Recent content by hkz

Greetings everyone, I got another dead MVS that is proving to be annoying to get running. Might have another dead custom IC on my hands, but I'd like a second opinion before I put this in the pile of scrap boards. MV1FZ Motherboard, when powered up it shows bursts of random lines on the screen...

Hi All, Between a pile of junk I recently obtained, I found a SEGA STV. Now, this board is probably junk for several reasons, but I don't like the idea of not at least trying to save it :) 1) The board suffered water damage, it's not severe but it's all across the board. Probably left in the...

Hello everyone! It's been a few years since I posted here, but I've recently recovered a small lot of defective MV1 boards and started dabbling with them again, for fun! WARNING: Wall of text incoming! First of all, I know these boards are relatively cheap by now, and it's economically more...

mjs256, thanks for the offer, but I also had a YM2610 laying around... so I decided to remove and socket the one on the 1FZ. I think i got lucky: as soon as i replaced the chip, the error went away. Now the diagnostic bios shows ALL TESTS PASSED I've yet to try with a game, but this screen is...

I finally received the diagnostic cart from JAMMA NATION/Xian Xi, and I used it to test the 1FZ. The first screen I get when i start the board with cart inserted and pushing D says When I push START to continue I get to a screen which says I previously desoldered and read the SM1 rom with...

Fixed! I rewired a 5C6408 8k SRAM module in place of the dual 2114 contraption (which BTW, was used to provide 1024 x 8bit instead of 1024 x 4bit like single 2114 do) and it works perfectly: no flickering or bad pixels. I think this repair is concluded :)

Update: a good one :) I added all the missing filter capacitors to top and bottom board (a total of 42!)... but that didn't solve the problem: the sprite still flickered. At that point I was without ideas, then I noticed that flickering/bad pixels appeared only on even lines. Got the schematics...

Colors fixed. Apparently the RGB and CSYNC lines are reversed in respect to what the original GnG board pinout says: what was on the parts side got placed on solder side. I wonder if it was just to annoy people :P Anyway, time to check sound, controls... and pass on to another board.

As you can see, a color channel is missing: it's because I couldn't find a single 74LS367 in the whole house :-P But it works!!! \o/

Here are two higher res photos of top and bottom board. The sockets replace the two chips that took 12v on their output ports, the other pink marked ones are the ones that are directly connected to those (which will need close scrutiny with a probe, should problems arise). I checked original...

Hello everyone again! I've recently recovered a bunch of board from a closing up arcade shop. While the boards were sold as broken, some of them are fine... some are indeed dead. Especially the one I’m working on now. This board is from an unknown game, and I think the guy that sold it killed it...

Hello, I've already posted about this in the introductory section, but for the sake of completeness I'll try to recap everything important in here, and hopefully the experts in this forum will be able to shed some light on the matter. A few days ago I recovered two MV-1FZ boards in non-working...

Finally, I can post! Hello everyone! I got here because I was searching for help in repairing two MV-1FZ I recovered from a box of boards found in a closing arcade shop (btw, stay on the lookout for a post on this in the tech section later today ;) ). In the end I've been able to fix one by...