On our paragon, the voltages test good on the transformer bridge rect board.
The mpu gets a quick flicker and the machine occasionally gets the 1 LED flash. Occasionally it also does not and anything from a solenoid firing to a sound board bong to nothing occurs with each power on/off cycle.
Is it likely that the original u1, U2 and u6 have become corrupted? Or is another scenario likely?
Is there any battery damage from a leaking battery?
Also: http://pinwiki.com/wiki/index.php?title=Bally/Stern#First_flash:
Yes, there was damage but it has since been repaired. I accidentally shorted f2 and f3 on the transformer board which I'm suspecting corrupted the original roms.
Quoted from ForceFlow:Is there any battery damage from a leaking battery?
Also: http://pinwiki.com/wiki/index.php?title=Bally/Stern#First_flash:
Quoted from EEE:On our paragon, the voltages test good on the transformer bridge rect board.
The mpu gets a quick flicker and the machine occasionally gets the 1 LED flash. Occasionally it also does not and anything from a solenoid firing to a sound board bong to nothing occurs with each power on/off cycle.
Is it likely that the original u1, U2 and u6 have become corrupted? Or is another scenario likely?
Make sure the clock is running. You can get erroneous LED activity when the CPU clock is bad. CPU P3 and P37 should be pulsing around 700KHz if you have a DMM that can read frequency or a scope. Easy to check if you the tool before you start pulling ICs. DMM on vdc will read CPU p3 and P37 between 2.4 and 2.6v, not a true test though...
MPU U15 is typically the first thing to go out when there is an over voltage occurrence which will kill the clock.
If you have any other Bally games with the same ROM setup, ie U2 and U6 are the same kind of chip, you can swap between another game and see if it boots up.
Quoted from EEE:Yes, there was damage but it has since been repaired. I accidentally shorted f2 and f3 on the transformer board which I'm suspecting corrupted the original roms.
Ouch. 
F2 is the display voltage, and F3 is the logic voltage.
In that case, pretty much every IC on every board connected to the +5v logic line could be suspect--not just the ROMs. The CPU chip could be suspect as well, so don't overlook that.
[edit]: I'll defer to barakandl's expertise. 
Quoted from ForceFlow:Ouch.
F2 is the display voltage, and F3 is the logic voltage.
In that case, pretty much every IC on every board connected to the +5v logic line could be suspect--not just the ROMs. The CPU chip could be suspect as well, so don't overlook that.
[edit]: I'll defer to barakandl's expertise.
That would short high voltage to the 12v line. The 5v regulator would be between the MPU and this HV to 12v short so hopefully the regulator ate up the high voltage with out much problems.
When over voltage hits the bally MPU, usually U15 explodes and the fuse blows. I have fixed that more than a few times when someone mixes up a connector that throws 12v down the 5v rail. u15 always goes first. I have also seen the 5101 ram and EPROMs die from 12v down the 5v line, but surprisingly most things will live. I suspect when the first component goes short it consumes all the excessive voltage/current which saves other stuff.
Luckily your sound board will be saved in Paragon. Most games use 12v rail to power the amplifiers which would not be happy with HV coming in. On first generation sound boards, Bally used dirty noisy solenoid voltage which they regulate to 12v on the sound board for the amps.
As an update, I swapped in a working mpu from a Star Trek and the machine booted consistently.
I then swapped in the following components (u1, U2, u6, u7, u8) from the ST board into the Paragon board and had the same incomplete boot. The Paragon board typically got through the first blink and the first two LED flashes.
As the u15 is not socketed, I could not swap that in. I plan on swapping in the PIA's and seeing if there is any change.
What dmm do you have? can it read frequency?
If so check out the clock time at u9 p3 and u9 p37. Before replacing it. Use 7437 as u15*replacement.
In my xp U15 is what craps the bed when there is overvoltage on the 5v rail.
I don't think the fluke 77 iii meter reads a frequency, fluke 77 iv does frequency and capacitance. Do you have a logic probe with beep? Compare the sound of the beep on a good MPU to a bad MPU with the clock pulse.
Just hate to have you replace U15 and it was still good.
Mastech MS8268 is a good cheap meter that can read frequency. It is probably 1/4 the cost of the fluke 77 iii but has more features.
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