most likely the neon bulb is being used to protect the picture from arcing, it's probably between ground and one of the tube electrodes that's normally no where near the 60-70 volts it takes to turn on a neon, but when there's a certain type of fault the lamp conducts and limits the voltage to a low enough value to prevent arcing inside the tube, which can do real damage to the tube. i've seen neons used for this on a number of monitors. the newer monitors usually just use a precision spark gap now, and often have one on several leads of the picture tube. so if the neon comes on, something is wrong, and it's preventing more severe damage.
i wouldn't keep flexing that board, you're likely to make more cracks and break solder joints, and possibly even break components. best to check all the traces with a magnifier and an ohm meter and solder a short wire across any break. if there are several breaks in a trace you might just replace the trace with a wire from one end to the other, in which case you want to glue it down, hot melt glue works well for this. in any case, DON'T use super glue, if any one ever solders on it and heats the super glue it will release a cyanide gas, which is amazingly nasty, i found this out the hard way and still felt tired the next day from just one quick whiff of very little of it. ------- > >While in the realm of Larry Pina type things (can't think of an > >analog board repair without thinking of L.P.) what is the little neon > >bulb (think it's a neon bulb) for on the Mac Plus analog board? I've > >got one board that probably has a bad solder joint of cracked trace. > >It's intermittent as far as working and when one flexes it a bit it > >cuts out (machine restarts or shuts down) and the neon bulb comes on. > >I figure that bulb must be a clue to what's happening when I flex the > >board. -------- -- "To preserve liberty, it is essential that the whole body of the people always possess arms, and be taught alike, especially when young, how to use them." (Richard Henry Lee, Virginia delegate to the Continental Congress, initiator of the Declaration of Independence, and member of the first Senate, which passed the Bill of Rights.) -- Compact Macs is sponsored by <http://lowendmac.com/>. Support Low End Mac <http://lowendmac.com/lists/support.html> Compact Macs list info: <http://lowendmac.com/lists/compact.shtml> The FAQ: <http://macfaq.org/> --> AOL users, remove "mailto:"; Send list messages to: <mailto:[EMAIL PROTECTED]> To unsubscribe, email: <mailto:[EMAIL PROTECTED]> For digest mode, email: <mailto:[EMAIL PROTECTED]> Subscription questions: <mailto:[EMAIL PROTECTED]> Archive:<http://www.mail-archive.com/compact.macs%40mail.maclaunch.com/> Using a Mac? Free email & more at Applelinks! http://www.applelinks.com
