The good, the bad and the ugly IC

[Guest]

Archived from groups: rec.games.video.arcade.collecting (More info?)

So I'm checking my moon cresta galaxian type frogger board to see why the
game resets when you enter the road. I test the ICs with the multimeter on
diode setting. Red to ground. I find like 15 different ICs that read short
and a couple that read open. The game seems like it is so close to running,
is it normal to have so many bad ICs? Will I really need to replace them
all? Lets see.... $6 worth of parts and 3 weeks of work. I think I will try
the piggyback method when I get the parts in but I wonder what difference it
would make if they all tested good. I know the game is 20+ years old.

Rick

 

[Guest]

Archived from groups: rec.games.video.arcade.collecting (More info?)

Rick,

Do a quick Google search in the NG on 'randy fromm diode test' and read
for a bit. Then decide if you want to hack your board.

- Craig


Pepelepew wrote:
> So I'm checking my moon cresta galaxian type frogger board to see why
the
> game resets when you enter the road. I test the ICs with the
multimeter on
> diode setting. Red to ground. I find like 15 different ICs that read
short
> and a couple that read open. The game seems like it is so close to
running,
> is it normal to have so many bad ICs? Will I really need to replace
them
> all? Lets see.... $6 worth of parts and 3 weeks of work. I think I
will try
> the piggyback method when I get the parts in but I wonder what
difference it
> would make if they all tested good. I know the game is 20+ years old.
>
> Rick

 

[Guest]

Archived from groups: rec.games.video.arcade.collecting (More info?)

Probably not that many unless you had a serious power surge on the
board. If the game is almost working chances are it's just one bad IC
or trace somewhere. Don't forget to double-check your supply voltages
on the card, and reseat all the socketed chips.

Piggy-backing might help you find that one chip that may be bad. To be
honest I haven't tried that myself, but it might work for you. I'd
recommend using an IC with an identical part number to eliminate any
differences in chip performance.

The Randy Fromm diode test has been somewhat of a hot button among some
on the NG (myself included). The only situation where it would work is
testing depletion mode FETs without a clamping diode. I've been told it
works well on pinball soleniod driver cards (which kinda makes sense),
but it really doesn't work any place else. Don't get me wrong, Randy's
contributions have been an asset to the NG, but that one particular
article I believe misses the mark.

- Craig




Pepelepew wrote:
> Ah yes, but I got it direct from the Randy video tapes. Wow, I found
you in
> one of those post, small world. These are soldered ICs and I do not
have an
> oscilloscope but I do have a logic probe......but have yet to learn
to use
> it. Is there a more definitive way to test these or is piggybacking
the
> replacement IC the best bet? and what if the diode test is
correct....what
> can a single output affect? I am sure that there is a culprit but I
would
> think it may be 4 or 5 not 15
>
> Rick
>
>
> "Craig Yarbrough" <hyarbr01@harris.com> wrote in message
> news:1113175135.636579.307480@o13g2000cwo.googlegroups.com...
> > Rick,
> >
> > Do a quick Google search in the NG on 'randy fromm diode test' and
read
> > for a bit. Then decide if you want to hack your board.
> >
> > - Craig
> >
> >
> > Pepelepew wrote:
> > > So I'm checking my moon cresta galaxian type frogger board to see
why
> > the
> > > game resets when you enter the road. I test the ICs with the
> > multimeter on
> > > diode setting. Red to ground. I find like 15 different ICs that
read
> > short
> > > and a couple that read open. The game seems like it is so close
to
> > running,
> > > is it normal to have so many bad ICs? Will I really need to
replace
> > them
> > > all? Lets see.... $6 worth of parts and 3 weeks of work. I think
I
> > will try
> > > the piggyback method when I get the parts in but I wonder what
> > difference it
> > > would make if they all tested good. I know the game is 20+ years
old.
> > >
> > > Rick
> >

 

[Guest]

Archived from groups: rec.games.video.arcade.collecting (More info?)

