Tron/MCR Power Supply Issues, White Screen of Death

Segagee

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Tron/MCR Power Supply Issues, White Screen of Death

Got a little surprise in the mail today, some shiny new Tron ribbon cables from Bob Roberts. I figured getting these was a good step towards getting the game up and running, as it was dead when I got it.

I've really only done minimal work on the machine so far, IE testing for voltages and replacing the power cord, the old one was in really bad shape.

Before installing my ribbon cables, everything was getting power except the gameboard as it was not connected (obviously). After installing my ribbon cables and re-connecting the game board, I am still getting a white screen with a nice loud hum from the speakers. Still no power to the game board. I re-installed the ribbon cables twice, double checked my connections, and still get the same result.

I've tested my power supply according to an MCRII manual found on the forums, and am getting in the neighborhood of what should be the correct output voltages. With this in mind and all my connections hooked up I am still confused as to why the game board is not getting any power.

Maybe it's time to get a switcher/and MCR adapter? I didn't want to attempt Bob's rebuild kit as I figured I might mangle up the PS more on accident.

If anyone has a pic of their Tron PCB hooked up that would be great so I can verify all my connections are correct, I am pretty sure they are though.

Thanks for any help and in the meantime I'll be out in the garage...:D
 
Tested with or without the pcb connected ?

Good point, I thought this made a difference but was not sure. When testing with the PCB connected, +5 volts is dead. To my understanding this supplies power to the game board, so I guess my problem makes a little more sense now >_<. Adjusted both pots on the board to try and bump up the voltage but this resulted in no change.

I suppose there is no other way around this other than a rebuild/new supply?
 
Bos ribbons

If you got the ribbins from bob and they have 2 female headders on each end. Not both of them have continuiy to each other or to the corresponding headder on the other end. It might have continuity from the bottom row on one end to the top row on the other end. Or top to top. There does not seem to be any pattern to this. I have got 3 sets from him and they are all like that. Ohm out the ribbons and see if that is causing some or all of your problem. They are usable. You just have to know wich row to plug in.
 
you can also check voltage at the main harness where it connects to the pcb. iirc, pins 3,4,5, and 6 are +5. but doublecheck that in a manual, not 100% on that.
 
the easiest way is to check at the bottom left corner, and top right corner of one of the eproms on the ssio (top board on the mcr stack). The top of the chip is the end with the notch. The eproms are the two chips with stickers covering the clear window.

Now, having said all that, have you tested the fuses both in the power brick, and on the power supply pcb?

The hum could be cold solder joints on the amp board, among other things. But, first, you need to verify that your fuses are good (with a meter), then verify power to the power supply pcb. After i'd verified where i was losing power, then i'd start to think about rebuilding or replacing the power supply pcb.
 
Make sure you check for cold solder joints and/or reflow all those connector pins. I had graphics problems on mine with the new ribbon cables until I reflowed all the connections.
 
Thanks for all the tips guys. Been going over everything again this morning and still no +5, gave the power board a good cleaning but the corrosion on the connector pins and components has already taken its toll.

I have yet another question: Is it possible to use an old-style AT (not ATX) switching power supply in conjunction with one of those MCR adapters to supply power?

Pulled one out of an old computer this morning, tested it with load, and it checked out good. The specs on the supply are 115/230V selectable, 250W, +5V @ 25amps, +12V@ 10 amps. The supply also has -5 and -12 both at .5 amps but to my knowledge use of these is not necessary.

The specs seem similar to the ones shown here:

http://arcadeshop.com/mcr/mcr.htm

Just want to double check before I track down one of these adapters, wire it in using said PS, and either fry something or not have enough power.
 
Adapter

Thanks for all the tips guys. Been going over everything again this morning and still no +5, gave the power board a good cleaning but the corrosion on the connector pins and components has already taken its toll.

I have yet another question: Is it possible to use an old-style AT (not ATX) switching power supply in conjunction with one of those MCR adapters to supply power?

Pulled one out of an old computer this morning, tested it with load, and it checked out good. The specs on the supply are 115/230V selectable, 250W, +5V @ 25amps, +12V@ 10 amps. The supply also has -5 and -12 both at .5 amps but to my knowledge use of these is not necessary.

The specs seem similar to the ones shown here:

http://arcadeshop.com/mcr/mcr.htm

Just want to double check before I track down one of these adapters, wire it in using said PS, and either fry something or not have enough power.

It will work fine with the adapter except that it may have a hum when you go that route.
 
aDAPTER

Alright, good. Hopefully the hum is only slight as that will not bother me.

The adapters seem to hum worse on Spyhunter and Trons unfortunately. Kicks and Satans Hollow are not as noticeable for some reason. I have only tried the arcadeshop version. Mark Spaeths are supposed to be better about the hum.
 
Spaeth's hummed in Spy Hunter as well. I tried 2 switchers in my Spy Hunter (one of them Arcadeshop's) and they both sucked because of the HUMMMMMM.
 
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