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Typical Video Board issue with all Mac SE versions and SE/30.

In all my years I have never seen that part fail. But since its been over 20+ years, sooner or later it would have too fail. Nothing last forever.

 
I just repaired 3 video boards.

also this site also talks about this issue.

Repair Macintosh SE/30

http://www.biwa.ne.jp/~shamada/fullmac/repairEng.html

BrightScanLines.gif


(5) Troubles of the transistor Q1 on the video board. The video board is a small board where the CRT socket is soldered.
Click to expand...
(5) If none of the above doesnt't work, replace the transistor Q1 (2N3904, NPN transistor) on the video board.
Click to expand...
 
ok looks like its in DMS as well.

[SIZE=9pt]Symptoms: [/SIZE][SIZE=9pt]There is raster but no video display. The raster is very bright. Horizontal scan lines are visible.[/SIZE]


[SIZE=65pt]
BrightScanLines.gif
[/SIZE]
[SIZE=9pt]Probable diagnosis: [/SIZE][SIZE=9pt]The problem is on the CRT socket board [/SIZE]

[SIZE=9pt]Solution: [/SIZE][SIZE=9pt]Check/replace the 2N 3904 transistor (NPN, 0.6A, 1/2 watt, TO-92) at board reference Qi. Depending on the board revision Q1 could either be on the left or on the right. Also see the prior entry. [/SIZE]
Click to expand...
 
Hi all, I'm a new member of this forum... Some days ago a friend of mine gave me a SE/30 he had kept in his garage for years. It had the same video issue described in this thread and no sound. I did a total recap of the logic board (and checked every capacitor) and got the sound again but not the video issue. Then I tried to replace the 2N3904 transistor, but no luck again.
I checked the resistors on the logic board and they seem to work as expected.
Any other clues? What should I try?
se30video.JPG
macse30.JPG


macse30.jpg.dd561ea546db0a9fd021c1685ec393b4.jpg


 
in this case it looks like you have a botched UE8 on the mainboard.  — probably cap goo'd up.

At the least you can hot air flow it off, clean it up … and flow it back on.

 
LIttle more info:

from my post over on thinkclassic.org

https://www.thinkclassic.org/viewtopic.php?id=59

One of the biggest issues i have with the SE/30 is UE8,  there is a cap right there and it leaks its OOze right on/in UE8,  Sometimes the I/C goes bad because of this.   Sometimes you can hot air flow off UE8,  And flux&wick clean up the pads… get some fine grit sand paper and clean up the legs of UE8 and re attach it and it will work fine.

but sometimes you need a to replace it.

UE8 issues = No Video
UE8 issues = Video with lines (pin stripes)
UE8 issues = Can give you the same symptoms as a bad Video board ( on the back of the crt )

Here is the big one. and yes this has happen to me now 2 times.

UE8 issues = Depending on on what level of damage the cap goo has caused, And how the I/C has failed — can cause a No tone, No Boot!  Yup!

I was surprised my self, I found this one by accident...

^^ one other cause for Pinstripes in your SE/30 Video ^^

Datalines 0-7 come from the VRAM.
Sometimes the via's can rot (via's right near UE8) that are datalines  0-7 coming from the VRAM.
So in this instance you have to run a patch wire from the correct pin of UE8 to the vram.

You can check what one is bad with the se/30 schematics and and multimeter and check for 000 ohms 0-7
and if you get one with no continuity, that is the line.
Click to expand...
 
LS = Low speed/power shottkey. 

HC = High speed cmos. 

HC will work in place of an LS, but will be a bit more power hungry. 

 
just you can buy ether or.  people on this forum have bought the HC and it worked just fine.  Mike just buys the LC version from Digi-key and it works out just fine as well.  if it was me i would buy 10 at a time,  and i guess i would choose what ever version was the best deal :) they look like they are about 80 cents each.

Package / Case: SOIC-16 Logic Family: HC Logic Type: CMOS Number of Input Lines: 9 Propagation Delay Time: 150 ns, 30 ns, 26 ns Maximum Operating Temperature: + 85 C Minimum Operating Temperature: - 40 C Packaging: Reel Function: Shift Register   Mounting Style: SMD/SMT        
 
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