R450 - Unexpected Connection Between Board Under Test and System Ground Ground, Connection, Board, Test, Between

wang00570657

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Guanjie.wang@pemstar.com

tony0716

没问题!
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tony0716

Revision: B.02.xx

The "R450: Unexpected connection between board under test and system ground" is generated during the "unpowered" command in the testplan. All unpowered test techniques on the Agilent 3070 require that the board under test not be connected to system ground, so the connection must be removed before unpowered testing can proceed.

This error message can occur on fixtures that have worked without problem, it can be intermittant, and it can occur on testheads that pass full diagnostics. The connection that the system is detecting can usually be located by checking the following items:

Check for external instruments connected to the tester, including ground leads. If you have a testing need for external instruments to be connected to your board under test, the best option would be to utilize an AccessPlus card. The AccessPlus card has special connectors that attach to the external instruments. When a powered test requires the external instrument, relays on the AccessPlus card are closed connecting the instrument to the board under test. This enables you to use external instruments when required without affecting any of your unpowered tests. If you cannot use an Access Plus card for your external instruments, and your software is at B.02.54 or greater, please contact your Agilent Support Representative for an alternate solution.
Check any testjet hardware that you may have on your fixture. Sensor plates touching the board, testjet mounting screws touching the fixture, and testjet mux cards shorting to tooling pins have been known to cause this error.
Check for fixture wires or testhead mint pins that may be shorting to the metal frame of your fixture.
Check for bent personality pins in your fixture that may be going through the same hole in the alignment plate of your fixture.
If you are using an XG-50 fixture (fixture that contains a ground plane), check that the ground plane is not touching the fixture anywhere.
If you are using the ConnectCheck software, check that your wiring to the Testjet Mux + Ref card is to connector J6 (NOT to connector J1).
Check for miswiring between ground (also referred to as "unswitched" ground) and "switched" ground on the control card. (NOTE: Switched grounds tie the system ground to the board under test's ground with the execution of the "powered" statement. Normally, switched grounds are used for all ground connections to a board under test. Unswitched grounds are always tied the the 3070's ground. Unswitched grounds should never be tied to a board under test node.) To verify your ground BRC wiring, refer to the Agilent 3070 Series II Users' Manual: Cards In The Testhead.
If all of the above fail, check the system hardware by running full diagnostics.

tony0716

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