wms 550 no video

[Tkharper]

I seem to have a lot of WMS 550 CPU’s that are giving me a start up bong but no video. I have noticed that almost all the boards are the ones with the secondary video board attached. Could that board be the problem?

[dragster73]

The Bog noise is produced by the Sound section independent of the CPU part of that board. This means the means the sound could boot without the video if I remember correctly.  What size Eproms are you trying to use? 27040 or 27080?

[Tkharper]

I’m not sure the size eprom ( I actually am not sure the difference). I will post a picture as well to show what I’m using. All my software is this size.

[rickhunter]

That board is missing the XU3 chip, or did you remove it to clear?

[Trisail]

Plus - the blue tape on the video PCB says < no signal >

Unless of course you placed that there for your reference.

If you are testing the MPU boards with the XU3 Eprom missing - I would start there by installing one like Rick suggested. (I believe it is needed for the machine to boot, actually I'm pretty sure it is needed)

[Tkharper]

I placed the blue tape there saying no signal, but that tells me also no video. I have the XU3 chip as well, I took it out to clear. If I place the XU chip or the clear chip I’m still getting no video. I get a start up bong as if everything good but no video. I have a good handful of boards doing this. I’ve tried different software to rule out that. I’ve taken good software off other working boards and still no video.

[Trisail]

It sounds to me the video PCB would be the most likely place to start. You said you have many boards. Do you have many video boards also with the same problem? Or do you have a large number of MPU boards that require the video PCB and you only have one or a few video PCB's?

If you have many MPU and many video PCB's, have you tried to swap them onto a known working set in a machine one at a time? IE - known good set ( mpu & video ), swap just the video PCB and see if it works? Then swap the MPU using the known good video PCB and see if it works? I would do that and label the good ones and bad ones. Then you can see about repairing the bad ones.

Your original post asked if the video PCB might be the problem. This would let you know what boards are what. Then you can determine if you can try to repair the bad ones yourself or send them to someone for repair.  Maybe some members that have repaired these could chime in with suggestions on what to do to try to repair them.

[Tkharper]

I was able to find a good working video PCB and changed it out. After doing that the board did get video to it. So it seems I have about 8 MPU’s that will need working PCB’s. Thank you all for all the post to help me out. I kinda of thought that was the problem from the get go but was second guessing myself. Much appreciation!