[DSP-10] PLL Problems

[Tan Teik Chuan]

I performed the PLL diagnostics and got the following readings:

U104-3: 5V
U104-4: 5V
U7-16: 4.7V
Across R44: 0.12V
U105-1 In: 0.9V
U106-1 In: 1.3V
U8-1 In: 1.3V
U9-1 In: 2.2V
U104-7: 2.2V (means it is not locked?)
U7-11: 4.7V (means it is locked?)

U107 and U108 were programmed correctly.

For 124-128Mhz PLL, U104-5 gave voltage about 4.7V. I've tried to 
temporarily connect a ground to the junction of R105/C113, remove the core 
from L102, and even change the number of turns to 15 turns. But, it is still 
unlocked. I haven't try to change the C117 to 6.8pF because I do not have 
one. I measured frequency using a scope at "126Mhz LO". It showed about 
127Mhz.

Since U7-11 gave 4.7V and the frequency at "19.68Mhz LO" was about 19.7Mhz. 
Can I assume 19.68Mhz PLL is locked?

Regards,
Tan Teik Chuan

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