Guitarsite Forums Guitar Discussion Guitar Digitech RP200 noise problem – no input signal

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  • #21629
    buck1107
    Participant

    Hi, I have a Digitech RP200 that only makes a hum when a cable is plugged into the input jack. There is no hum when nothing is plugged into the input. Could this be a bad input jack? It seems secure to the circuit board. Thanks, Louis

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    • #57438
      lee_UK
      Participant

      I need elevation to a new level, i need a new badge, just like they get in TGI Fridays, something that denotes my new status ‘RP200 fixer’
      are you reading this Mr Mod??

    • #57475
      1bassleft
      Participant

      Buck, looks/sounds like the bumhum is sourced. Well done, Lee – you can now press the moderators to label you “Lee – P.I.” -glitch investigator and licensed to drive hot cars through cardboard boxes in alleyways just for the visuals 😉

    • #57445
      buck1107
      Participant

      Lee, 1bassleft, thanks for the help in this!
      I tried the jam-along input, and it was OK. I fixed a cheap jack on a Peavey amp not too long ago, and it was the same type of 3 conductor, mostly plastic jack (cheeeeap).
      I’ll either go out and get a stereo jack or just wire in a mono jack and wire left and right together for a test to see if it works ok.

      [quote=”1bassleft”]Slight misunderstanding, Lee. I suspect the guitar input jack of the RP, not the jack socket on the guitar itself. Excellent call, though; the FX output jack is now ruled out. Buck, if you follow up Lee’s suggestion with the jam-along input (alone), and this is glitch-free, then it’s really got to be the instrument input jack. This takes more punishment than the rarely-used aux in.

      Even if the soldering to the input socket looks OK, I have a deep dislike of cheaply made jack sockets. The steel loses its elasticity and you may not have as good a sleeve contact as you’d like (and therefore no earth). If you have no hum from an aux input, a good Switchcraft 1/4″ on the guitar input could well solve the problem. As said, I’m no expert, but it fits in with bypass giving you the worst hum. The FX circuitry could filter out some of the hum frequencies you’re getting from bad earth.[/quote]

    • #57464
      1bassleft
      Participant

      Slight misunderstanding, Lee. I suspect the guitar input jack of the RP, not the jack socket on the guitar itself. Excellent call, though; the FX output jack is now ruled out. Buck, if you follow up Lee’s suggestion with the jam-along input (alone), and this is glitch-free, then it’s really got to be the instrument input jack. This takes more punishment than the rarely-used aux in.

      Even if the soldering to the input socket looks OK, I have a deep dislike of cheaply made jack sockets. The steel loses its elasticity and you may not have as good a sleeve contact as you’d like (and therefore no earth). If you have no hum from an aux input, a good Switchcraft 1/4″ on the guitar input could well solve the problem. As said, I’m no expert, but it fits in with bypass giving you the worst hum. The FX circuitry could filter out some of the hum frequencies you’re getting from bad earth.

    • #57450
      buck1107
      Participant

      I’ve tried the headphones, but the result is the same as the output jack – the humming is still there.
      2. I haven’t tried the “jam in” socket yet
      3. when I press both pedals together, it goes into bypass mode, although the humming is most pronounced like this (it’s apparent in some of the presets, not all, although no input signal is ever heard)
      4. the volume has been adjusted, but with no fix of the hum
      Thanks,
      Louis

      [quote=”lee_UK”]first of all, plug some headphones in the headphone socket, does the hum still happen? if the hum has gone then this suggests a problem on the output socket and not the input socket.
      2.do you get any hum when you plug a CD player in the ‘jam in’ socket?
      3.what about when you press both pedals together to get the bypass mode on? what happens? still humming?
      4. has the volume or level of the digitech at a sufficient level? you might have it set to 1 amd the amp up to 8, that would produce hum.[/quote]

    • #57484
      lee_UK
      Participant

      first of all, plug some headphones in the headphone socket, does the hum still happen? if the hum has gone then this suggests a problem on the output socket and not the input socket.
      2.do you get any hum when you plug a CD player in the ‘jam in’ socket?
      3.what about when you press both pedals together to get the bypass mode on? what happens? still humming?
      4. has the volume or level of the digitech at a sufficient level? you might have it set to 1 amd the amp up to 8, that would produce hum.

