Fixing RGB Output

[Dal]

My ACE stopped generating video (No VSYNC) last week.  Looking at the Wiki, there is this article which seems to describe my situation:
http://www.gamesx.com/wiki/doku.php?id=x68000:fixing_rgb_output

The article suggests replacing the 74ALS05N.  However, the picture shows this as being north of the video bus connector next to the bank of ZIP chips (IC8).  When I look at my board, this location has a 74LS244 in there. The 74ALS05N is actually south of the video bus connector (IC6).

So, now I don't know whether the IC location or the chip type is incorrect in the article.  Do I replace the 74ALS05N or the LS244N?

[eidis]

 Hi Dal !

As the article says, the 74ALS05N sync inverter is the culprit. Check if RGB output pins 14 and 15 go to this chip, to be completely sure.

74LS05 - Hex Inverter (Open Collector)
74LS244 - Octal Driver Tri-State

Keep the scene alive !
Eidis

[Dal]

Thanks. I replaced the ALS05N but my problem persists. More investigation required in my case.

[costa]

This NO VSYNC message is not misleading you?
Maybe it is not just bad capacitors on the video module?

My X68030 came without video signal, I replaced the caps in the video module and it fixed the issue.

Thanks. I replaced the ALS05N but my problem persists. More investigation required in my case.

[Dal]

That's a good point.  There are quite a few in there too so quite likely.  Definitely no harm in replacing them. 

[gypsie]

Hi,

My X68k compact have a black screen on startup (no picture of the "insert disk..." ).

I will change all the capacitors next week...

[costa]

Good luck, man.
Very careful with the small bastards next to the ADPCM... there are some wires around them than makes thethe removal and soldering of  new ones back a real challenge.

Hi,

My X68k compact have a black screen on startup (no picture of the "insert disk..." ).

I will change all the capacitors next week...

[gypsie]

All caps changed and the mobo is working fine!!!!!

Only the 2 floppy drives don't  work

[Dal]

I still have mine to do. Im going to try the caps on the video riser board first. Machine has been put away for now though. Probably look at it in the next month or so.

[eidis]

 Hi Gypsie !

Try testing the FFC cables, which connect floppy drives with motherboard, for continuity. There could be a broken trace or intermittent signal. You might also want to try replacing them. I think they are 34 pin FFC with 1.25mm pitch. The closest and cheapest which I could find were these:

1pcs FFC FPC 40-pin 1.25mm Pitch Ribbon Flat Cable Wire ZIF HDD 300mm Long New
http://www.ebay.com/itm/1pcs-FFC-FPC-40-pin-1-25mm-Pitch-Ribbon-Flat-Cable-Wire-ZIF-HDD-300mm-Long-New-/151333074075?pt=LH_DefaultDomain_0&hash=item233c27749b

Just cut off the unneeded pins with X-acto knife and you're good to go. Recaping the floppy drives could be a good idea too.

Keep the scene alive !
Eidis