Digitech RP355 Processor : Voltage Query for usage in India.

Discussion in 'Guitar Gear Talk Forum' started by neonazure, Oct 23, 2011.

  1. neonazure

    neonazure New Member


    I have recently picked up a Digitech RP 355 from the US and it is presently being sent to me in India.

    The Power Adapter that comes with in the box has the following readings.

    Input '120V ~ 60Hz 18W'
    Output '9V ~ 1.3A'

    I would like to know will I need a 'step up transformer' for using the Processor in India?
    If someone has an RP 355 which you've picked up from India, could you please share the Input & Output readings on your adapter?
  2. dyorel

    dyorel New Member

    Hi, its not just the voltage that needs to be stepped up, the frequency differs too, making the transformer expensive.

    Look for a 9V 1.3 Amp adapter in India. A higher current rating (>1.3 Amp but within a safe limit of 2.5 Amp) will easily power the processor. Going below 1.3 Amp may not power it up.

    Check your manual for the current drawn by the unit, and you can buy the adapter based on that.

    And dont risk the unit with cheap adapters from your local electronics store. Look for adapters that meet your specs from music stores. Else build one from this Fixed Voltage Power Supply :) (Im an electronics geek)
  3. alpha1

    alpha1 I BLUES!

    Dyorel, I don't think frequency is going to play any role: in a rectifier circuit, it makes no diff whether the AC is on 50Hz or 100Hz.

    Neonazure - what does your adapter say about input?
    If its switched mode unit - then it has the ability to take in vast variation in voltage. Switched mode units don't operate like regular step down transformers + rectifiers.

    Examples of switched mode = Computer power supply, mobile rechargers, laptop rechargers - all are small sized and can take in a wide variation of volatage like 110 to 250 V.
  4. dyorel

    dyorel New Member

    @Alpha 1

    230V 50Hz ->Transformer -> 110V 60 Hz -> RP 355 adapter....Unless the 355 adapter works off 50Hz, wont give the best output...Getting geeky, but the adapter transformer coil impedance will change with frequency, so the transformer should step up 50 to 60 Hz

    But you're right, switched mode supplies will work, but he'll have to do jugaad to get the correct pin....Again may prove to be expensive.

    Cheapest option is to buy a adapter here. Bajaao has one, but current limited to 1A, may or may not power the 355.

    Cheaper still will be the build :)

    (Building my own tremolo, fuzz and compression pedals, and my own power supply for them....Hope the build turns out well, will post pics/vids)
  5. shriworld4u

    shriworld4u New Member

    Its a diffrent thing for the laptops.. They hv a wide range 110-220v..
    I hv a Rp70.. Yup you will require a step down transformer..Thats it..nothin else..jst make sure u get a good brand.. Othrwise you may end up spoiling the processor.
  6. alpha1

    alpha1 I BLUES!

    How much? And what will be its effect on voltage available across the pins?
  7. dyorel

    dyorel New Member

    erm.....difficult to calculate but impedance increases with frequency, so will the heating effect and may burn out the coils.

    I guess you missed the part that 50 or 60 Hz isnt directly given to the rectifier, it goes through a transformer in the RP355 adapter, then rectified.

    check out Transformer - Wikipedia, the free encyclopedia effect of frequency section in case you doubt it.
  8. neonazure

    neonazure New Member

    Thanks for all your replies. I got a step down converter and it works like a dream.
  9. alpha1

    alpha1 I BLUES!

    I didn't miss it.
    I asked what would be the potential drop/gain due to change from 60Hz (design) to 50Hz (operating).
    This would be reflected in the DC side pins after step down and rectification.

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