On Tue, 8 Jan 2002, Adrian Graham wrote:
> Having read all the threads relating to board washing I've got a question.
> What are the panel's thoughts on video boards? I'm thinking of flyback
> transformers and the like......got a PET 8032SK here that I'm picking up on
> fixing again after a couple of months layoff - it's taken up smoking......
>
> Anyway; it's been turned off since early november time, and since the board
> has a thick layer of greasy grime all over it I want to give it a wash since
> I can't see where the smoke's coming from apart from 'close to the front at
> the right'.....
>
> Any help appreciated
If the flyback is sealed, it shouldn't be a problem. Most modern flybacks
are not 100% sealed, and have a couple of variable resistors on one side.
Typically, the flyback is installed after washing when these boards are
manufactured. You will often find flux on the pins for these types of
parts, since the board will have already been defluxed before the washing.
I'm not sure I'd wash such a board with the flyback installed, since they
are usually easy to remove, and often their solder joints need to be
redone anyway. Often when the flybacks are installed at the factory, the
joint is not allowed enough time to heat properly, so the solder does not
bond properly to the pin or pad. Over time, these solder joints are prone
to failures, which cause lots of intermittent problems in monitors and
TVs. Flybacks are also very expensive to replace, and it's often difficult
or impossible to find an exact replacement.
Make sure you properly discharge the CRT and other caps in the HV section
before disconnecting the anode lead from the CRT. You can find some basic
service and safety information on the sci.electronics.repair FAQ located
here:
http://www.repairfaq.org/
-Toth
Received on Tue Jan 08 2002 - 06:22:30 GMT