Vintage DD turntables. Are we living dangerously?

Dear JP, Congratulations on your perseverance and genius in pursuing the Mk3 "problem" to its potential solution.  Now that you're here, and pursuant to Dover's lament and criticisms, did you mean to infer that the apparently increased accuracy of your circuit vs that of the MN6042 would confer a meaningful, not to say audible, improvement in the performance of the Mk3?  That would be really something to behold.  Like I may have said above, in reading your posts on Audiokarma, I was not sure that the few Hz by which your circuit "beats" the MN6042 in accuracy would necessarily translate to performance.  But this is also because I may have a misconception about the true meaning of those data points you posted.  Can you comment further?

Also, I will be contacting you privately about purchasing one of your boards.  Thanks again for your work.

Dear Dover,  To ask a question or to wonder is not to "trivialize".  The basis for learning is questions and answers. That's about all I can say to you that is not vitriolic.  I would hope that JP appreciates the fact that my earlier post meant him no disrespect at all.  In fact, I am rather amazed at his work, since failure of the MN6042 has been the downfall of many Mk3s.

Dear JP, I now see that you did in fact respond to my question about the accuracy of your circuit vs that of the MN6042.  Sometimes these threads move too rapidly for me to be current. I did wonder whether 262.XXX kHz was the operative number or whether it was the much higher frequency that gets divided to yield 262.XXX kHz.  Now I know it is the latter, which enhances the significance of the difference between your circuit and that of the MN6042.  What's additionally appealing about your circuit is the fact that if it ever should fail, it's fixable with parts that are readily available.

I still have question about the other chips inside the MK3. Are they easily found, not as important or just don't ever die?

rower 01-22-2016 1:19pm
I still have question about the other chips inside the MK3. Are they easily found, not as important or just don't ever die?

Someone like Bill T would have better first-hand knowledge, but in my research nearly all the examples I could find that had DN860 or AN660 failures had tell-tale signs of prior work that didn't appear very impressive.  I just didn't see any evidence of "spontaneous" failures for any of the other ICs like you do for the MN6042. 

The motor drive IC, AN640G, is still plentiful, but those don't seem to ever fail.  AN660s and DN860s still show on eBay once in a great while as have a couple MN6042 recently, but they're becoming few and far between unless you strip a lower model 'table. 

Not as easy as the MN6042, but I think something could be fairly easily made to replace the DN860.  That's not to say I think it'd be worthwhile though.  I've a bit over two months and well north of $1000 in to the MN6042 replacement.