Messiah 2, v5/v6 new clock diagram. [UPDATE BY CHARLIE]

[EnTiTy]

no problem m8 i dont think it will be a messiah 2 problem it dont sound as if he knows what hes doing let me know how you get on.
EnTiTy

[charlie_ps2]

The issue with the CLK needs explaining.

1. This is a 36MHz clock; above 20MHz, sensitivities arise
   
2. These sensitivities are dependent on the install environment
   
3. The CLK wire is its own capacitor and its length degrades the output. The shorter the wire, the lower the likelihood of degradation.
   
4. At 36MHz, inductance can also become a problem. This can then affect adjacent circuits.
   
5. The truest clock signal presents at the Messiah 2 if the CLK wire is close to a reference ground plane. Thus 'effects' can occur if the wire is bent high, and much less likely if laid along the motherboard.
   
6. The easiest way of providing a reference ground plane is to use a twisted pair of wires; one pole would be the CLK signal, the other wire would be grounded to the nearest ground point. This would stablilise the clock along the length of the CLK wire.

I hope this explanation helps everybody who might be affected.

To be frank, this is the penalty of not putting a resonator directly on the chip - but that requires more power and adds component cost.

[EnTiTy]

the twisted pair work's just fine for me charlie without any further problems or sound issue's.
EnTiTy

[Super_Chunk]

I have just one queston.. I'm about to install my new M2 on my NTSC V7..

This thread's name is v5/v6 new clo..... etc... so does this mean that the original M2 diagrams in Charlie's install pdf are correct for a V7?? should I use a twisted pair/coax cable??

Thanks

[charlie_ps2]

Originally posted by Super_Chunk
I have just one queston.. I'm about to install my new M2 on my NTSC V7..

This thread's name is v5/v6 new clo..... etc... so does this mean that the original M2 diagrams in Charlie's install pdf are correct for a V7?? should I use a twisted pair/coax cable??

Thanks

The phenomenon has not been reported on v7 (but looking at the science it's not impossible). So go by my item 5 in the foregoing advice I posted.

[EnTiTy]

ive installed the messiah 2 in about 25+ v7 and have not seen this problem at all most v5s i have done this problem occurs and the twisted pair works fine and corrects this issue but its not impossible for a v7 to suffer from this you can recreate the problem on a v7 by using a long wire for the clock signal so use a twisted pair or do the install as normal and keep the clock wire as short as possible.
EnTiTY

[fiv5]

with regards to my gnd comment, the diagrams have changed now, but i agree i made a mistake ( i took the point as being the solder pad next to where the laquer was removed - why go to the trouble of removing conformal coating when there are so many other easy gnd points available?) As i say the diagram has changed now anyway so no matter.

[EnTiTy]

its not a problem m8 i had to check twice to make sure it was correct and yes there are many easy ground points without the need to remove the enammel coating.
EnTiTy

[villasg]

Can i use for clk no a twisted pair but a cablle from sound card ( cable from cdrom to card) or cable from a wokman ( from head phones ) ???
That cables have shield and is very thin.

[charlie_ps2]

villasg - I sent you an e-mail in answer to your PM and forgot to add that no second diode would be required to be fitted by you.

To answer your question in this thread, shielded cable causes inductance which you don't want. My best advice is to do one of the following:

1. Use Techy's alternate CLK point if you have the v5/v6
   
2. Lay the CLK wire flat on the motherboard not crossing any components and use thicker wire
   
3. Use twisted pair with the other wire grounded on both ends.

Full explanation is given earlier in this thread.