ldg@yoda.byu.edu (06/05/90)
Our venerable Mac Plus has lost its video. All that is left is a faint
vertical line up the center of the screen. When my Mac 128k needed a new
"analog board" I seem to remember the same thing happening. In both cases
the final failure was preceded by intermittent flashes on the screen.
I have a few sources for flyback transformers, but it would be nice to know
if I have correctly identified the problem before I buy the part.
Lyle D. Gunderson N6KSZ | "Any technology without | ldg@yoda.byu.edu
350 CB/BYU | some attendant risk of misuse | CIS: 73760,2354
Provo UT 84602 | is probably trivial" | GEnie: L.GUNDERSON
| --Louise Kohl | AO: LGundersongordon@milton.acs.washington.edu (Gordon Davisson) (06/07/90)
In article <173ldg@yoda.byu.edu> ldg@yoda.byu.edu (Lyle D. Gunderson) writes: >Our venerable Mac Plus has lost its video. All that is left is a faint >vertical line up the center of the screen. When my Mac 128k needed a new >"analog board" I seem to remember the same thing happening. In both cases >the final failure was preceded by intermittent flashes on the screen. > >I have a few sources for flyback transformers, but it would be nice to know >if I have correctly identified the problem before I buy the part. It's a little hard to tell from the description (it's a thin line, like a millimeter or less thick, right?), but it sounds like what happens when one of the solder joints on the yoke connector (the 4-pin connector near the top front of the analog board) cracks. It's almost always the top pin that goes, but theoretically the second from the top could also cause this. Other possibilities include bad connections on C1, L2, L3, or the flyback, or failure of any of these components. Try resoldering these before you invest in any replacement parts. -- Gordon Davisson Westwind Computing (206) 632-8141 4518 University Way NE, Suite 313, Seattle WA 98105
etxtorn@juno11.ericsson.se (Thomas Tornblom Konsult TM/JU 99367) (06/07/90)
In article <173ldg@yoda.byu.edu> ldg@yoda.byu.edu (Lyle D. Gunderson) writes: >Our venerable Mac Plus has lost its video. All that is left is a faint >vertical line up the center of the screen. When my Mac 128k needed a new >"analog board" I seem to remember the same thing happening. In both cases >the final failure was preceded by intermittent flashes on the screen. > >I have a few sources for flyback transformers, but it would be nice to know >if I have correctly identified the problem before I buy the part. > >Lyle D. Gunderson N6KSZ | "Any technology without | ldg@yoda.byu.edu >350 CB/BYU | some attendant risk of misuse | CIS: 73760,2354 >Provo UT 84602 | is probably trivial" | GEnie: L.GUNDERSON > | --Louise Kohl | AO: LGunderson 1:st check and resolder all solder joints on the fly back x-former and cable connectors. Seems this is a very common problem with the plus, my mac died the same way. My 10 years old stereo amplifier died the same way and I thought the switches was bad so I phoned the manufacturer and checked if I could get new ones. A guy there said that the problem was not that the switches was worn out but that the pins on the switches was made of brass. If you use the wrong kind of solder on brass the zinc will eventually "float" out into the joint and make up a bad connection. You can see it as a very fine line in the solder around the pin. So I sucked the old solder away and did the joints with fresh solder and both my old amp and my mac works as they did when they were new. The amp manufacturer now uses switches with pins of bronze.