828MK3 link two sets 8pre with ADAT trouble - Help!!

[RYO]

I have two 8pre and one 828mk3, I tried to connect them by optical cable. connect the four optical cable with a noise is heard intermittently.

I listed the step what I have to do.
1. connect (A)8pre optical in port to 828 optical A out port.
2. connect (A)8pre optical out port to 828 optical A in port.
3. connect (B)8pre optical in port to 828 optical B out port.
4. connect (B)8pre optical out port to 828 optical B in port.
5. 828 firewire connect to PC.
6. Set the clock to "Internal".

I disable either ADAT A or B. The noise sound will disappear.
If I turn on both ADAT A and B, The noise sound will be back.

Please give some instructions to solve this issue. Thank you very much.

[4stripes]

FYI, when you clock digital devices together, they cannot all be set to internal.

You can only have one master clock. Everything else needs to be slave "external" clock. You need to clock your 8pre's via ADAT.

[RYO]

Thank You 4stripes, I switched each mode for the clock.
But the sound always like a loop...through each channel on ADAT B.
It is possible my 828 damage?

[mysticalcracker]

I'm having a similar problem. I'm starting to see a pattern. Has anybody been able to expand an extra 16 channels with mk3's?