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Ampeg V4 original caps

Discussion in 'Amps and Cabs [BG]' started by jamaica, Aug 7, 2013.


  1. jamaica

    jamaica

    Feb 11, 2003
    Hi all,
    recently I bought this wonderful amp.

    Now I need to re-cap it, I made several researchs but I don't be able to find out the original caps value (especially the multicap section).

    Could You tell me the value of all of the original caps (including multicaps)?

    Thank You very much


    Best Regards
     
  2. coreyfyfe

    coreyfyfe Supporting Member

    Nov 19, 2007
    boston, ma
    Fliptops sells a complete recap kit for the V4 amps if you'd like to save the headache of trying to find the right ones.

    http://www.fliptops.net/catalog/cat-100016/capacitor-kit?page=2

    The can should say on the outside what the cap values are, the others should be similarly labeled.

    Looking at the power amp schematic I'd venture a guess that for the multi-section sets there's a 40/40/40 @ 450V and two 70/40 @ 450 along with a few others in there, another 40u/450V, a pair of 10u/100V and such.

    Looking at one of the fliptops packages, it looks like they sell it with a 40/40/40, 40/70, and 40/40/70 multi-sections all at 450V and a 47uf/450V single cap.
     
  3. AL30

    AL30

    Oct 15, 2009
    You don't really need the exact values. Get something close in capacitance and you'll be fine. Make very sure the voltage rating is enough.

    There is a lot of room inside those amps. You can rebuild inside on turret strips without much trouble at all and save some cash. It'll take a little more time than drop in replacements though. Pick your poison.

    The power section breaks down to 2x100uf in series (with a 100k 2W resistor across each), 2x40uf in series, and 3x50uf in in parallel (a 50/50 combo cap and a single).

    Here is the breakdown. It's on the wayback machine so I hope it works.

    http://web.archive.org/liveweb/http://www.geocities.ws/flintstudio/Re-cap_Ampeg_Amp.html

    If that doesn't work here is the original link http://www.geocities.ws/flintstudio/Re-cap_Ampeg_Amp.html

    While you're in there check your bias supply. I usually end up rebuilding the power supply and the bias supply just for peace of mind.

    AL
     
  4. A common change in the cap sections is to use F&T multi section caps and wire as the later year schem.

    http://www.ampegv4.com/images/schematics/Ampeg_VT-22_1977.jpg

    For C17 you can use a 40/40/40 CE can or (1) F&T 50/50 with a separate 50uf cap mounted above/near this in the chassis.

    C19 will be a 40 or 50uf cap in its normal place by the tranny and main circuit board.

    For C18 and C20 pick up a 50/50 F&T and a 100/100 F&T and wire per this diagram:

    v-4dualcanwiring.jpg

    http://www.ampegv4.com/forum/viewtopic.php?id=925

    And the normal disclaimer, if you are not familiar or experienced with working around high voltages, you should leave this to an experienced tech. Even caps that have been sitting in an unused chassis for years can hold a charge.
     
  5. jamaica

    jamaica

    Feb 11, 2003
    thanks all.

    Indeed 2 of the original multicaps were already change by a qualified technician that changed one 40-40-40/500 that was on the head (the original should be 40-40-40/450 or 475 from what You told me) and one 70-40-40/450 with new one (I think JJ brand).

    A friend of mine that works in the tubes and electronic world, told me that JJ caps arn't high quality, and is able to get better quality caps (he told me DALI brand)

    So i would like to know the correct value of the third multicap.

    From what I understand, it should be one 70-40-40/450, right?

    So the three multicap in the original circuit should be:

    One 40-40-40/450 or /475 or /500
    Two 70-40-40/450

    Is it correct?

    Thanks
     
  6. jamaica

    jamaica

    Feb 11, 2003
    Sorry,

    I "studied" the original circuit here:

    http://www.ampegv4.com/images/schematics/V4.jpg

    The original multicap should be:

    One 40-40-40/500 (C17)
    One 70-40/450 (C20)
    One 70-40-40/450 (C18)

    And then there is one single 40/450 (C19)

    Is it correct?

    thanks again
     
  7. coreyfyfe

    coreyfyfe Supporting Member

    Nov 19, 2007
    boston, ma
    Looks right. This schematic also has the 100u/100V bias cap but this may be two 10u/100V caps depending on the year of the amp (fliptops listing says the 100/100 was only on early models, see the schematic I linked above). Also don't forget the smaller value electrolytic caps in the preamp.
     
  8. I've never used JJ caps as I have heard the same.. I've talked to some who are not fond of the CE caps either, but I've used them without issue. I pick up F&T's when possible. Never dealt with Dali caps..

    While it is open it would be good to swap the bias cap. What do the other caps on the board look like? Yellow boxes?
     
  9. coreyfyfe

    coreyfyfe Supporting Member

    Nov 19, 2007
    boston, ma
    I used a mix of JJ, F&T, and Sprauge in my SC 120 and they've been great. Zero complaints with the JJs, and honestly I've never heard complaints about their caps. Their tubes certainly, but not their caps.
     

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