68kMLA Classic Interface

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5 boards to have a crack at
Posted by: falen5 on 2015-04-11 19:46:10 what are the PALS....the ux8 chips?.............jasus ...im sure you told me before!!!!!
Posted by: techknight on 2015-04-11 19:47:16 All the socketed chips nearby. Out of all the SE/30 boards I had rebuilt, I have seen ONE case where the PAL/GALs were bad. it was causing the analog board to scream bloody murder. Replaced em, came back to life.
Posted by: falen5 on 2015-04-11 19:49:15 jesus - great bleedn idea thechknight - will have a look - cheers man
Posted by: falen5 on 2015-04-11 19:59:57 heres what I did tonight - took off UE8 and UC8 ( to find the via for one of the pins) - this exposed all the first via's , along the trace , to all the missing pads left - got smaller wire - finished it up ( no picture, time!) - but its still the same - will put up more pics tomorow
Posted by: falen5 on 2015-04-12 07:56:35 Techknight - went to swap out the PALS only to find they are all soldered into the board. Swapped out the video rom - still no joy. - heres where it is at now. - Id better get this going soon because the more I go at it the weaker all the connections, pads, traces are getting. - I have metered out the UE8 with my good board and it checks out...cleaned the boards both sides........I just cant find the fault...........it has to be something stupid.
Posted by: falen5 on 2015-04-12 10:03:15 somebody gave this description in another post of same problem "the Vertical Sweep IC at U2 (TDA1170A, 12-pin)" - what chip is that?..........I cant see a 12 pin chip on the se/30 board anywhere!............is this chip on the analog board? - I have metered out all the Ux8 chips and compared them to a good board. EVERY PIN IS CORRECT - is there anything else that's would cause the horizontal line. - would it be worth metering out all the pals
Posted by: 360alaska on 2015-04-12 10:16:01 Isn't that U2 on The analog board?
Posted by: falen5 on 2015-04-12 10:19:37 thanks 360alaska. - the analog board is good. When I swap in my good board display is perfect..............so its this darn motherboard. - I just cant find the problem and I cant hot air gun chips off anymore, the pads will all come off if I keep swapping chips - have to go on the assumption the chips are good - ah well..........off to a gig..........will spend hours staring at this thing later
Posted by: falen5 on 2015-04-12 10:21:12 yep - you are right - I just read the rest of the post where I heard about the U2 and indeed he was referring to the analog board - my bad - its desperation at this stage - weh hey!
Posted by: techknight on 2015-04-12 10:29:09 Well you need to look at the schematic. where is the vertical signal generated? the PALs I believe. Even though they are soldered on, I would replace the one that is directly responsible for generating the vertical sweep drive. Messing with UD8/UC8, etc all day isnt going to fix this problem I dont believe.
Posted by: 360alaska on 2015-04-12 10:33:54 yep - you are right - I just read the rest of the post where I heard about the U2 and indeed he was referring to the analog board - my bad - its desperation at this stage - weh hey! Alot of those suggestions come from here: http://www.biwa.ne.jp/~shamada/fullmac/repairEng.html But of course, you know you analog board is good... Unless that board has a short somewhere that damaged U2, Unlikely though...
Posted by: falen5 on 2015-04-12 15:00:15 thanks for all you help people. - looks like I will have to do a crash course on reading schematics and on how to use them. - until I do I am probally wasteing peoples time. - anybody got any links to any good tutorials on utube
Posted by: uniserver on 2015-04-12 15:55:33 http://museum.dyne.org/gallery/apple/stuff/mac/andreas.kann/schemat.html maybe this graphic i made will help you?
Posted by: falen5 on 2015-04-12 17:09:06 thanks uni - I looked at the drawing and understood nothing............then again im drunk as a lord - weh hey! - to be honest ive got to the stage where I must understand what is actually going on , on the board - what ALL the chips do etc etc - this is becoming an obsession.......just have to understand the board logic, use it to understand a problem, and again use it to find and fix the bas%$£d of a problem - It kills me not having the knowledge I need to understand this - off to utube for tutorials............god help me - thanks again all
Posted by: falen5 on 2015-04-12 17:48:37 techknight - totally agree with you there
Posted by: falen5 on 2015-04-15 18:24:45 Update....... - Success ........... -
Posted by: techknight on 2015-04-15 19:00:52 blank video.
Posted by: falen5 on 2015-04-15 19:18:12 try again techknight...... its processing 1,3 gig of dv fottage..........will work when done
Posted by: uniserver on 2015-04-15 20:30:49 good job!!! u is the man!
Posted by: bigmessowires on 2015-04-15 21:55:07 It looks like now the SWIM chip has problems, or the floppy drive is bad? It keeps flashing an X on the disk icon on the boot screen.
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