T&F boots to zero's

GoneMad

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Just got a track & field off fleabay. Was listed as sounds cuts in and out. Booted it up to a screen of 0's. So far, I cleaned the edge connector, removed, cleaned, and reseated all removable chips, and still boots to this screen. Should I be starting with the CPU, eproms, sram or logic chips?

IMG355.jpg
 
Make sure the voltage on the board is at least 5.0V, maybe a little bit more. Measure at the far end of the board from the edge connector, on both the top and bottom boards.
 
Just went to hook up the probe and check out the program roms, and when it booted back up, it seemed to boot to part of the title screen with a little bit of the name entering screen, with the odd random zero here and there. I didn't have my phone to snap a picture, but the eproms all seemed to be probing active on pins 22, which means the data is being read? Tried to boot again and just booted back to zero's. Could this be corrupted roms?
 
Just went to hook up the probe and check out the program roms, and when it booted back up, it seemed to boot to part of the title screen with a little bit of the name entering screen, with the odd random zero here and there. I didn't have my phone to snap a picture, but the eproms all seemed to be probing active on pins 22, which means the data is being read? Tried to boot again and just booted back to zero's. Could this be corrupted roms?

More probable bad connection to them or bad sockets.
 
More probable bad connection to them or bad sockets.

Kinda hoping it's not bad sockets. They can be a real PITA to remove without a real good desolder station. I did try flex the board a bit and push down on the program roms with no effect. I do have an extra set of program roms I will swap in just to see if they make any difference.
 
Kinda hoping it's not bad sockets. They can be a real PITA to remove without a real good desolder station. I did try flex the board a bit and push down on the program roms with no effect. I do have an extra set of program roms I will swap in just to see if they make any difference.

They are not too bad if they are the real cheap ones, you have to pull off the plastic part off first. That makes removing them 10x easier than trying to pull them off as a whole. You just pry the socket, as if it was a rom and the plastic comes right off. Then just remove the pins, one at a time, and de solder the hole. Quick, clean, and easy with very few trace problems.
 
I will try replace the sockets anyway. I swapped out the chips with different set and still same. Tried pressing down again on the sockets and nothing.

Without good sockets it might have worked for a bit then at the worst possible moment crap out. It is better to just replace them and if you are not comfortable doing this the local tv shop should be able to do this for you for a lunch and some $$. It is kind of nice to rule out the sockets but be sure to use dual wipe sockets and good quality ones. Do it once and be done with that part of it.
 
They are not too bad if they are the real cheap ones, you have to pull off the plastic part off first. That makes removing them 10x easier than trying to pull them off as a whole. You just pry the socket, as if it was a rom and the plastic comes right off. Then just remove the pins, one at a time, and de solder the hole. Quick, clean, and easy with very few trace problems.

Unfortunately these don't look like the cheap ones. Look to be one solid molded piece. I will try one and see how it goes.
IMG356.jpg
 
Those don't look like the real cheap ones I have seen on the Galaga boards and I am not real sure I would replace them.

can you post a pic looking down into the socket, I want to see if there is connecting pins on both sides of the socket and not just on one side of same pin.
 
They actually look like they should be replaced, you see how only one side has the connection to the socket. A better dual wipe socket will have pins on both sides of a single pin hole. Them sockets are a bit harder to get the plastic off of but not impossible. Just don't damage the board trying to do that.

I can't believe that there is not a better video on how to remove these sockets. Here is one for a 40pin processor type chip but he cuts the legs off first.

http://www.youtube.com/watch?v=47xGYT-QGLI

EDIT:

Did you notice the ending 4 on that part number it is the speed and if you can use faster chips that would not hurt. I don't think it would matter much on that game but some need faster chips. Make certain they are all about the same speed.
 
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OK, Hooked up the logic probe, grabbed the schematic and started with a working board. Checked the ls245 next to the cpu at 3B. All compared the same with the good pcb and bad one. Move on the the 2 ls244 at 5C and 5D. Both pcb's have the same results with 5C, but when I check the 244 at 5D, pin 16 on the bad pcb was stuck high. On the good pcb, it was active. Could this be the spot or area that is causing the problem? Need a little more expert help here. Thanks
 
After checking the data sheet on the ls244, pin 16 is an output. All the inputs seemed ok so I pulled it out and replaced with a new one. Voila! Booted up no problem. Just have a few graphic glitches to figure out. Seems the numbers in the world records in the game screen and the high scores are whacky. As stated earlier, all chips were removed and cleaned. Only problem left with this board is this and intermittent sound, which shouldn't be heard to diagnose. Just want to get this graphic thing fixed.
IMG365.jpg

IMG364.jpg
 
OK, Hooked up the logic probe, grabbed the schematic and started with a working board. Checked the ls245 next to the cpu at 3B. All compared the same with the good pcb and bad one. Move on the the 2 ls244 at 5C and 5D. Both pcb's have the same results with 5C, but when I check the 244 at 5D, pin 16 on the bad pcb was stuck high. On the good pcb, it was active. Could this be the spot or area that is causing the problem? Need a little more expert help here. Thanks

After checking the data sheet on the ls244, pin 16 is an output. All the inputs seemed ok so I pulled it out and replaced with a new one. Voila! Booted up no problem.

Sounds like you're a natural with the logic probing.
Good work isolating and fixing.

Not really a graphics glitch, just some trash in the RAM. Reset your high-scores and that should go away.

+1.
A quick google search says it's dipswitch bank 2 switch 5 to do that.
 
Not really a graphics glitch, just some trash in the RAM. Reset your high-scores and that should go away.

Tried this, everything cleared up. While I had it out, replaced the caps in the sound area, put it back in the cab, fired it up and played a few games with no problems. Thanks guys. Another one to push back against the wall.
 
Tried this, everything cleared up. While I had it out, replaced the caps in the sound area, put it back in the cab, fired it up and played a few games with no problems. Thanks guys. Another one to push back against the wall.

Glad you got it working and you can see how important it is to have a working set to compare it (non working) to.
 
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