NotTaR of Television Sets : Troubleshooting a TV with the mainboard ..  
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Troubleshooting a TV with the mainboard disconnected

There are times when it is desirable to remove the chassis or mainboard and work on it in a convenient location without having to worry about the equipment which will simulate the critical functions but this is rarely an option for the doit-yourselfer.

My approach is usually to do as much work as possible without removing the main board and not attempt to power it up when disconnected since there are too many unknowns. Professionals will plug the chassis into a piece of equipment which will simulate the critical functions.

Note that if you have a failure of the power supply - blown fuse, startup, etc., then it should be fine to disconnect the CRT since these problems are usually totally unrelated. Tests should be valid.

However, if you really want to do live testing with the main board removed, here are some considerations. There are usually several connections to the CRT and cabinet:

If you do disconnect everything, make sure to label any connectors whose location or orientation may be ambiguous. Most of the time, these will only fit one way but not always.

These include both controls accessible to the user (and often not understood) as well as internal adjustments that may need to be touched up due to the aging of components or following a repair.

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