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Carvin B1500 stuck in protect mode

Discussion in 'Amps and Cabs [BG]' started by askani19, Apr 30, 2018.


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  1. askani19

    askani19

    Feb 19, 2015
    Philadelphia
    Hey guys. I have a B1500 bass head. Home use only. Never play with it above 5. Last night it started clipping and then went into protect mode. It will power on but no sound out. Has anyone encountered this? Any ideas?
    I emailed Carvin and they sent me an email back saying
    "Our service and parts department that handles your model has been closed down. Parts are sold out and discontinued. We sincerely apologize for the inconvenience."
     
  2. Yeah! Carvin is D.O.A.

    Have you tried firing up without speakers and speaker cables connected to the amp?
    This is usually OK to do with SS output amps.
    Doing this would eliminate the possibility of any bad speakers or speaker cables from being the culprit.
     
  3. BasturdBlaster

    BasturdBlaster

    Feb 19, 2012
    Crandon WI
    Ribbon cable cleaning?:nailbiting:
     
    Bill Whitehurst and BassmanPaul like this.
  4. Try linking the Send and Return of the Effects Loop with a signal cable and see if that helps.
     
    BasturdBlaster likes this.
  5. askani19

    askani19

    Feb 19, 2015
    Philadelphia
    I have not opened the head up as of yet.

    Things I have tried
    Different guitars
    Different cable from guitar to head
    Different cable from head to cab
    Different cab
    Connecting the effects loop

    As soon as there is a connection from guitar to head the protection light immediately comes on. If I touch the guitar side of the cable with my thumb the head goes into protection.
     
  6. askani19

    askani19

    Feb 19, 2015
    Philadelphia
    So inside there are a few questionable solder spots, specifically 2 diodes and a couple of the resistors. Nothing looks toasty or broken. However there is one ceramic that is much hotter than the rest. So for some reason that one is getting more current than the rest.
     
  7. BadExample

    BadExample

    Jan 21, 2016
    Injiana
    If you connect an active bass to the effects return does it work?

    Try a different outlet?
     
  8. If you don't have a schematic, but might know what you are doing,
    that hot resistor is probably feeding the problem.
    Can you follow the traces on the board?
    Any burned or brown areas of the board?
     
  9. askani19

    askani19

    Feb 19, 2015
    Philadelphia
    Haven't pulled the board out yet. I have a background in arcade and pinball repair so I can get around a PCB. Nothing looks burnt. None of the caps are swollen. No obvious breaks in anything. Couple of suspect solder joint to the eye but any of them could be failing.
    Half of these components are surface mount though so that might be an issue. Just need to narrow down what is failing. Maybe do a reflow of everything to start.
     

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