I recently got a couple of Wavy23 systems off eBay in a late night impulse buy. One works and one doesn't. The one that doesn't powers up but only gives me black video. Pushing caps lock doesn't cause the light to change. I've been unable to find any schematics, but from reading the forums it looks like you guys are very much experts on repairing all kinds of different MSX systems.
What I've done so far:
- Checked the voltages: +5V, +12V, and -12V all read ok.
- Used logic probe to check that the Z80 is getting clock and it is
- Tried piggybacking the six 4464 chips with known good ones, no effect
- Used the logic probe to check that there is activity on the data & address lines
- Tried the Arkanoid and Xevious cartridges I have but still black video
When it first turns on the Z80 pulls /HALT low and /RESET is high. If I let it warm up for a bit and hit reset /HALT goes high and stays high, but it still doesn't boot up. My guess is that the Z80 isn't finding the ROMs to start the boot code.
Tools I have available: multimeter, logic probe, Saleae Logic 16, and a very old purely analog Tektronix 2 channel oscilloscope. I do have some experience with repairing old computers and arcade machines. I also have some of Marcelo Zoffy's EPROM boards and can burn ROMs if there's a diagnostic program that will fit I should try.
Any assistance you can give would be greatly appreciated!
