1. Please take 30 seconds to register your free account to remove most ads, post topics, make friends, earn reward points at our store, and more!  
    TalkBass.com has been uniting the low end since 1998.  Join us! :)

Carvin R-600 acting up

Discussion in 'Amps and Cabs [BG]' started by Captain Awesome, Jan 2, 2003.

  1. Captain Awesome

    Captain Awesome

    Apr 2, 2001
    The preamp section on my series II Carvin R-600 occasionally decides to mute the output or make it really weak and distorted. It usually only happens for a few seconds and then it goes back to normal but still, I don't want this kind of performance. It's got to be some sort of loose connection somewhere but I can't figure out what. Has anyone else had this problem before and/or know what it might be?

    BTW, I had it fixed a few months ago for doing something similar, except it became like that all the time (unusable) so the repair guy apparently secured a bunch of contacts and it worked perfectly until now.
  2. SCH


    May 3, 2002
    San Antonio, Texas
    I've got a series III R-1000, and it does what you are describing when it's being bridged into cabs it doesn't like. Wierd, huh? For example, I can bridge it into a single 8 ohm Bag End S-15D without any instability, but when I try and bridge it into both of my Bag End S-15D's (4 ohm load) it gets flakey and kind of cuts in and out. My R-1000 is solid in all other respects, but what good is it if I can't bridge it into the cabs I want? Answer: Got a new head on order (not a Carvin). I'll use the Carvin as a backup.
  3. SRSiegel

    SRSiegel Guest

    Sep 17, 2001
    Ann Arbor, Michigan
    i have a series 2 R600, but i havent had any problems with it. I do know however, that all of Carvin's amps are all component based, meaning if something goes bad, they can just unplug the bad component and put a new one in. This means there are a bunch of plugs in the amp that could (unfortunatly) vibrate loose. you might wanna just check and see if one of those plugs is bad. I dont know if yours is still underwarranty or not... or if that will void the warranty. you could also call carvin and tell them this, they might say the same thing. when a preamp died on my LB75 then just sent me one and let me do the repairs myself, and it didnt effect the warranty. best of luck.
  4. Gabu


    Jan 2, 2001
    Lake Elsinore, CA
    Could that be the noise gate kicking in real strong? It sounds to me like what would happen when I turned the noise gate on.
  5. If you have a series II, then those have a real tube in the preamp section. Have you tried replacing the tube??

    I have had amps in the past that flaked out from time to time, and changing the tube worked.
  6. chucko58


    Jan 17, 2002
    Silicon Valley, CA, USA
    I paid for all my gear myself. Well, me and MasterCard.
    Carvin stuff is good bang for the buck, but one of the places they save money is on connectors.

    Sounds like your amp could use some "deep tissue massage". Get some good contact cleaner (my favorite is Caig DeoxIT D5), pop the amp open, and apply the contact cleaner to every connector you can find. Disconnect and re-connect every connector several times to make sure it's making good contact.
  7. Captain Awesome

    Captain Awesome

    Apr 2, 2001
    The problem with mine is definitely in the preamp, the power amp is fine.

    The head has two independent first gain stages, one is solid state and the other is a tube, and they can be selected or mixed with a knob. The problem can kick in even when the knob is all the way to solid state. So I don't think the tube could be the problem.

    That's most of what the repair guy did when I took it into the shop last time so I think I'll try it myself this time. I bought the amp used on Ebay so the warranty's not an issue. Anything I should be careful of when I do this?

    Gabu-- I always leave the noise gate off.
  8. For the price of a 12AX7 tube, I would change it anyway if you open her up. I have the series II R1000, and to date have not had a problem. However, I picked up a used NightBass SGX dirt cheap that was supposed to have issues.

    When I first tried it out, it would cut in and out, and had volume issues (up and down). This unit, like the Carvins have a blend on the preamp section. It did as you say even when all the way blended to the SS side. Replacing the tube seemed to do the trick, so you never know.
  9. Captain Awesome

    Captain Awesome

    Apr 2, 2001
    I guess the circuit could be wired that way, but it would be hard for me to tell now since so far today it's worked perfectly. But I think I'll try that if it starts malfunctioning again.
  10. Captain Awesome

    Captain Awesome

    Apr 2, 2001
    Bumping this thread up because I plan on working on my amp today, and would like suggestions.

