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Aug 23rd, 2008 at 11:18pm
Are the modem RX F connector socket internal capture springs good ? Check by gently inserting a test length of centre pin wire. The internal springs may be burned, corroded or physically damaged. The diameter of F connector centre pin wire is not a specified standard and if larger diameter wire has been used before a new narrower wire may fail to make contact due to spring stretch. Does a DC voltage appear at the modem RX F socket ?
Was the F plug put in properly ? Is the centre pin marginally short ? It should stick out proud of the plug rim by about 1.5mm. Is the braid reliably connected ?
Did the LNB change temperature and thus LO frequency change also when the modems were swapped ? Does widening the frequency search range help ?
18V and 10 MHz were mentioned above. Why ? Are the options files the same or different in these respects ? If the LNB 10 MHz reference is on, why ? Very few LNBs need external 10 MHz reference. It is possible for PLL LNBs with external references to have intermittent synth lock fault. Cycle the power several times and try waggling cables and knocking the LNB to see if you can make it fail/work. Some LNBs will change LO frequency with 13/19 volts.
As Mike says, the receiver/demod may be faulty.
Best regards, Eric
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