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Sega Rally Championship 1995 - PSU Issue?


Milodrinker

Question

Hey guys, need a little help with this one.

 

Recently purchased a 1995 Sega Rally Championship Twin Machine however; there are a few issued (to be expected with these machines)

The machines graphics/controls/screens are perfect yet the graphics on machine 1 are constantly freezing after playing for a few minutes.

When the machine freezes the screen will either hold on one frame of the car or (if it’s on the intro video) will go blue still displaying the HUD, and with music continuing to play in the background in both instances.

After letting the machine run and switching it on and off throughout the day it eventually runs perfectly and won't freeze at all.

I can see the previous owner has added some silicon glue or adhesive to some of the capacitors so potentially these could be the route of the problem they were trying to bodge?

All the inbuilt memory tests come back perfect and no other issues apart from the freezing can be found.

I'm thinking its potentially a capacitor issue or a voltage issue with the 5V output from the PSU but looking to see if anyone else has experienced this as I can’t find any previous mention on AA.

Have attached photos of the power supply and capacitors that were messed with as well as photos of the display when it freezes.

In addition; on the 1st start-up of a day the screen presents as the final image which looks almost like a screen test and the machine won't begin till it’s turned off and on again.

Would appreciate any help/suggestions at this point.

 

- P.S if anyone has diagrams/schematics of the motherboard/PCB's that would be super helpful

 

Cheers ^-^

 

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Locate PC101 , it looks like a resistor next to the only INTEL IC on the main board, measure across this and you should get 5.0v , I am assuming this machine is a twin, if so swap the main board to the other side and see if the fault follows the board, if it does you have a board fault, it the fault doesn't follow then it's a power supply issue.

The power supply is the black unit in front of the main board, the images you have shown are only the Audio Mixer and Sub Amps, they are nothing to do with the power supply, the silicon is factory and put there by Sega to stop the caps vibrating out.

It's amazing how many of these still have original untouched power supplies in them, the caps are rated to last between 8 to 10 years, the machine is 26 years old so if they are untouched the caps will have completely leaked all their contents and dried up into empty shells, The game needs very clean 5v DC , even with all the caps completely gone you will still read 5v but it will mostly be unfiltered AC passing through which damages the boards and of causes freezing or no boot.

Yes they can be rebuilt and the boards can be repaired if they are not corroded.

Edited by Jomac
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