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Just bought a GK-MB2 lightweight head and it didnt work..

L

littlewayne0

Dec 11, 2008
12
0
#1
Hi all,

Does the power supply effect gk head since the plug itself is Americans standard and I have to use a converter in order for me to use it in the Uk.

I pluged it into the converter and turn it on but all I heard was the fan spinning rapidly for one second and thats it, it died out..

What should I do now? Did the voltage difference or the converter burn out the head or something..?

ps Ive used my Backline plug in (Uk standard) and it didnt work as well so I am assuming it is the machine..

Im gonna burst into tears now gigs coming up and wasted money
Help me please...
should I return it or try to fix it?

Thanks,
Wayne
 
#3
Hi Wayne.

The model of the converter?

AFAIK some GK heads have multitapped transformers for switching the supply voltages, and some use SMPS supply sections which can be used with any wall voltage.

Edit: After searching for the head, everything indicates a SMPS supply, so it should perform well with or without the converter. Unless You plugged the converter the wrong way around and fed the amp 480V. That should have put it into protection mode though, not ruin it.

The fan spinning like a jet engine and then dying doesn't sound too good though, I'd take the head to a tech for a once over.

BTW, blowing a head and then trying to return it would not be cool.

Regards
Sam
 
#5
just a thought - doesn't stuff from US run on 110 volt ? and UK stuff on 230 ? - even with the converter (which I guess just changes the plug you put into the wall) that would be 2 times with the PSU can handle - thus making the jet noise and die sounds probable. Some of those PSU's has a switch on the back or inside that switces from 110 to 230 - could that be it ?

in my experience ( with a computer PSU) the protect circuit got fried as well.
 
#6
Hi.

crusie said:
just a thought - doesn't stuff from US run on 110 volt ? and UK stuff on 230 ? - even with the converter (which I guess just changes the plug you put into the wall) that would be 2 times with the PSU can handle - thus making the jet noise and die sounds probable. Some of those PSU's has a switch on the back or inside that switces from 110 to 230 - could that be it ?

in my experience ( with a computer PSU) the protect circuit got fried as well.
Click to expand...

People who insist on using el equipment of a different wall voltage requirement than what's generally available, use stepper transformers.

For some regions it's a step-up transformer which rises the voltage 110->240 for example. That would be used if European gear is used in USA.

For some regions/equipment it's a step-down transformer which drops the voltage from 240->110 for example. That would be used if an US standard appliance is used in Europe.

The transformer can be an auto transformer, isolating transformer or a regular transformer depending of the requirements. There may even be some SMPS converters around for lower power requirements.

Choosing a sturdy enough transformer is absolutely critical, 50% capacity just won't cut it, it has to be at least 100%.

If the converter is a plug style, it just changes the pinout, not the voltage.

AFAIK, no SMPS requires the voltage to be pre-set, but it's always possible.

Regards
Sam
 
#7
Hi Sam! :)

I have seen many switch mode supplies that have to be physically switched to change supply voltages. Some have an actual switch while others have a jumper or a movable link. I know nothing about the GK but their website or customer service should be able to give the proper procedure. I would also conclude that if the amp was plugged into double the voltage it was expecting that it would blow.

OP, as Sam stated if a step up/down transformer is required it has to be sized at greater than the output power of the amp. For a 500W amp use a 750VA or so transformer, 800W amp, 1000VA etc. Big heavy and fairly expensive I would think.

Paul
 
#8
crusie said:
just a thought - doesn't stuff from US run on 110 volt ? and UK stuff on 230 ? - even with the converter (which I guess just changes the plug you put into the wall) that would be 2 times with the PSU can handle - thus making the jet noise and die sounds probable. Some of those PSU's has a switch on the back or inside that switces from 110 to 230 - could that be it ?

in my experience ( with a computer PSU) the protect circuit got fried as well.
Click to expand...

The modern way of doing AC to DC is two have a universal rectifyer. These are mass produced bricks that run on 50/60Hz from 88-264VAC. This allows them to work in Japan at the lowest line levels and the UK which have the highest line levels and everywhere in between. When I say modern, this technique has been mass produced for more than a decade.

Did they use this approach in the MB2? Not sure. I would suspect that anyone designing a new product would seriously consider this approach. On the other hand, there are compromises to be made by having to deal with high current at low line and high voltage at high line. So if optimzation is chosen over convenience and flexibility, there may be a need to change some internal setting when going from a low line system to a high line one.

Editted to add: The GK MB2-500 manual says that you need to have the proper line voltage configuration. So if you took a US unit and plugged it into a European Outlet, you probably let out the magic smoke.
 
#9
Can we put this topic in the FAQ already? Unless the manufacturer specifies universal power supply it's generally a bad idea to use an amp designed for the different AC standard with step up/down transformers. You lose efficiency, may limit the power output and possibly overheat the amps power transformer (linear PS) due the difference in line frequency.

Looks like a repeat of http://www.talkbass.com/forum/showthread.php?t=55835
 
#10
Hi.

BassmanPaul said:
Hi Sam! :)

I have seen many switch mode supplies that have to be physically switched to change supply voltages. Some have an actual switch while others have a jumper or a movable link. I know nothing about the GK but their website or customer service should be able to give the proper procedure. I would also conclude that if the amp was plugged into double the voltage it was expecting that it would blow.

Paul
Click to expand...

Thanks Paul.
Since the stuff I'm most familiar with is usually designed for international use, I automatically assumed that auto-sensing the input voltage is more commonplace. Unfortunately it seems that in MI gear it isn't.


WingKL said:
Can we put this topic in the FAQ already?
Click to expand...


Just one question?

Who reads the FAQ?

Since under-/overpowering a cab and tube vs. SS and "can I paly my bass through a guitar amp" pops up weekly, I doubt that this topic would be any different :D.

A very good suggestion in any case, I do't deny that.

Regards
Sam
 

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