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8751A Service Manual, Adjustment routine info or assistance appreciated

Question asked by goingplaces on Jan 8, 2014
Hello.

I have an 8751A that is failing the B receiver functional test (#35).  It's passing the R and A functional tests with no issues and when the B channel routine is run the issue is fairly obvious.  The unit measures the ref output at 10 MHz normally (marker reading ~1 dBm) but then when the CF is switched to 9.99 MHz instead of the delta marker being way down in the noise floor it's measuring right around -30 dB.

A manual check using the same settings as the internal routine provided the same results.  Other than that however, there are no outward signs of a failure.  The B receiver tracks very similarly to the A receiver and looks to have good dynamic mag accuracy (though I just did a cursory check not the performance test).

Can anyone provide some input as to where the service manual can be found, how and what adjustment routines might be run to correct the issue or input as to whether the unit has a hard failure that likely won't be corrected by an internal adjustment?

Thanks.  

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