After switching out resistors and adding caps to my cable without luck I finally opened up the converter. Turns out the pins for red, green, and blue are not connected to anything. I could find three short traces that ended in unpopulated headers for resistors, so there was no electrical connection....

Yes I measured the resistance to 150 ohms on the rgb pins and around 75~80 on the csync.

I've seen designs recommending up to 330 ohms on the sync pin on machines without a modulator.

I'm having problems with getting an image through a SCART to HDMI scaler I bought to connect my Mega 4 to a monitor. There is a faint image coming through, so I'm not sure whether it's the output, the SCART cable or the upscaler itself. IMG_20171006_175044.jpg Could it be that the scaler doesn't sup...

It also could explain what seems to be cut traces on the motherboard next to it.

I found it. It looks like a fix to synchronize the /BGACK coming from the blitter to the CPU clock.

This morning, this Mega 4 arrived in the mail. IMG_20170922_114402.jpg I haven't had a chance to hook it up yet (have to go to the basement an scour for cables, etc.), but the seller said the floppy drive is not working. (Floppy LED lights up but it does not read any floppies.) I have a Gotek in my ...

Does the ST PSU work in a Mega ST (the pizza box ones, not the Mega STE) as well or does it have different requirements?

exxos wrote: ↑Thu Sep 07, 2017 10:25 am Noted in that doc, 64 clocks for bus error.. always wondered that!

Yup. I think it's handled by the GLU chip. If I remember correctly from the ASIC schematics, it looks like it monitors the /DTACK line and issues /BERR after the timeout has expired if /DTACK is not asserted.

I think I get what I had wrong. The pinout on pinouts.ru is different. It has A10 and A11 where other pinouts list CAS2 and CAS3. Mystery solved! :) Edit That previous pinout was something called "72pin simm with ECC". It's not the first time I've been fooled by the wrong diagram. The corr...

Connects up the same as a 4 MB 72 pin simm. Yeah, I never understood those hacks either. I see you used to have a 72 pin SIMM kit available as well (and I think I might have asked a similar question before.) If I'm not completely wrong, 72 pin SIMMs do not have ways to target individual bytes . How...