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SVT-VR Woes

Discussion in 'Amps and Cabs [BG]' started by Juan Grande, Mar 7, 2008.


  1. Juan Grande

    Juan Grande

    Mar 7, 2008
    Can any of the SVT-VR vets take an educated guess on this issue?

    I have a new (six months old) SVT-VR head and a 610. Last week, in setting up for a gig, I could not get a green light when I came out of standby. After what seemed like 20-30 minutes of futzing, the light suddenly went green and the head performed like a champ. The change in status did not seem related to anything I did.

    Today, six days later, I went to rehearse for the first time since the show. The volume output of my rig is suddenly greatly reduced (maybe down as much as 70-80 percent) and the tone quality is significantly distorted.

    I let the rig warm up for several hours with no improvement. Has anyone seen this? Can any guess what my issue might be?

    Thanks
     
  2. JGR

    JGR The "G" is for Gustav Supporting Member Commercial User

    Jun 29, 2006
    Maryland
    President, CEO, CFO, CIO, Chief Engineer, Technician, Janitor - Reiner Amplification
    i believe there is circuitry built into the amp to prevent you from taking it out of standby and operating it without the tubes being properly heated. the circuitry has had some issues "sticking" for lack of a better word. other folks have had similar experiences. you probably just need a new relay or whatever component it is in that circuit.

    JR
     
  3. I had the same problem with mine before I returned it and got my money back.

    The tech guy where I bought it just played with the tubes and made sure they were all in place properly and he claims it now works fine.

    I don't know. It's not mine anymore. But its worth a try.
     
  4. If the volume is low and distorted, there's something wrong inside. I wouldn't run it anymore - get it to a tech and have it looked over.

    Is it still under warranty from Ampeg?
     
  5. nysbob

    nysbob

    Sep 14, 2003
    Cincinnati OH
    That relay/delay business seems to be a lot more trouble than it's worth. I can't understand why they elected to go that route.

    If you can't understand power up sequence on a tube amp, maybe you shouldn't have one. :eyebrow:
     
  6. main_sale

    main_sale

    Apr 26, 2004
    Cape Cod
    Could be something as simple as a bad tube.
     
  7. kdogg

    kdogg

    Nov 13, 2005
    Ohio
    +1

    Have a qualified tech check your tubes for sure. My CL just did a very similar thing, and it turned out to be a blown power tube, that also took out a resistor.

    By the way, the amplifier is still under warranty, yours would be too, and Ampeg took care of everything. Their customer service was excellent.
     
  8. Jerrold Tiers

    Jerrold Tiers

    Nov 14, 2003
    St Louis
    Won't likely be a bad tube.........

    The CL has a "protection" circuit in it that works with that relay.

    The VR has a pure and simple time delay, no protection. There is a secondary function as a cutoff for very low mains voltages.

    Could be that either:

    1) the low mains cutoff is set wrong, due to bad part, or possibly even a design that is too "tight" on the spec.

    2) Could be that there is a bad solder joint in the circuit that just opens and makes it not pull in the relay.

    I kinda lean toward the bad solder... Not only is it not a rare thing, but also, the recent mandates for "no-lead" solder have meant a completely new set of soldering problems. Leaded solder performs in many ways better, and is easier to get "right", and many companies are still struggling with solder issues even now 2 years after the rules became effective.
     
  9. kdogg

    kdogg

    Nov 13, 2005
    Ohio
    If I'm understanding you correctly JT, the above would explain the unit not coming out of standby, but would it explain the amp coming out of standby and "The volume output of my rig is suddenly greatly reduced (maybe down as much as 70-80 percent) and the tone quality is significantly distorted"?

    I ask this because my CL did that exact thing after having some earlier issues with going into, or not coming out of, standby, ending with the volume and tone issues the OP describes. One of my power tubes had blown, and took out a resistor of some sort.

    Please do not take this as questioning the validity or logic of your diagnosis JT. I have immense respect for both your experience and opinions. :)
     
  10. Jerrold Tiers

    Jerrold Tiers

    Nov 14, 2003
    St Louis
    The relay takes out the mains power to the high voltage, the bigger transformer of the two power transformers.

    So if volume is reduced, but not "gone" there must still be high voltage, and the relay is still connected.

    For volume "drops" etc, probably anther issue entirely, unless the volume drop is very short, similar to the time it takes sound to disappear if you flip the standby while you are playing.

    I should make the previous statement clearer..................

    When I said "not likely to be a bad tube" I referred to the OUTPUT tube fault idea as suggested by the example of the CL protection cutting out when a power tube is bad.

    In other words, the relay will not open for a bad output tube the way the CL does, so that isn't what is causing it to open (if it is opening).

    It surely could be some other tube problem, or more likely a bad solder joint / bad connection
     

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