S2000 issue

[foster]

Working on a friends S2000 (he has 2)  both 2006 or newer both 1270 boards
One working and one that refuses to boot correctly unless I unplug the door LED once powered on wait for VFD to show netplex down then memory testing, etcplug in door optic machine fine until next power off

At first due to how the MEI BV Status LED's was on I figured a netplex issue so unplugged BV, printer and hopper machine started upI kept chasing the netplex because as soon as I disconnect the BV from machine it would cycle and be ready other than no comm from machine
reconnected above no problem until powered down again

Already swapped questionable parts to working machine all good (MPU, VFD, and Legacy board) works in other machine

Disconnected door LED and Sound output connector at J19 motherboardmachine would start

Finally just disconnect door LED after MPU Red LED flashes a couple times and reconnect once VFD shows Memory Test
if I don't wait until MPU tries to start VFD never displays anything including netplex link down and sometimes board comes up but VFD remains off

[Stayouttadabunker]

I'd be checking pins on anything that connects...you'd be amazed because it's happened to me and I was very, very surprised.
Any crossed , bent or folded pin somewhere causes weird stuff to happen.

[foster]

I know its not a bent pin first thing I looked for when I pulled out both MPU's and legacy adapters

Machine A (working machine) is slow to start memory test, has to flash netplex link down a few times before it starts memory test - something that both machines started doing recently
When he first told me about the problems I thought MPU may not be making good connection to motherboard - not the case
Not the switch mode power supplies either (may be slow start but they both work in machine A - spare PS is even worse for startup
I doubt its wiring for either DC Voltages from power supply - 2006 or newer harnesses which means large wiring at least for some of the netplex ports on the motherboard
Tried a spare MPU in problem machine
Tried with Cabinet and door I/O disconnected (isolating reel back light controller, player buttons, 663 display, and other devices tied to senet
Had tried with VFD disconnected during a few power ups to see if it was the problem (it worked in working machine)


I am suspecting wiring issue in door harness, motherboard issue - bad component or something has gotten behind it, maybe switch mode power supply (but that means problem should have moved)


1 Power on machine
2 wait a few flashes of red LED on MPU is VFD off
3 unplug door LED for optics or open belly door
4 reconnect door LED or close belly door
5 may or may not see netplex link down a few times but will eventually see memory testing on VFD


When I decided enough was a enough to try today got a game change done on problem machine (B)
He will leave both on for now

[foster]

I think I have discovered the cause
The Fluorescent light power supplies for the fluorescent bulbs

[Stayouttadabunker]

Sounds like you were unplugging stuff to see what's drawing too much amps from the power supply.
A bad fluorescent ballast can do that.
Good catch Foster!