Last post by Ex68Kay - October 14, 2019, 02:34:48 am
Does anyone want to fix this for me? I will pay for your efforts and shipping. I will send you my x68k and my pi and RaSCSI so you can make it an external hdd to boot roms.
I have the following items for trade as well (all working fine): -SCSI2SD V5.1 -HXC2001 -ATX PSU replacement -SHARP X68000 EXPERT GY with ATX PSU replacement installed -An original MIDI Card for the computer
Last post by LowDefAl - October 12, 2019, 07:11:31 pm
First let's get it straight, the issue with Scart is that people assume that because it's got a Scart connector, it's compatible with any scart device. with our realising that the X68k outputs a TTL signal which most Start devices don't expect. So yes, you could potentially burn out a Scart TV or a Framemeister due to incorrect sync voltage, but on the other hand professional displays and OSSC don't care - I also would hope that many devices have the circuit integrity to be able to tolerate TTL even if they can't display it - at your own risk and all that. However this is a display device issue and has nothing to do with either the X68k or Scart as a connector/wiring standard being connected to it. Just please don't try to hook up to random TV's.
It's still up for debate if displays have caused a "feedback" of sorts, but only a handful of people have ever reported issues despite so many people using them with their machines that it's hard to get accurate data. There may be other factors involved. I've had shocks from VGA cables before, which could equally be a sign of issues.
What can happen is that wires can move under tension and short out other pins in the connector, usually due to bad soldering. This is not exclusive to Scart, I've done it twice and Scart wasn't involved, the most recent example was me changing a vga to bnc cable to use a DB15 instead of vga connector - no signal issues there. It still happened. It's only because fixing the cable didn't fix the image and I tested the cable on my PC98 where it worked fine that I knew it was the Sn74 had blown.
So yes, Scart should only be used if you know what you are doing, but blaming it for breaking systems is misleading and scaremongering even if that was not your intention. And certainly don't say only VGA should be used because BNC is equally valid and ideal for people with professional displays or video switchers. The system doesn't care what you use as long as it is wired properly and the display device can display TTL sync. It's only introducing shorts or 5v where it shouldn't go that will cause issues.
The SN74 should be checked as a matter of course, but even with a blown sync line it should still display something even if its gibberish. , so I'm inclined to think it's not that. The soft power circuitry still seems the most likely suspect to me. Even on my working system is doesn't always behave properly and we are dealing with a lack of user understanding which complicates matters.
Regarding Number 3, I'd say Yes it's very likely that the SN74ALS05AN needs to be replaced on the video board since you tried using a SCART cable earlier. There are many warnings on these forums about how SCART shouldn't be used with an X68000 - it's very likely to burn out both the SN74ALS05AN chip and the upscaler or display you're plugging into: