The Dynaco Tube Audio Forum

Dedicated to the restoration and preservation of all original Dynaco tube audio equipment - Customer support for Dynaco VTA tube amp kits, all Tubes4hifi.com products and all Dynakitparts.com products


    VTA board and parts placement..... :}

    Share

    wolverine

    Posts : 60
    Join date : 2010-02-20

    VTA board and parts placement..... :}

    Post by wolverine on Thu Mar 25, 2010 10:48 pm

    When I purchased my VTA board "assembled" from Roy I never got a drawing of the board and the parts placement on the board. Is there an available drawing that would give me this information, such as the photo Bob posted of the original parts layout for the 7199 board?

    wolverine

    Bob Latino
    Admin

    Posts : 2414
    Join date : 2008-11-26
    Location : Massachusetts

    Re: VTA board and parts placement..... :}

    Post by Bob Latino on Fri Mar 26, 2010 6:09 am

    wolverine wrote:When I purchased my VTA board "assembled" from Roy I never got a drawing of the board and the parts placement on the board. Is there an available drawing that would give me this information, such as the photo Bob posted of the original parts layout for the 7199 board?

    wolverine

    Wolverine,

    The parts placement on the VTA driver board is below. The photo is of the older version of the board. The only difference is that on the newer version there is no C9 or C10. There are two versions of the board. The standard gain and the lower gain version. The parts list of both is below. The part numbers are Mouser Electronics part numbers.

    Bob





    Standard gain board with three 12AT7 tubes
    ITEM VALUE QTY PART#
    PCB 1 VTA ST70
    R5 & 6 100 2 273-100-RC
    R27 & 28 1K 2 273-1K-RC
    R9 & 10 2.2K 2 273-2.2K-RC
    R7, 8, 15, 16 7.5K 4 273-7.5K-RC
    R1,2,39 10K 3 273-10K-RC
    R17 & 18 12K 2 273-12K-RC
    R37 & 38 27K 2 273-27K-RC
    R19 - 22 51K 4 273-51K-RC
    R11 & 12 68K 2 273-68K-RC
    R13 & 14 150K 2 273-150K-RC
    R3, 4, 29-32 270K 6 273-270K-RC
    R23-26 1M 4 273-1.0M-RC
    R40-43 10 1w 4 281-10-RC
    R44 2.2K 2w 1 282-2.2K-RC
    V1-3 12AT7 3 AES JJ 12AT7
    VS1 - 3 9p pcb 3 AES P-ST9-215
    VR1 - 4 50K 4 72-T20YP-50K
    VR5, 6 10K 2 72-T20YP-10K
    C11 & 12 220 pF 2 5982-15-500V220
    C13 - 16 22uF 450v 4 140-XRL-450V33-RC
    C17 100uF 100v 2 140-XRL-100V100-RC
    D1 UF4007 1 512-UF4007
    C1 - 4 .10 400v 4 AES C-PD10-400
    C5 - 8 .22 600v 4 AES C-PD22-600


    Lower gain board with three 12AU7 or 12BH7 tubes
    ITEM VALUE QTY PART#
    PCB 1 VTA ST70
    R5 & 6 100 2 273-100-RC
    R27 & 28 * 470 2 273-470-RC
    R9 & 10 * 1K 2 273-1K-RC
    R15 & 16 * 6.8K 1w 2 281-6.8K-RC
    R7 & 8 7.5K 1 27.-7.5K-RC
    R1,2,39 10K 3 273-10K-RC
    R17 & 18 * 12K 2w 2 282-12K-RC
    R37 & 38 27K 2 273-27K-RC
    R11-14, R19 – 22 * 33K 2w 8 282-33K-RC
    R3, 4, 29-32 270K 6 273-270K-RC
    R23-26 1M 4 273-1.0M-RC
    R40-43 10 1w 4 281-10-RC
    R44 2.2K 2w 1 282-2.2K-RC
    V1-3 12AU7 or 12BH7 3
    VS1 - 3 9p pcb 3 AES P-ST9-215
    VR1 - 4 50K 4 72-T20YP-50K
    VR5, 6 10K 2 72-T20YP-10K
    C11 & 12 220 pF 2 5982-15-500V220
    C13 - 16 22uF 450v 4 140-XRL-450V33-RC
    C17 100uF 100v 2 140-XRL-100V100-RC
    D1 UF4007 1 512-UF4007
    C1 - 4 .10 400v 4 AES C-PD10-400
    C5 - 8 .22 600v 4 AES C-PD22-600

    wolverine

    Posts : 60
    Join date : 2010-02-20

    Thanks Bob... :}

    Post by wolverine on Fri Mar 26, 2010 8:42 am

    I sure appreciate it Bob, thanks. This may go a long ways to helping me solve my problem.

    wolverine

    wolverine

    Posts : 60
    Join date : 2010-02-20

    I may have found something here on the VTA board.....

