TECH: Stern MPU-100 won't boot. Low voltage at U11 ?

[Guest]

Archived from groups: rec.games.pinball (More info?)

I have a Stern MPU-100 board that I cannot get to the initial flash
on the test bench. I rebuilt the reset section, and the board booted
fine, I replaced the ROM chips and sockets with another games, and the
board won't boot or get the initial flash. I double checked my work,
installed a NEW CPU at U9, U10 & U11 PIA, U8 5101, U15 74LS37.

I have 5.25vdc at U6,U2, U9,& U7, but at pin 40 on U11 I only get
4.74vdc and a pulse with my logic probe. Can this slightly lower
voltage be a sign of trouble? I got this voltage with both the old &
new chips, same socket, & it previously worked.

I am trying to eliminate sources of trouble, & this is one of my
suspects. Anything else to look for? I have tried all the advice on the
Marvin guides but nithing seems to be wrong.

Jumpers SHOULD be OK, as I haven't changed them and am using 2716
chips.

 

[Guest]

Archived from groups: rec.games.pinball (More info?)

You can get the first flicker out of the board with just U6 installed for
ROM chips, and no U7, U8, U10 or U11 installed. I'd probably start with this
"bare bones" setup to have only the minimal components on the board to get
the initial flicker- eliminate anything unneeded to narrow the scope of
things you have to look at or suspect.

If you still don't get a flicker at powerup this way, then best bet is
you've got the board jumpered wrong for the type of ROM chip(s) you have
installed- check jumper settings against the type of chips you're trying to
use- we have jumper settings posted on our website at: www.actionpinball.com
in the Technical Articles section.

> Jumpers SHOULD be OK, as I haven't changed them and am using 2716
> chips.

"Should", "maybe", "might", and "looks good" often doesn't cut it. What
were the old chips? Or more exactly, what was the board originally set up
for before you installed 2716 chips? Most MPU-100 games used 9316A masked
prom chips from the factory which have a different pinout from 2716 EPROMs,
and you need to not only change some jumpers to go to 2716 EPROMs, but make
a couple of physical modifications to the board too, in order to use 2716's
on it.

Lack of the 1st flicker at powerup indicates that the CPU cannot access
startup data in the U6 rom chip and execute it. U6 contains the startup
program. If you get 1st flicker, this means the CPU found the code in U6,
and started executing it.

You won't get a 1st actual flash after the flicker if only U6 is installed-
you need to have the rest of the ROM chips installed and board set up right
for the types of chips they are, in order to get the 1st flash, and beyond.

Worth checking.

Hope that helps!

Ray J.
--
Action Pinball & Amusement, LLC
Salt Lake City, Utah USA
Web: www.actionpinball.com

We're serious about pinball. Anything else is just for fun!



<kul4skool1@hotmail.com> wrote in message
news:1122745162.721351.36730@g49g2000cwa.googlegroups.com...
> I have a Stern MPU-100 board that I cannot get to the initial flash
> on the test bench. I rebuilt the reset section, and the board booted
> fine, I replaced the ROM chips and sockets with another games, and the
> board won't boot or get the initial flash. I double checked my work,
> installed a NEW CPU at U9, U10 & U11 PIA, U8 5101, U15 74LS37.
>
> I have 5.25vdc at U6,U2, U9,& U7, but at pin 40 on U11 I only get
> 4.74vdc and a pulse with my logic probe. Can this slightly lower
> voltage be a sign of trouble? I got this voltage with both the old &
> new chips, same socket, & it previously worked.
>
> I am trying to eliminate sources of trouble, & this is one of my
> suspects. Anything else to look for? I have tried all the advice on the
> Marvin guides but nithing seems to be wrong.
>
> Jumpers SHOULD be OK, as I haven't changed them and am using 2716
> chips.
>

 

[Guest]

Archived from groups: rec.games.pinball (More info?)

Oooops *RAY* said, not me. Usually I'm confused with Clay, now I'm
REALLY honored to be mistaken for Ray!
--
Cliffy - CARGPB2
A passion for pinball!
http://www.passionforpinball.com

 

[Guest]

Archived from groups: rec.games.pinball (More info?)

As Cliffy said this board did not "normally" take 2716 chips it used 9316
Masked ROM from the
factory. I put out a mod back in the early 90's that allows you to use a
single 2732 EPROM in U6
that replaces U2 and U6 on that board. If you have the capability to
program a 2732 you can modify the board
to use a single 2732 at U6 with the combined U2 and U6 images.

Should you need that mod; it can be found on my homepage under Favorite
links see Bally_MPU_Jumpers.txt
Note it is just a text file, no pics; the mod is fairly straightforward.

Regards,
Dallas...
Home Page: www.geocities.com/d_overturf
Replies regarding News Group messages to me may get a challenge verifier
back. (CHAP).
The Sender may be >
Subject: [Challenge Response] Confirm your email by visiting this URL
https://smtp.stowetel.com/challenge/... SomeURL.
If so you need to Click on the link in the challenge and do what it says.
This is usually a one time deal.
---------------------------------------------------------------------------------------------------------------------------


<kul4skool1@hotmail.com> wrote in message
news:1122745162.721351.36730@g49g2000cwa.googlegroups.com...
> I have a Stern MPU-100 board that I cannot get to the initial flash
> on the test bench. I rebuilt the reset section, and the board booted
> fine, I replaced the ROM chips and sockets with another games, and the
> board won't boot or get the initial flash. I double checked my work,
> installed a NEW CPU at U9, U10 & U11 PIA, U8 5101, U15 74LS37.
>
> I have 5.25vdc at U6,U2, U9,& U7, but at pin 40 on U11 I only get
> 4.74vdc and a pulse with my logic probe. Can this slightly lower
> voltage be a sign of trouble? I got this voltage with both the old &
> new chips, same socket, & it previously worked.
>
> I am trying to eliminate sources of trouble, & this is one of my
> suspects. Anything else to look for? I have tried all the advice on the
> Marvin guides but nithing seems to be wrong.
>
> Jumpers SHOULD be OK, as I haven't changed them and am using 2716
> chips.
>

 

[Guest]

Archived from groups: rec.games.pinball (More info?)

Many thanks to Ray Johnson and John Wart for helping me diagnose this
problem. The board was not jumpered for 2716 ROMs, as it had masked
ones on it. I jumpered as per the Marvin guides, and she boots ! Once
again, RGP comes to my rescue .

I will investigate your site, Dallas.