Tron video board question

[MitchO]

My Tron won't power on right now. While looking over the boards I noticed on the video board that the buss bar BB1 has several broken connectors. It looks like it may have been that way for a while so it may not be the cause of my issue but I am still wondering what does it do and how do I repair it? I tried to search the forums and google but didn't turn up anything.

Thanks,
Mitch

 

[demogo]

Measure the voltage coming out of the power brick. Any voltage?

If there is power coming out of the brick then measure what's coming out of the linear power board and report back.

Is your marquee lighting up? Does your monitor come on?

 

[MitchO]

The previous owner hacked up the harness to install a switcher so it doesn't behave like a normal machine power wise.
If I have the board unplugged all voltages are normal. With the board plugged in the voltages are around 1 volt at the switcher.
Any ideas about the buss bar question?

Thanks,
Mitch

 

[demogo]

The previous owner hacked up the harness to install a switcher so it doesn't behave like a normal machine power wise.
If I have the board unplugged all voltages are normal. With the board plugged in the voltages are around 1 volt at the switcher.
Any ideas about the buss bar question?

Thanks,
Mitch

Sounds like a short on the boards somewhere. Sorry to hear that the previous owner hacked up the power system; it was a good system. Could also be a bad power supply.

Was it working all along and just stopped?

 

[cdjump]

unplug the 2 cables between the ssio and the cpu and see if it boots then. If so, its probably one of the 3 10uF tantalum caps on the ssio shorted.
Edit- if one of the cables is misaligned it will cause it not to boot as well.

 

[MitchO]

It was working fine and then just wouldn't turn on one day. I am suspecting a short on the boards somewhere as well. That is why I was asking about the buss bar, as several of the connections are broken and it is kind of hanging in the wind. I didn't know if that would short it out.

I can try pulling those tantalum caps and testing them. That would definitely be the easiest fix.

Thanks,
Mitch

 

[cdjump]

just test them with an ohmmeter. Lift one leg until on ones that read as shorted.

 

[MitchO]

Finally had a chance to get back to this, tested the three tantalum caps and they are all fine.

Mitch

 

[cdjump]

did you try unplugging the ssio from the stack and see if it booted?

 

[MitchO]

Yes, it boots without the ssio board plugged in. Though the display is now upside down.

Mitch

 

[cdjump]

Test these 3 caps for continuity. If there is any, remove them.

 

[MitchO]

Thanks, I'll check it out.

Mitch

 

[MitchO]

Looks like CP204 10uf tantalum cap is shorted.

I guess I checked the wrong three caps the first time.

Mitch

 

[cdjump]

then just cut it off. the game will run fine without it. You can also replace it with a 10uf 16v or higher electrolytic cap. Its just a filter cap on the 12v rail.

 

[MitchO]

Had a spare 10uf 100v electrolytic in my spare parts bin. Swapped it in and Tron lives!
Thanks a lot for your help.

Mitch