    Post by wolverine on Fri Mar 26, 2010 12:12 pm

    All of the caps underneath the board are .22, this does not seem to be correct according to the parts list from Bob. Anyone?

    Thanks
    wolverine

    Bob Latino
    Admin

    Posts : 2414
    Join date : 2008-11-26
    Location : Massachusetts

    Re: VTA board and parts placement..... :}

    Post by Bob Latino on Fri Mar 26, 2010 1:34 pm

    wolverine wrote:All of the caps underneath the board are .22, this does not seem to be correct according to the parts list from Bob. Anyone?

    Thanks
    wolverine

    Hi,

    C5 through C8 are .22 uF @ 600 volts or higher.

    On C1 though C4 usually two are placed on the top (C1 and C2) and two are placed on the bottom (C3 and C4) of the board. These 4 caps are .10 uF caps @ 400 volts. Usually you wind up with then SIX caps placed on the bottom of the board. Four are the main coupling caps (C5 - C8) and they are .22 uF as you mentioned but the two other caps (C3 and C4) are .10 uF caps.

    Bob

    wolverine

    Posts : 60
    Join date : 2010-02-20

    Caps.....

    Post by wolverine on Fri Mar 26, 2010 1:41 pm

    The board I rec'd from Roy has all 8 caps on the bottom, and all are .22 Solen caps. So how does this effect my problem, and is this simply a mistake from one of Roy's assemblers Bob?

    Thanks again,
    wolverine

    It is possible that when the power supply blew on you it could have taken out some part on the driver board ??

    You CAN put all 8 capacitors on the bottom of the board if you want and (I believe ?) you CAN go up one size from .10 to .22 uF for C1 though C4. Whether this is the reason why you have issues with your amp - I can't really say. I will Email Roy and have him look at your post here ..

    Bob

    wolverine

    Posts : 60
    Join date : 2010-02-20

    My Board version.....

    Post by wolverine on Fri Mar 26, 2010 1:53 pm

    By the way, my board is exactly what your picture shows so I do have an older version. I can't remember when I bought it but Roy would know from my name I'm certain he keeps records. To the best of my recollection it has been about a year and a half. Since I lost that power supply I bought from Kevin and attributed it to the board I just shelved it finally thinking I would get with Roy later on and solve the problem.

    wolverine

    wolverine

    Posts : 60
    Join date : 2010-02-20

    Thanks yet again Bob.....and a twist here now....

    Post by wolverine on Fri Mar 26, 2010 7:34 pm

    wolverine wrote:The board I rec'd from Roy has all 8 caps on the bottom, and all are .22 Solen caps. So how does this effect my problem, and is this simply a mistake from one of Roy's assemblers Bob?

    Thanks again,
    wolverine

    It is possible that when the power supply blew on you it could have taken out some part on the driver board ??

    You CAN put all 8 capacitors on the bottom of the board if you want and (I believe ?) you CAN go up one size from .10 to .22 uF for C1 though C4. Whether this is the reason why you have issues with your amp - I can't really say. I will Email Roy and have him look at your post here ..

    Bob

    I replaced the .22 caps that should have been .10 using two Solens and two orange drops I had on hand, according to the board layout and the parts list that first made me notice the caps were not as spec'd. I biased the amp right to .40 at each tube with no problem and ran it for an hour using some small Sony surround speakers I typically use for testing. The speakers measure at 6.7ohms. It sounded great and was stable, though I was still only able to use the 8ohm tap, the 16ohm when used for NFB would instantly start oscillating. Remember I had that problem from day one before ever losing that power supply.

    I hooked up to my main system using a pair of Klipsch Heresey's which also measure in at 6.7ohms, and as soon as the bias started to climb I got that freakin oscillating again LOL. I did not change the 220ph over to 300ph yet, or the resistor values from 7.5 to 5.1. I'll need to order more parts.

    The bottom line is I cannot understand how this could continue to have the same problem in different amps that I have tried it in. It couldn't have been the loss of the power supply since it did the same thing before I ever had that occur. I need the knowledge of GP49 and a scope at this point I guess to really tune this in, but it is very baffling to me. Roy has had great success with his boards, yet I rec'd an assembled board with different caps then specified and the board has never worked right for me. Murphy's law here I think Bob LMAO.

    Thanks for your time old man, and that of Roy also for his continued help and support

    wolveine

    Sponsored content

    Re: VTA board and parts placement..... :}

    Post by Sponsored content Today at 10:57 pm


      Current date/time is Fri Dec 09, 2016 10:57 pm