    An overview of what's going on with my amp:

    ** It's a Carvin R600, Series II

    ** The output occasionally cuts out and sounds weak and distorted, then goes back to normal after a minute or two.

    ** The problem is definitely not in the power amp. The power amp is fine.

    ** I can't predict when it's going to happen, sometimes it will run for hours without any problems

    So far I've cleaned the tube prongs and the return jacks, neither did anything. (I would like to find out exactly where the problem is.)
  11. Richard Lindsey

    Richard Lindsey

    Mar 25, 2000
    Metro NYC
    Good luck. Since changing the tube is such a cheap thing to do (< $10), I'd try that even if you don't think it's the problem. Maybe also try cleaning the input jacks and checking the connections, unlikely as that may seem, as long as you're going to be going inside the amp anyway.
  12. Denimhorn


    Nov 25, 2002
    i got my eyes on this post primusdude....as you know i still got the same problem. I am going to call Carvin tomorrow i think.
  13. Captain Awesome

    Captain Awesome

    Apr 2, 2001
    Cool, keep me updated if they have an idea.
  14. Captain Awesome

    Captain Awesome

    Apr 2, 2001
    It's definitely not the tube. I replaced the tube and nothing's changed.

    So I think I'm going to attempt to do what this guy did to fix a similar problem on his R600 (reheat some solder connections and/or clean the pushbutton switches):

    Now, a dumb question: How would I remove the circuit board to do that, and how would I get it back in?
    (Edit: I've got it now, just unscrew and remove the nuts around the jacks and it'll come out)
  15. Captain Awesome

    Captain Awesome

    Apr 2, 2001
  16. Captain Awesome

    Captain Awesome

    Apr 2, 2001
    Something I did 4 days ago seems to have fixed the preamp, I cleaned the input jacks (don't think that was the problem though) and I also took out the circuit board in back and put it back in. I'm guessing something related to doing that secured whatever connection was going bad.

    So far it's been working great, and it's been played through for about 6 hours since then.
  17. Denimhorn


    Nov 25, 2002
    I have an update on my situation as well. I played through my entire setup (both cabs) this last weekend (for about 8 hours) at high levels. I didnt have any problems....but the reason why is because I was playing in bi-amped mode. Looks like the problem really only is with the full-range mode out of the high-frequency output in the back.

    I only get the signal distortion/loss problem when i play the 2x10 in full-range mode out of the high frequency.

    So Primussdude...you didnt even do anythign else other than remove the circuit board and put it back in?
  18. Captain Awesome

    Captain Awesome

    Apr 2, 2001
    I'm guessing I had a bad connection with one of the thin black ribbons inside the amp, and somehow it was jostled into place.

    Your amp definitely has a different problem then what my amp had, but I bet it has something to do with one of the black ribbons. If you haven't done this already, I would suggest cleaning the connectors for those black ribbons on the routing (jacks) board in the back. I've never actually taken one out of its socket so I don't know if there are any complications with doing that, but you definitely have to take out the board first, since those ribbons connect on the other side of the board.
  19. Denimhorn


    Nov 25, 2002
    right on...i will give that a shot man.

    How tough is it to pull that board out? I already cleaned every connector that i could without removing anything per suggestions on this forum - wasnt very hard at all. Any tips or concerns i should be aware of?
  20. Captain Awesome

    Captain Awesome

    Apr 2, 2001
    Well I think that was a fluke, today I got it to not work. Shows how intermittent the problem is.

    The problem with my amp is really weird. It seems to be much more likely to cut out when it's cold. I think movement's a factor, I've been able to get it to cut out by shaking it, but that was only once.

    Here's the really weird thing: when it is in cutting-out mode, I can get it to 'fix' itself by giving it a very high signal (smacking the bass strings.) It makes a loud 'snap' and then works perfectly for quite a while after that. I don't think sound vibrations cause that because when the preamp is malfunctioning, the output is VERY low. It leads me to believe it might not be a connection problem after all.

    For the routing board in the back, first you need to use pliers or something to take out the plastic nuts surrounding the jacks on the back panel. Rotate them a 1/2 turn and then pull them out. Then the board can come out easily. The power ribbon has a big connector so it's easy to take out. The preamp ribbons (black with white side wire) have smaller connectors... I don't know what's involved in taking them out/putting them back in.

    I plan on having a repair guy look at it in the near future.