6-in-1 switcher PSU voltage concern

sleepyhed

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Hi everyone,

I'm running a 6-in-1 switcher (with a NoMote which is friggin' awesome!) in a dedicated MK II cab with the following games:
-MK
-MKII
-NBA Jam TE
-Tekken 3

All the Midway games randomly restart during gameplay. Sometimes right after power up. Other times when I'm about to sink a 3-point buzzer beater in the 4th quarter to defeat the Golden State Nuggets. :) From what I read this points to my 5 VDC being too low at the PCBs. No PCBs are directly inserted into the switcher (I don't think there's room or enough structural support). I mounted the PCBs to the walls and am using JAMMA extension harnesses so there's definitely a decent amount of wiring for voltage drop.

What would you say the best target voltage at PCBs is given this setup and do I need to worry about hurting anything if I turn up the voltage at the PSU so that the PCBs get that target voltage? Might the switcher or Tekken 3 have any issues?

Also, I don't think it matters but since I thought I read someone saying that their Turbo Ninja ROMs acted goofy, I have Turbo Ninja in MK and Challenger in MKII and 2.0 in NBA Jam TE.

Thanks!
Cj
 
I can answer one of these questions. Your switcher itself won't be hurt if you turn up (or down) the voltage. It's safe across a very, very wide range. Your game boards on the other hand are far more sensitive...

You just need to be careful as you're turning it up for one board, that it isn't too high (or low) voltage for the other 5 boards.

If it's a matter of voltage drop across your extension cables, it's far safer to use a larger gauge wire (or multiple wires) then it is to crank up the voltage on the power supply.
 
this points to my 5 VDC being too low at the PCBs.
I need to worry about hurting anything if I turn up the voltage at the PSU so that the PCBs get that target voltage?

had a jr pac board that I had to turn the switcher up to +8 just to get +5 volts on the board and then it worked !
board came from a salt water environment and the traces were oxidized but my point is that its fine to turn the switcher up but different size boards can also require more or less +5v
one board you might find you have to turn the switcher up to 7 to get the +5v but another board might require +6v dc
or, another board might only need 5.5v and that's why you get resets

check along the way for correct +5 as voltage drops from weak pins or dirty finger edge connectors can change the value at the board

remember that 5.25-5.35v + can damage chips good luck

if only all boards were the same size and required the same voltage from the power supply but sadly...good luck
 
What extension cables are you using? Some cheaper ones have thick cables but in fact the actual leads inside the insulation are way too thin. If this is the case, replace the +5v and GND cables in the extension cables to something with thicker leads in it. Or add additional cables that run alongside the existing ones.
 
Thanks for all the replies so far. I cleaned all the edge connectors prior to install and know all games work fine individually. I forget the wire gauge but I'm using the better extensions from Bob Roberts (paid a nice penny for the quality and the convenience but they made the install SO much more flexible). When I get some down time I'll incrementally turn up my power supply while checking voltage at the board. Hopefully all will get to 5v before one gets to 5.2v!

Appreciate the help. I'll circle back with my findings.

Cj
 
Finally got around to checking and tweaking the PSU +5 VDC voltage.

Location______Before__After__Delta__Drop
PSU.__________5.33___5.54__.21___---
MK1 ROM______4.79___5.01__.22___.53
MK2 ROM______4.84___5.02__.18___.52
Jam TE ROM.___4.68___4.94__.26___.60
Tekken 3 edge__4.85___5.15__.30___.39

No surprise why they were resetting, especially NBA Jam TE!
I measured Tekken at the board traces on the edge connector because the board was hard to reach and I didn't see a familiar ROM to probe.
It's interesting how some of the games' deltas are greater than the PSU's delta. Weird?

Tekken 3 manual says +5 VDC +/- 5% so with 5.15 being +3% I'm going to stop here and see how the games behave. Initial results look promising!

If you see anything I should be concerned with or have more suggestions, please let me know. Thanks!
 
Dangit, I spoke too soon...

After leaving the games on a while, they began resetting again so I checked voltages. The PSU is still putting out 5.54 so nothing changed there. I measure NBA Jam at a ROM while it's in a reset cycle and it's 4.72. Wtf!

I first thought that my (possibly original to the cab) Peter Chou power supply's voltage was drifting, but no, that's exactly where I set it. Could it be current related?

Is it possible that something in my 6-in-1 switcher or even on the games' PCBs are intermittently causing voltage drop, maybe after they have been running for a bit?

Tomorrow I will really get in there and check voltages at all the input/output spots including the jamma switcher and see if that reveals anything obvious.

Am I overlooking something?
 
lots of voltage drop there
I would test along the way and try and detect where the voltage drop is happening

also would install brand new switcher. lots of money sitting there in game boars to be using old switcher

leave resetting board on until it resets, then with the back of your finger and feel the chips and see if any are getting hot. could be when a chip gets hot it pulls down the voltage which is why the chip is getting hot. maybe you find problem chip and can fix by adding a heatsink to wick away the heat fast enough for the game to quit resetting

I would shorten power wires, even all of them. have it all be custom job instead of long messy lines

test resetting board all alone and see if it resets or maybe its fine and no hot chips. could be some problem with the switcher or the way you have it wired.
sometimes when I'm hooking up 12v for the sound in a cabinet/wire harness, I can run the coin door lights off the connector no problem and sometimes I cant and I don't know why. in the cabinet/harness that doesn't like it I can run the 12v directly off the switcher and all is well. now I put additional ground to with the 12v so as not to go through harness which I think shouldn't have to but seems to work to have coin door and ground separate I don't why good luck


.
 
The bulk of the voltage drop (as much as 0.6v!, 5.55 --> 4.94) is happening all the way at the front end of the circuit between the power supply and the other end of the 1st jamma extension harness/6-in-1 edge connector. The setup in sequence is power supply --> original MK II jamma harness --> 1st extension harness that goes to the 6-in-1 switcher. After that, the voltage drops between the 6-in-1 switcher, extensions harnesses, edge connectors, and chip legs are small.

Any thoughts on why the very first extension would be such a huge voltage bottleneck? It also seems to be time related in that games work but after a bit the drop and resetting occurs. Chips heating up was mentioned but this drop is before any chips. Could the original jamma harness conduct more poorly after warming up? Maybe the original harness is the culprit.

Before I start cutting up any of the extension harnesses, I'm going to try swapping out that first one in case it is defective. All the others running between the 6-in-1 to the PCBs seem to be dropping an acceptable amount.
 
When the wires heat up, that causes more resistance and voltage drop.

You don't want to cut anything up.

You want to add more wires to 5v and ground on your harnesses. You should have 3x 18awg wires for 5v and ground for starters. This is on each board.
 
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