Swapped a Jamma board and now the monitor will not power on (19K7201)

[FireZoneBlitz]

I swapped in a different (working) Jamma board on one of my Marvel cabs with a WG K7201 and the monitor didn't power on. I swapped it back to the original CPS hardware and it's still a no go. Boards work find (pay blind) and I'm still getting AC power to the monitor. The fuse looks good on my meter continuity. Is there anything I can check before pulling the chassis out and going over it? Not sure why a different board would cause a monitor issue - no previous issues with this monitor. Just making sure there isn't something else easy I should check before tearing it apart.

 

[SillyB]

If you have AC to the monitor, you can check if you have raster by turning brightness up really high and see if your black tube gets lighter and/or you see retrace lines. People say look for neck glow but sometimes it's very hard to see and I like this way better. If you have raster but no picture you aren't getting signal.

Chances are you have loose wires in your jamma harness going to the monitor. I've seen this before and just had this exact thing happen a week ago. I pulled the CPS2 out to clean the area, put in a test PCB and got no picture. Upon inspection I found bad connections in the molex to the RGBGS wiring. Cleaned and tightened the connection and I was back in business.

 

[mecha]

I've seen some strange behavior from a K7203 with no signal applied, the monitor would shut down after making hissing sounds. apply signal, it works. but then later I tried running with no signal again and it ran just fine. I'm just convinced this was a very flawed model! I have no rational explanation for that, but your problem sounds like what I had.

I agree with SillyB's method, that's how I was trained to turn Screen up. however I possess the ability to hear 15 KHz chatter, I can tell when they're actually running. if your monitor's making ticking sounds then you have a different problem.

 

[FireZoneBlitz]

Thanks for the advice! Doesn't look good so far. I pulled off the jamma connector, cleaned and tested continuity to both ends. Everything looks OK. I also pulled the monitor side and checked those. I did try maxing out screen brightness but I don't see anything even in complete darkness. The monitor gives off zero sounds at all.

 

[SillyB]

Over the years I've found I can often get ahead of myself. The best troubleshooting is following the A/C. Check the plug, power wire, fuse block, power switch, isolation transformer, chassis fuse and ground, before pulling anything out. I've found bad power switches, fuses that looked good but were blown, no continuity in strange places... all kinds of minor things.

If you do have A/C at the chassis and no raster and no blown fuse you'll probably be best to follow the flowchart.

 

[FireZoneBlitz]

I've got a spare monitor that I'm going to swap out tomorrow. Will go through the flowchart for fixing and I'll let everyone know if I find anything.

 

[FireZoneBlitz]

I wanted to update this since it looks like a lot of people have troubles with these model chassis. I recapped the board, swapped out the cracking flyback, replaced the HOT (I had a spare) and so far I'm not getting any voltage at all. It looks like this has its own mini ISO transformer on-board and the manual states it doesn't need one. I'm going to try wiring it direct - I've been testing this on a test setup through a separate ISO. I checked the flowchart and everything else is fine. I'll update once this is fixed.