Capacitor leak on my GK 800RB

Discussion in 'Amps and Cabs [BG]' started by jeyvi, Dec 26, 2005.

  1. jeyvi


    Dec 21, 2005
    i thought my power transformer smoked. when i plugged it again and opened the cover. after 3 seconds one of the 470uf 63v capacitors emitted smoke. it has leak!

    will it be possible to order a capacitor here in the GK site store?

    if i can get the capacitor here... is it ok if i only change the one with a leak or i have to change all 4 capacitors?

    and... there's a capacitor with the same values but its a vertical one. but the one on the 800RB head is a horizontal type capacitor.
    will it be ok if i replace it with a vertical type?

    i need your help GK guys ASAP!

    thanks very much!!!
  2. jeyvi


    Dec 21, 2005

    i've replaced the one that leaked. and i plugged it to see if it works. then again... after 3-5 seconds... the other 3 capacitors smoked!

    now i dont know whats causing them capacitors to blow and smoke.

    im afraid if i replace all 4. the other 4 bigger capacitors might get smoked as well.

    theres no service center here... so i'll probly just have it checked by a good technician.

    damn... i havent even used the amp yet.

    thanks very much
  3. Trevorus


    Oct 18, 2002
    Urbana, IL
    As long as voltage vlaue and capacitance are the same, you should be just fine. Also, make sure that the polarity is right. Then also make sure that they won't short out. I personally would replace all of them, just to be safe.
  4. jvb


    Jul 11, 2005
    Canberra, Australia
    The capacitors have smoked/vented probably because too much current has been drawn through them. I would be looking at the output stage, I would say that one of the output transistors/fets has shorted. Get it checked by a technician.
  5. Did you unhook your power transformer when you were intially checking the amp out?
  6. ras1983


    Dec 28, 2004
    Sydney, Australia
    +1. if you don't really understand the problem, don't risk further damage by attempting to repair it yourself. have an experienced tech look at it.
  7. +1. Its not a capacitor problem... well, now it is :) But there's something else in there causing them to go.

    - Andrew
  8. fdeck

    fdeck Supporting Member

    Mar 20, 2004
    Madison WI
    HPF Technology: Protecting the Pocket since 2007
    If the bridge rectifier has one or more shorted diodes, you could be feeding AC to the capacitors, which would cause release of the magic smoke as described. Or it could be a good old fashioned electrical short due to crossed wiring etc.
  9. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    My bet is that the diode bridge is toast, but that could have been caused by problems further downstream. You have to check out everything and you need schematics, tools and experience to do it. Shop time.
  10. jeyvi


    Dec 21, 2005
    turns out the amp is 110V and i plugged it in a 220V socket which is what we use here. the technician said since it came from the US... its definitely 110V.

    thats why the 470uf 63v capacitors smoked... now its all working great! i can now get the hartke cab!

    one question though...

    it says in the manual if i were to use a 220V operation. i can just change the fuse to a type 3AG4A Fuse.

    i cant find an exact type. just a 4A fuse. w/o the 3AG.

    will that work?
  11. fdeck

    fdeck Supporting Member

    Mar 20, 2004
    Madison WI
    HPF Technology: Protecting the Pocket since 2007
    I think 3AG simply refers to the size of the fuse, so if the replacement fits, it is probably OK. It might be worth contacting GK to ask them if it is a "fast" or "slow" type fuse.
  12. jvb


    Jul 11, 2005
    Canberra, Australia
    Yup, that'll do it. :rolleyes:

    3AG refers to the size of the fuse. If you can't find out whether you need fast blow or slow blow, grab a couple of each, rememer which is which, and try a fast blow first. If you find they keep blowing at power on then try the slow blow. Don't go over the 4amp rating tho'.
  13. jeyvi


    Dec 21, 2005

    so if i put them 4A fuse i can now plug my 800RB on a 220V socket?
  14. tadawson


    Aug 24, 2005
    Lewisville, TX
    A fuse change will NOT alter what voltages the amp is built/setup to accept! Read the back of the amp and see what voltages it is rated to take, and see if there is a voltage selection switch. My guess would be that since it is a US amp, that it CANNOT take 220V without internal modifications, if that is even possible. . . . or if all else fails, call GK and ASK.

    - Tim
  15. jeyvi


    Dec 21, 2005
    Located on the rear panel, never operate this amplifier with any
    other than the recommended fuse :
    115V operation - replace with Type 3AG7A
    230V operation - replace with Type 3AG4A

    this is what it says in the manual of the 800RB.

    so is it possible?
  16. Trevorus


    Oct 18, 2002
    Urbana, IL
    You need to have a tech change one of the transformer wires. Then you change to fuse, since the amp will use less amps at that higher voltage.
  17. jonly


    Oct 3, 2005
    Springfield, il
    I sent my 800rb in three weeks ago. It cost 88 bucks for repair and is on its way back now. You can't beat that.
  18. jeyvi


    Dec 21, 2005
    damn... if only there's a service center here for GK. but since i got it from the US. there's none.

    whats the proble with your 800RB dude?