    • #57444
      buck1107
      Participant

      Thanks Lee.
      Yeah, I”ve checked it with a few different sources – guitar, bass, mic…different cables, etc.
      I’m beginning to wonder if even though the input jack tested ok (that it was going to the board ok), that it might have been a false reading. It sounds like the signal isn’t shoring to ground like it should…any thoughts?
      Thanks,
      Louis

      [quote=”lee_UK”]have you tried a different guitar in this unit too? Bass is pointing toward the guitar, im assuming you would have tried a different instrument or even a microphone just to rule out the hum? hum is usualy caused by a instrument lead shorting out, or as bass says an earth problem or short on the guitar itself.[/quote]

    • #57470
      lee_UK
      Participant

      have you tried a different guitar in this unit too? Bass is pointing toward the guitar, im assuming you would have tried a different instrument or even a microphone just to rule out the hum? hum is usualy caused by a instrument lead shorting out, or as bass says an earth problem or short on the guitar itself.

    • #57461
      buck1107
      Participant

      Thanks 1bassleft!
      I went back and inspected all of the jacks. As it’s a fairly recent construction, they’re mounted directly onto the circuit board. The jacks have the “spring type” contacts that snap tight against the plug once it’s inserted. They must be “normally closed” jacks.
      The solder connect points look clean and solid. I gave them all a firm tug, but nothing would wiggle. Perhaps I could resolder all of them just to test.
      I worked on a Peavey amp a few months ago that had the same kind of jacks, and a very similar problem – there was no signal, and the bad solder joint wasn’t apparent at first, although after resoldering, the signal was there.
      So, everything *looks* good

      [quote=”1bassleft”]Louis, please don’t mistake me for a sparky. I am not an electrics expert at all. That said, if the hum is atrocious in bypass mode (no decent output) and no output through the FX (but with reduced hum), doesn’t that suggest that you have lost earth, or ground, to the input jack?

      Solder-sniffers, please chime in; I’m only speculating here. Rather than spout bad theory (I do have a reason why I think this may be the cause), have a look at the ground wire to the sleeve connect of your RP’s input jack. Does it look flakey?

      Keep posting…[/quote]

    • #57460
      1bassleft
      Participant

      Louis, please don’t mistake me for a sparky. I am not an electrics expert at all. That said, if the hum is atrocious in bypass mode (no decent output) and no output through the FX (but with reduced hum), doesn’t that suggest that you have lost earth, or ground, to the input jack?

      Solder-sniffers, please chime in; I’m only speculating here. Rather than spout bad theory (I do have a reason why I think this may be the cause), have a look at the ground wire to the sleeve connect of your RP’s input jack. Does it look flakey?

      Keep posting…

    • #57440
      buck1107
      Participant

      [quote=”Farino”]http://www.digitech.com/ftp_mirror/PDFs/Manuals/RP200/RP200Manual.pdf[/quote]

      Thanks for the link!
      I went and reset the pedal last night, but it still makes the humming noise. In the “bypass”mode, it’s very loud, and in certain presets it’s noticeable, although not as loud as in bypass mode. No input signal can be heard.

      Are there any histories of faulty parts or things that go wrong the most with these 200s?

      Thanks,
      Louis

    • #57476
      Farino
      Participant
    • #57454
      buck1107
      Participant

      I’ve checked several cables with this effects unit, but the result is always the same, unfortunately. As I got this used, I don’t have the owner’s manual. Could you suggest somewhere online to get a free download of one?
      How likely do you think it is that it could be a burned out chip, or other component? I know that capacitors usually only go out after about 20 yrs, so that excludes them hopefully. The jacks feel solid on the circuit board. I would really like to find a site, etc that has detailed information on how to use a voltmeter to test components on a circuit board (or would one need a oscilloscope to do that?)

      Thanks again

      [quote=”lee_UK”]check your guitar cables, do they play ok from your guitar direct to the amp? try both cables, if the guitar plays ok with those 2 cables checked then i would go down the ‘factory reset’ route. Get the manual out and press the appropriate buttons to restore its defaults, you will lose all your user presets though, so make a note of what they are, it could be a faulty 1/4″ input jack on the RP200 but i think its unlikey, try the other options first then get back to the forum.[/quote]

    • #57442
      lee_UK
      Participant

      check your guitar cables, do they play ok from your guitar direct to the amp? try both cables, if the guitar plays ok with those 2 cables checked then i would go down the ‘factory reset’ route. Get the manual out and press the appropriate buttons to restore its defaults, you will lose all your user presets though, so make a note of what they are, it could be a faulty 1/4″ input jack on the RP200 but i think its unlikey, try the other options first then get back to the forum.

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