Re: black widow pcb problem no play no picture clock working

Disabling the watchdog circuit won't hurt anything. If you disable the
watchdog and the game comes up, then you know that the problem is only in
the watchdog circuitry. You might want to look at the Schematics and start
from the CPU (6502). Use your logic probe to check the Data and Address
lines, particularly at the address buffers (74LS244) which typically fail.
Make sure nothing is stuck high or low. Did you put the game in self test?
What does it do? I can't remember what you said in your first post.

My method of choice when I've tried the above, is use my signature analyzer.
It's easy to make a 6502 NOP fixture and I mapped out the signatures for
Black Widow from a working boardset. You just need a signature analyzer or
a cat box.

Matt

----- Original Message -----
From: "Daniel Piraino" <dpiraino@twcny.rr.com>
To: <vectorlist@vectorlist.org>
Sent: Friday, August 05, 2005 3:15 PM
Subject: Re: VECTOR: black widow pcb problem no play no picture clock
working

> Ok, nobody replied to that last one. I must have made it too confusing.
> Well Tony Jones told me to remove the CPU and check to see if the clock
> and the reset are working. I checked with the logic probe and I get
> pulsing from the clock. So I assume thats working. I checked the reset
> signal lines and their at a constant low state. There are lines from
> counters E4 and F4 that go to F7 (74LS14) that are marked POR(power on
> reset)on the schematic. Those lines are at a constant high state.
> Can anyone tell me what the reset should be doing?
> The only thing on this board that seems to be doing anything is the
> clock. Everthing else is either at a constant high or a constant low
> I am not familiar with how the watchdog works or the power on reset for
> that matter. I assume that the watchdog comes on whenever there is a
> problem on the board and stops anything else from being damaged (like
> the monitor).
> If I disable the watchdog, by putting the WDDIS test point to ground,
> will that hurt anything? Will it get the game running again so I can see
> whats going on?
> Or is that not the right direction to go in?
> I wish someone would put out an atari vector pcb repair and
> toubleshooting FAQ.
> I looked through the vector list archive and I have found nothing that
> could help me.
> I can stare at this schematic all day long and not make heads or tails
> of whats going on.
> I have no idea what test signals I should be getting with the logic probe.
> Well if someone could give me a little info I would appreciate it.
> I sure need it
> Dan Piraino
>
> Daniel Piraino wrote:
>
> > Checked clock and reset signal
> >
> > I removed the CPU
> >
> > I probed the clock and it is pulsing normally all the way up to pin 5
> > of E4 counter(74LS193).
> >
> > The POR is high when it exits pin 14 of E4 counter (74LS193) and pins
> > 2 and 12 of F4 counter (74LS393) and enters F7 (74LS14) at pins 4 and 5.
> >
> > But once it exits F7 (74LS14) at pin 3 and 6. It becomes low where it
> > goes out to R8 (TL082), E3 (74LS00), K3 (74LS74) and the POR test
> > point. It remains low from pin 4 of R8 (TL082) out to the reset.
> >
> > pin 3 of E3 (74LS00) goes out high to H4 counter (74LS393), as it
> > exits pins 6 and 13 of H4 counter (74LS393) it goes low out to K3
> > (74LS74) and F4 counter (74LS393).
> >
> > Pin 9 of L4 (74LS08) is high out to the WDDIS test point. Pins 8 and
> > 10 of L4 (74LS08) are low.
> >
> > Well I hope thats understandable. Its the only way for me to describe
> > whats happening,
> >
> > Hope someone can help
> > Thanks,
> > Dan Piraino
> >
> > -----Original Message-----
> > From: Daniel Piraino <dpiraino@twcny.rr.com>
> > To: vectorlist@vectorlist.org
> > Date: Tue, 02 Aug 2005 23:49:32 -0400
> > Subject: Re: VECTOR: black widow xy monitor problem
> >
> >>
> >> The reset tests low with the logic probe
> >> Thanks,
> >> Dan Piraino
> >>
> >> Daniel Piraino wrote:
> >>
> >> > The board set is not working
> >
> >
> > get the schematics from the web.
> > use the logic probe to check the clock and reset signal.
> > i know you said it is low, but check it from end-to-end.
> > if the clock seems dead from the begining then replace the crystal.
> >
> > once the clock and reset are good we can move forward.
> >
>
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> >
> >
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Received on Fri Aug 5 18:58:25 2005