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


    Dirty, waxy, gummy Dynaco PCBs

    Share

    j beede

    Posts : 316
    Join date : 2011-02-07
    Location : California

    Dirty, waxy, gummy Dynaco PCBs

    Post by j beede on Sat Jun 18, 2016 6:42 pm

    I have never found a really effective way to clean old Dynaco PCBs. I am not sure what the waxy, gooey stuff that the boards are covered with is--but I know I'd like to get it off. Anyone have a favorite recipe to share?

    MontanaWay

    Posts : 767
    Join date : 2014-02-06
    Age : 58
    Location : Cameron, Montana

    Re: Dirty, waxy, gummy Dynaco PCBs

    Post by MontanaWay on Sat Jun 18, 2016 8:38 pm

    j beede wrote:I have never found a really effective way to clean old Dynaco PCBs. I am not sure what the waxy, gooey stuff that the boards are covered with is--but I know I'd like to get it off. Anyone have a favorite recipe to share?

    easy! buy our clone PC5 and PC6 PAS upgrade kits! Wink

    PeterCapo

    Posts : 380
    Join date : 2008-12-05

    Re: Dirty, waxy, gummy Dynaco PCBs

    Post by PeterCapo on Sat Jun 18, 2016 11:34 pm

    j beede wrote:I have never found a really effective way to clean old Dynaco PCBs. I am not sure what the waxy, gooey stuff that the boards are covered with is--but I know I'd like to get it off. Anyone have a favorite recipe to share?

    The bottom side, a.k.a. "foil" side, of the original, brown Dynaco PCBs were purposely coated with wax. It's likely beeswax or some blend of waxes that protects the phenolic substrate from moisture.

    Don’t remove it!

    PeterCapo

    Posts : 380
    Join date : 2008-12-05

    Re: Dirty, waxy, gummy Dynaco PCBs

    Post by PeterCapo on Sat Jun 18, 2016 11:56 pm

    If you were to "clean" the wax off, the phenolic substrate would destabilize in some way (I found out the hard way a long time ago).  The board will no longer be protected from moisture, which could cause it to warp and otherwise physically degrade over time.  I cleaned mine with a lot of 91% isopropyl, and the boards warped and became very brittle - barely usable.

    I discussed this issue with some chemical companies that make solvents and conformal coatings for PCBs, as I considered trying to find a better way to dissolve or even melt the wax off and then reapply some kind of fresh conformal coating to continue protecting the phenolic substrate.  Unfortunately, one place recommended against using certain modern conformal coatings with phenolics, and even present-day coatings don’t necessarily protect from moisture as well as wax does.  Another place I spoke with was concerned that any chemical used to remove the wax could take up residence in the substrate and physically destabilize it.

    Who knows what else could happen over time.  Anything that could dissolve the waxy gunk might also contribute to the pads and etches delaminating, which are not well-bonded to the substrate in the first place.  Might also reduce the electrical resistance of the substrate between etches.

    The phenolic material is just not very robust.  But, this should certainly not be taken as evidence that the original Dynacos were cheaply made.  The PCB technology just wasn’t up to where it is today.  By the 1970s, Dynaco had begun using the newer green epoxy PCBs.  

    If you want to keep them, my suggestion would be to do as little as possible to original, brown Dynaco PCB substrate.  The dust and built-up grime on the top side can be wiped or brushed off, but on the bottom side leave the wax alone.  They'll remain gunky-looking underneath, but they can still work perfectly fine even if new parts are installed.  If the pads or etches delaminate from desoldering/soldering heat, you can just run the part’s lead a little further along the etch to make the needed connection.

    Sponsored content

    Re: Dirty, waxy, gummy Dynaco PCBs

    Post by Sponsored content Today at 11:36 am


      Current date/time is Sun Sep 25, 2016 11:36 am