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    Resistor Working Voltage

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    turbodan

    Posts : 5
    Join date : 2012-07-06

    Resistor Working Voltage

    Post by turbodan on Fri Jul 06, 2012 3:39 pm

    Hi All,
    I just purchased a bunch of Dale metal film resistors for a new PAS-3X build I am doing (PC5 and PC6 Boards). I see they have a maximum working voltage of 250V, and was wondering if they would see anything like this in operation. I assume the 100K plate loads would be the most probable location for a high voltage across the resistor, but just want to make sure. Should I go ahead and use them, or try to find some higher rated parts? Let me know what you think.

    Thanks!

    hawaii.ken

    Posts : 157
    Join date : 2012-01-31

    Re: Resistor Working Voltage

    Post by hawaii.ken on Fri Jul 06, 2012 4:19 pm

    May I ask what boards/mods are you using? Pictures would be great also!

    Original design voltage for PC-5 is 210v and 330v for PC-6 so your Dale metal film resistors should be OK.

    turbodan

    Posts : 5
    Join date : 2012-07-06

    Re: Resistor Working Voltage

    Post by turbodan on Fri Jul 06, 2012 5:31 pm

    hawaii.ken wrote:May I ask what boards/mods are you using? Pictures would be great also!

    Original design voltage for PC-5 is 210v and 330v for PC-6 so your Dale metal film resistors should be OK.

    Hi Ken,
    I have been lucky enough to get a brand new unassembled kit from a friend, the only problem is the PC5 board is missing. Everything is still in the original packaging, even the pots are in their Centralab cardboard wrapper. I don't have any pics of it yet, but I will be sure to take some as this seems like a somewhat rare find to me.

    I am curious to hear what the original sound was like, so I purchased a reproduction PC5 board and used the layout thread on this forum to decide what values to buy. That being said however, I am a big believer in beefing up the power supply, so I did purchase a PAS Regulator Board from Classic Valve Design. The only other modification I plan on making is implementing the RIAA correction on the PC6 board, so I can wire the selector switch for more line level inputs, as I have many devices that are line level.

    -Dan-

    hawaii.ken

    Posts : 157
    Join date : 2012-01-31

    Re: Resistor Working Voltage

    Post by hawaii.ken on Fri Jul 06, 2012 8:27 pm

    Hi Dan
    Note that I have mixed up the two boards in my previous post. Original design voltage for PC-6 is 210v and for PC-5 its 330v.

    Did your unassembled kit come with the original Dynaco labeled Telefunken tubes?

    I am still in the middle of modding my PAS-2 with boards (PAS-K and regulator) from Classic Valve Design. Before I started my mods I spent almost a month rolling tubes thru the PAS-2 with the original boards and build. The Telefunken tubes won hands down.

    turbodan

    Posts : 5
    Join date : 2012-07-06

    Re: Resistor Working Voltage

    Post by turbodan on Fri Jul 06, 2012 9:23 pm

    hawaii.ken wrote:Hi Dan
    Note that I have mixed up the two boards in my previous post. Original design voltage for PC-6 is 210v and for PC-5 its 330v.

    Did your unassembled kit come with the original Dynaco labeled Telefunken tubes?

    I am still in the middle of modding my PAS-2 with boards (PAS-K and regulator) from Classic Valve Design. Before I started my mods I spent almost a month rolling tubes thru the PAS-2 with the original boards and build. The Telefunken tubes won hands down.

    Yes, though they are labeled Telefunken and no mention of Dynaco. The 12X4 is labeled with Dynaco. From what I gather this kit was very late production, the PC6 I have is fiberglass board style, so maybe that has something to do with it.

    turbodan

    Posts : 5
    Join date : 2012-07-06

    Re: Resistor Working Voltage

    Post by turbodan on Thu Nov 01, 2012 10:08 pm

    Finally, here are some pictures:

    The tube boxes


    The tubes themselves (all are the same)


    More on the build to come soon...

    -Dan

    tubes4hifi
    Admin

    Posts : 1261
    Join date : 2008-11-30

    Re: Resistor Working Voltage

    Post by tubes4hifi on Sat Nov 03, 2012 8:04 pm

    no resistor in a PAS3 has more than 160v across it. Most 1/2 watt resistors are rated at 350v, and 1/4 watt resistors are rated at 250v.
    The 100K plate resistors on the PC5 board should be rated at 1 watt, as it actually dissapates .17w, a little high for a 1/2 watt if you want it to last several years.

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