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Topic: AC adapter Hum ? |
Bobby Boggs
From:
Upstate SC.
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Posted 13 Aug 2001 8:25 pm |
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The AC adapter went bad on my dads Ibanez delay unit.So I carried the old one with me to Radio Shack.They matched the old one perfectly except for the fact the old one was 200ma.300ma was as close as they could get.They as well as others assured me that 100ma over would be no problem.
The problem,the Radio Shack adapter has a big time hum.I made sure to match the polarty tip to the unit.I've lifted all the grounds checked everything I know to check but still have a loud hum.However I borrowed a friends Ibanez adapter and the delay is as quiet as ever.What could be wrong here?As stated earlier the adapters are a perfect match except for ma. Thanks in advance!--------bb |
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Bob Brocius
From:
Lake Katrine, NY USA Don't blink, you'll miss it.!
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Posted 13 Aug 2001 10:35 pm
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Bobby, Ibanez equipment items have a "thing" about them that they require very clean DC voltage. Radio Shack power supplies are quite cheap and most of them do not have enough filtering. The hum you are getting is probably coming from the 60/120 cycle ripple that is on the output voltage of the supply. This ripple comes from rectifying AC voltage to pulsating DC and then not properly filtering it to make it true DC.
If the unit can be battery operated, try this and if the hum goes away, then my theory is correct. I had this very problem with an Ibanez AD-9 delay. To solve the problem, I went to Radio Shack and purchased parts and constructed a power supply that put out about 17 volts. Then I put a 9 volt voltage regulator across the output to clamp the final voltage down to 9 volts. Pure DC, no ripple, no hum.
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Bobby Brocius, ZumSteel D-10, 8x8, Blue, BL910 PUs
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Jack Stoner
From:
Kansas City, MO
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Posted 14 Aug 2001 2:23 am
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Many of the Ibanez units need a Regulated DC Voltage instead of the unregulated that most common power supplies (wall warts) put out. You either have to use the specified Ibanez unit or find a Regulated DC voltage unit.
I bought an Ibanez delay unit years ago and it required the regulated power supply. An Ibanez "gotcha" so you'll buy their higher priced power unit. |
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Bobby Boggs
From:
Upstate SC.
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Posted 14 Aug 2001 4:38 am
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| The Radio Shack adapter claims to be filtered but says nothing about being regulated.Anyone know a retailer that might have what I need? Thanks Bob and Jack!--------bb |
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