Re: need Bally MPU as-2518-35 advice

On Mar 27, 11:23 am, ArcRevival <arcaderevi...@xxxxxxxxx> wrote:
I have a Bally mpu that is locked up. No flicker, just stays on solid.
Here is what I have done so far:

1. removed battery, neutralized acid ( damage is pretty much contained
to edge of board and not up in component area). Metered traces that
looked like they could be damaged.Components in the "zone" look
untouched.

2. Checked +5 at TP5 and on pins outlined in pinrepair guide.
3. Checked Q1 Q2  Q5 and the diodes outlined in guide.
4. Jumpered pins 39 and 40 to see if it would flash ( it did not).
5. Metered from legs on pins at U6,U9 and U11 to solder side for
continuity.
6.Checked the following :
U9 pin 3 = 2.4 volts
U9 pin 36 = 2.6 volts
U9 pin 40 = 4.75 to 5.5 volts
U9 pin 5 = 2.8 volts

All were ok except I had  4.1 on U9 pin 5

7. Reseated all socketed chips.

I am thinking of ordering a corrosion zone kit( even though it seems
to be working per the guide) and replacing  U6,U9 and U11 next.  I do
not really want to invest in an Alltek just yet as I would rather
learn how to fix this. I might add this machine was HUO and does not
look like anyone ever worked on it so I am pretty sure jumpers etc are
correct and untouched.

Where is the best place to get the kit and chips if that is the
direction I should go.
Thanks
Dave

Make sure the jumpers are correct for the roms in it if this board
came to you dead. Does Pin 40 go low when the reset is triggered?

Next step would be to make sure U9, U11, U2, and U6 are working. Put
them in a different board to see if they boot up. You can swap the
two PIAs. Until you get the first flash pull the middle PIA and
5101. Make yourself a bench tester too. Find an old computer power
supply. It is much easier to fiddle with these boards when you do not
have to use the j4 connector inside a game. Can also rule out 5v,
12v, ground and 5v ripple issue from the filter cap.

Get new pias and cpu from arcadechips.com get new roms from
myhomegameroom.com
.

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