John's Arcade Forum - Classic Arcade and Pinball Collecting and Restoring Discussion Forum - RETRO MAME - Nintendo Vs Forum

I need some help repairing my WWF Wrestlefest pcb and thought some of you clever people here might be able to help steer me in the right direction. It's a genuine Technos pcb not a bootleg.

The board was working with some graphics glitches but is now playing blind after I replaced a bad 6116 ram chip at IC24 on the board. I had problems removing the chip and lifted a couple of pads and damaged some traces in the process. I have repaired all the traces and triple checked continuity to each area I fixed but no video is being output to the screen. I've made sure the replacement chip is the correct type and output and used my logic probe to check that there aren't any stuck pins or faulty gates but everything appears to be working according to the datasheet. Voltages at the board are fine, im getting +5v, -5v and +12v. The game plays all music and sound effects, coins up, starts and the controls function as they should.

I know  it isn't a monitor issue as I have it running on my jamma test rig with an LCD monitor through a vga converter and it worked previously with this setup. I've also swapped pcb's on my test rig and they all output video fine.

I'm certain the problem relates to the botched removal of the IC I did but with no available schematics for this game I can't be sure and don't know what areas to check next? I would normally probe for video sync signal, v-blank etc if I had the schematics available to me but without them I am essentially poking around in the dark.

What sort of things would cause no video output on a pcb? All I've been able to find from Google searches is info about bad monitors being the cause of games playing blind but virtually nothing when the pcb is at fault. It's driving me mad trying to figure out the problem so I'm hoping someone can help?

Thanks in advance.

There are generally video chips to check on a PCB and of course the traces that run to them. I think you are more technical with these than I am, but you should be getting video signal to the edge connector. So I would think you could start at the edge connector and follow the lines backwards from there to where the video is coming from on the board. Does that make sense? Hope that helps, and hope you get it fixed, and HOPE YOU UPDATE US!  ;D

Thanks for the suggestion. I've decided to replace the ram chip and put a socket in just to be doubly sure. Also redoing the trace repairs for good measure. If I don't see any change then my next plan is to work back from the edge connector as you have suggested. I'll update if any progress is made.

Picture has been restored! I redid my previous trace repair, fitted a socket for the ram chip, replaced the ram, fired it up and to my relief the picture was back! Such a relief. The board looks like crap with all the repair work but as I don't plan on selling it, I can live with it. I'm still having some issues with the background sprites having vertical lines through them and I will address those next but in the meantime I'm just glad to have any graphics at all!

More progress made today. The game was playing with jailbars through all the background sprites so I looked to the eproms next. I Verified all the eproms against mame and they checked good. Next was the mask roms at ic 1 and ic 2 on the pcb. A bit of Google searching revealed that these had the same pinout as M27C400 and MX27C4100 bar A17 which is not connected to anything. Dumped the roms and tested them to find they didn't verify. At last some progress. 

I put my dumped roms 1 at a time in to the mame zip file for Wrestlefest and loaded it up. Bingo! With my ic 1 dump I was able to replicate the jailbars exactly. It seems that bit-rot has set in on the mask roms so I need to burn a new one using the correct mame files. Unfortunately I don't have any in my parts bin so have ordered one off of eBay. Not a cheap part either cost me around £23 for one eprom!  Once it arrives I shall update and hopefully get this board back to full health! 

The eprom arrived and I programmed it with the info from mame. I swapped it out for the Rom at ic 1 and turned it on to find the background issues had gone.....unfortunately a new graphical problem has appeared to take it's place  

There are now some blocky sprites in the top section of the screen in the crowd and in the background on the title screen that were fine before the new Rom was put in. I figured it must be a bad burn so I erased the eprom and programmed it again but this time the glitches were slightly worse!!

I pulled the eprom again to verify it against the mame file again. I had already done this a couple of times after the write process had been completed to double check, but figured it couldn't hurt. I loaded the mame file in to the buffer and verified it against the chip I had programmed....it verified good. Then I decided to use romident on the mame file...it recognised it as:

IC1 'WWF Wrestlefest Technos'.

Then I loaded the file that I read from my written and VERIFIED chip;

'File not recognised'!!!!

Huh?? So apparently the information on my chip, which my eprom programmer keeps telling me is exactly the same as the mame file, is not exactly the same according to romident? I have never encountered this before and can't find anything so far from my Google searches to show anyone else has either. If anybody can shed some light on what is causing this I would appreciate it because as of now I am stumped as to how to proceed.

If I can't solve it I'm going to have to ask if anyone has a spare working IC 1 from a Wrestlefest board going spare because that is looking like the only alternative.

Did you ever get this fixed? I have jailbars on my Wrestlefest also. But haven't checked IC 1 or 2 yet.