance / voltage to drop mains a bit.

Any other way?

By the way, this is an ICEPower 50ASX2 that has an internal SMPS onboard....
 
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Elvee

Elvee

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Joined 2006
john65b said:
Any other way?
Click to expand...
The simplest and most effective way is to use a low voltage transformer wired as an autotransformer.
In your case, a 120V/12V would do: since the regulation will work backwards, you'll get something like 116~118V with 122V input.
The power only needs to be the percentage of the voltage drop you need times the nominal power of your amplifier, ~10% in your case
 
S

simon7000

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Joined 2008
Elvee almost has it. Use a 120 to 12 volt transformer, wire the primary across the input voltage, place the secondary in series with the voltage to your power module. if you connect the secondary one way it will add 12 volts, the other it will subtract it. You only need a transformer with a secondary current rating equal to the final draw.
 
zigzagflux

zigzagflux

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Agreed, autotransformer is the way to go. Only slight change I would suggest would be to wire 120V and 12V windings in series with same relative polarity, then connect your line voltage to the entire winding, which will now be rated for 132V. You are placing fewer volts/turn on the transformer, which will allow it to run at lower saturation given your 122V input. Output will be around 110V, taken across the 120V winding.
 
john65b

john65b

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Yup. I agree. Works perfectly at 110vac. Like I said, once running from 110, I can raise to 122vac and no issues. Thats's why I was thinking of the CL-90.

I started out thinking it was a grounding issue (from other threads here on DIYAudio), but it repeatedly works perfectly with 110vac mains. I tried grounding both standoffs in corners (this is SE version), even tho the amp originally came with plastic isolated standoffs. Made no difference - it all came down to the mains.
 
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Mooly

Mooly

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Ken Newton said:
I would first contact ICE about the issue. It may be possible to easily adjust the over-voltage trip point of your modules to accept up to 125 volts without damage. That would be both the least costly and the most convienent solution of possible.
Click to expand...

+1

(can you determine the PSU chip set used and possibly look up data sheet applications to see how any overvoltage condition is determined)
 
Elvee

Elvee

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Joined 2006
john65b said:
I have a CL-90 (120R 2A) in there now...but I think the current draw it too low ... not getting a real drop on the mains - how do you reset the overvoltage?
Click to expand...
Series resistor (or thermistor) will lead you nowhere. Either you manage to alter the trip threshold in some way, or you change the input voltage in a fixed and reliable manner (not dependent on the current draw) and that's about it: every other solution will be a PITA in some way
 
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