Hi Tommy,

> I spotted following chips:
> cd40106b
> cd4006
> cd4070
>
> Please let me know what the others 2 are and if these are correct.

There are *two* 40106, and the 8-pin chip is a dual op amp (TLC272 in mine).

> It sounds to me as if there is an oscillator that drives the digital sound source and only the driver is functioning.

Correct. The 40106 at the bottom of the board acts as 6 oscillators for the '808 source'; the other one (topmost on the board, opposite the pot), is the tunable oscillator that clocks the 4006 shift register, which is what generates the digital noise.

If it is running OK from the ext clock, then it sounds like that top 40106 might be blown - you could easily swap it with the other to see what happens (indeed, checking that all the ICs are firmly pressed into their sockets would be a good thing to do).

> In this picture:
> http://3.bp.blogspot.com/_d9uh_FFQZoQ/SW_321zu3zI/AAAAAAAAAFM/vAu-C9ki aw4/s1600-h/a117m.jpg
>
> If I make this simple connection the unit sounds good when something is patched into the ext. Clk input AND can be tuned.

Sorry, I don't quite follow that - is that both ends of the same wire If so, it is hard-wiring the internal osc to the 4006 clock input (i.e. just bypassing the switching contact in the jack socket), in which case the comment about it working when something external is connected doesn't make sense to me, nor it being 'tuned' !

Tim