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SE/30 Chime but black screen

Posted by: bibilit on 2016-09-18 07:55:12 I have a SE/30 with the above issues. In the first place i had no video and faint sound, replaced caps on the logic board, now have very loud chime but still no video. Replaced UE8 also, still same issue. The Analog side is ok, tested with a good logic board. Screen is all black. Any idea ?

Posted by: CelGen on 2016-09-18 09:17:09 Have you verified the tube has even got a lit heater?

Posted by: BadGoldEagle on 2016-09-18 10:24:58 I don't think the tube's the problem. I happen to have the exact same symptoms with one of my SE/30 boards. UE8 has been replaced too.  I sent it to techknight's with the Portable Logic board a couple of months ago. Maybe he can help?

Posted by: bibilit on 2016-09-18 10:27:55 The tube is OK, tested with another board. i have tested a couple of things, the obvious ones (Ram and Rom, Video Rom) a bit lost right now.

Posted by: Elfen on 2016-09-18 12:19:33 Have you checked the plug in jack on the logic board? True this section fails in the Analog Board a lot, but it also fails in the logic board too. Just desolder, clean up and resolder the connection.

Posted by: bibilit on 2016-09-19 02:54:41 Can have a look, but not confident. thinking about Vram in the first place.

Posted by: techknight on 2016-09-19 05:53:48 I had this happen twice. One time it was PALs, and another time it was the output pin trace from UE8 broke.

Posted by: Ferrix97 on 2016-09-19 06:08:30 I had two boards with the same issue (one with no video at all, the other with partial video), replacing UF8 and UG8 solved my problem. Actually, the no-video one wasn't even able to boot and could not be tested with a TechStep. https://68kmla.org/forums/index.php?/topic/22545-macintosh-se30-killed-by-a-mouse/?p=302607

Posted by: bibilit on 2016-09-19 07:46:27 Hi, Great, thanks, i did see your post but was focused on the partial video one, didn't realised there one one with a black screen as well.

Posted by: Ferrix97 on 2016-09-19 07:56:34 Yeah, I bought a second board for replacing the first one but it turned out that the second board had more problems than the first one

Posted by: bibilit on 2016-09-24 02:37:15 thanks to all of you. Yesterday spent all the evening looking for broken traces, all was ok. Following the advise of Ferrix i removed and replaced both UF8 and UG8, the screen lit up  🙂  but scan lines were present, just like my last one: https://68kmla.org/forums/index.php?/topic/28003-mac-se30-screen-too-bright-with-scan-lines/ so removed again UE8, cleaned all pads again and soldered back. In the end, i think all of them were bad. once all was put back together : Still have a small problem with floppy drive, but no big deal.

Posted by: Ferrix97 on 2016-09-24 03:14:23 Great! It looks like those video issues are getting more and more common, probably because those ICs don't like capacitor goo around them. Out of the three boards I have, two of them had the same issue as yours, and the third one had a broken Data line on the SCSI IC.

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