I don't think you understand the "diode test"....
Some pins are tied low or high on the board, and some are NC...
you need to be conscious of those things when doing your testing.
It is a useful test if you know the chip in question and its application,
but you shouldn't be blindly replacing chips if you don't understand
how things work.

Matt

P.S. Don't piggyback chips... that's just retarded.

"Pepelepew" <pepelepew9@worldnet.att.net> wrote in message news:7Nh6e.62606$cg1.56446@bgtnsc04-news.ops.worldnet.att.net...
> So I'm checking my moon cresta galaxian type frogger board to see why the
> game resets when you enter the road. I test the ICs with the multimeter on
> diode setting. Red to ground. I find like 15 different ICs that read short
> and a couple that read open. The game seems like it is so close to running,
> is it normal to have so many bad ICs? Will I really need to replace them
> all? Lets see.... $6 worth of parts and 3 weeks of work. I think I will try
> the piggyback method when I get the parts in but I wonder what difference it
> would make if they all tested good. I know the game is 20+ years old.
>
> Rick

 

[Guest]

Archived from groups: rec.games.video.arcade.collecting (More info?)

Piggybacking only occasionally seems to produce a result, and if it fixes
the problem, might help a bit. A logic comparator sometimes reveals the
problem because it is sort of like piggybacking, but it's XOR'd IIRC with
the chip and has high impedance into the inputs or other dark magic...

"Matt Osborn" <osborn@alum.mit.edu> wrote in message
news:k7j6e.2126$4v3.1135@trndny03...
>I don't think you understand the "diode test"....
> Some pins are tied low or high on the board, and some are NC...
> you need to be conscious of those things when doing your testing.
> It is a useful test if you know the chip in question and its application,
> but you shouldn't be blindly replacing chips if you don't understand
> how things work.
>
> Matt
>
> P.S. Don't piggyback chips... that's just retarded.
>
> "Pepelepew" <pepelepew9@worldnet.att.net> wrote in message
> news:7Nh6e.62606$cg1.56446@bgtnsc04-news.ops.worldnet.att.net...
>> So I'm checking my moon cresta galaxian type frogger board to see why the
>> game resets when you enter the road. I test the ICs with the multimeter
>> on
>> diode setting. Red to ground. I find like 15 different ICs that read
>> short
>> and a couple that read open. The game seems like it is so close to
>> running,
>> is it normal to have so many bad ICs? Will I really need to replace them
>> all? Lets see.... $6 worth of parts and 3 weeks of work. I think I will
>> try
>> the piggyback method when I get the parts in but I wonder what difference
>> it
>> would make if they all tested good. I know the game is 20+ years old.
>>
>> Rick
>
>

 

[Guest]

Archived from groups: rec.games.video.arcade.collecting (More info?)

Ah yes, but I got it direct from the Randy video tapes. Wow, I found you in
one of those post, small world. These are soldered ICs and I do not have an
oscilloscope but I do have a logic probe......but have yet to learn to use
it. Is there a more definitive way to test these or is piggybacking the
replacement IC the best bet? and what if the diode test is correct....what
can a single output affect? I am sure that there is a culprit but I would
think it may be 4 or 5 not 15

Rick


"Craig Yarbrough" <hyarbr01@harris.com> wrote in message
news:1113175135.636579.307480@o13g2000cwo.googlegroups.com...
> Rick,
>
> Do a quick Google search in the NG on 'randy fromm diode test' and read
> for a bit. Then decide if you want to hack your board.
>
> - Craig
>
>
> Pepelepew wrote:
> > So I'm checking my moon cresta galaxian type frogger board to see why
> the
> > game resets when you enter the road. I test the ICs with the
> multimeter on
> > diode setting. Red to ground. I find like 15 different ICs that read
> short
> > and a couple that read open. The game seems like it is so close to
> running,
> > is it normal to have so many bad ICs? Will I really need to replace
> them
> > all? Lets see.... $6 worth of parts and 3 weeks of work. I think I
> will try
> > the piggyback method when I get the parts in but I wonder what
> difference it
> > would make if they all tested good. I know the game is 20+ years old.
> >
> > Rick
>