New F2K problem MPU boots but no displays and won’t take credits

[Daniel Lejnieks]

Hi All,

I am now getting the seven requisite flashes on the MPU but the game doe not go into attract mode and I can’t get the test buttons to work. Does anyone have any ideas as to why this might happen? The displays are getting good voltages.

Dan L.

[John Robertson]

Post by Daniel Lejnieks
Hi All,
I am now getting the seven requisite flashes on the MPU but the game doe not go into attract mode and I can’t get the test buttons to work. Does anyone have any ideas as to why this might happen? The displays are getting good voltages.
Dan L.

Hi Dan,

Try waiting a while - like ten minutes. The game normally has to have
all three balls in the bottom trough with the three switches closed. If
it doesn't have that then it tries cycling the ball holder assembly on
the upper left to clear any balls that might be in there. If the ball
stacker solenoid isn't working or the eject kickers beside it (blown
playfield fuse) then it just sits there and waits. After about five or
ten minutes it gives up and goes into attract mode.

If it never (wait 1/2 hour or so) goes into attract mode then get back
to us!

John :-#)#

[seymour.shabow]

Post by John Robertson
Try waiting a while - like ten minutes. The game normally has to have
all three balls in the bottom trough with the three switches closed. If
it doesn't have that then it tries cycling the ball holder assembly on
the upper left to clear any balls that might be in there. If the ball
stacker solenoid isn't working or the eject kickers beside it (blown
playfield fuse) then it just sits there and waits. After about five or
ten minutes it gives up and goes into attract mode.

It doesn't take 10 minutes to run the walker sequence. It tries to run
it 7 times at bootup if it doesn't see all 3 balls in the trough, gives
up, and puts the displays up. 2 minutes, max.

The player displays should all be on with the HSTD when it's running the
walker code, the credit/match will be off while it's running it. IF the
displays are blank the hstd might not be set to displayable characters
(00-09)

[Daniel Lejnieks]

Post by John Robertson
Try waiting a while - like ten minutes. The game normally has to have
all three balls in the bottom trough with the three switches closed. If
it doesn't have that then it tries cycling the ball holder assembly on
the upper left to clear any balls that might be in there. If the ball
stacker solenoid isn't working or the eject kickers beside it (blown
playfield fuse) then it just sits there and waits. After about five or
ten minutes it gives up and goes into attract mode.

It doesn't take 10 minutes to run the walker sequence. It tries to run
it 7 times at bootup if it doesn't see all 3 balls in the trough, gives
up, and puts the displays up. 2 minutes, max.
The player displays should all be on with the HSTD when it's running the
walker code, the credit/match will be off while it's running it. IF the
displays are blank the hstd might not be set to displayable characters
(00-09)

Thank you for the help. Even when left running the displays do not come up. It does not go into attract either. This machine has gremlins.

Dan L

[John Robertson]

Post by Daniel Lejnieks

Post by John Robertson
Try waiting a while - like ten minutes. The game normally has to have
all three balls in the bottom trough with the three switches closed. If
it doesn't have that then it tries cycling the ball holder assembly on
the upper left to clear any balls that might be in there. If the ball
stacker solenoid isn't working or the eject kickers beside it (blown
playfield fuse) then it just sits there and waits. After about five or
ten minutes it gives up and goes into attract mode.

It doesn't take 10 minutes to run the walker sequence. It tries to run
it 7 times at bootup if it doesn't see all 3 balls in the trough, gives
up, and puts the displays up. 2 minutes, max.
The player displays should all be on with the HSTD when it's running the
walker code, the credit/match will be off while it's running it. IF the
displays are blank the hstd might not be set to displayable characters
(00-09)

Thank you for the help. Even when left running the displays do not come up. It does not go into attract either. This machine has gremlins.
Dan L

Do you have a logic probe? If you do then you want to check the output
(Pin 3) of the 555 timer chip (the only 8-pin chip on the board, bottom
right area). It should be pulsing and if off-frequency I seem to recall
this can stall the MPU final boot. The schematic shows a voltage at the
pin using a DC meter, it should be close to that - this would indicated
fast pulsing DC is perhaps close to required levels.

A scope is handy about now or a frequency counter.

John :-#)#

[Daniel Lejnieks]

Ok - before I waste everyone’s time further here the technique of leaving on a really long time may have helped. I am now only seeing six flashes after leaving it on for about 18 hours. Will exorcise this gremlin and get back to you.

Dan L

Gotta love 40 year old electronics

Post by John Robertson

Post by John Robertson
Try waiting a while - like ten minutes. The game normally has to have
all three balls in the bottom trough with the three switches closed. If
it doesn't have that then it tries cycling the ball holder assembly on
the upper left to clear any balls that might be in there. If the ball
stacker solenoid isn't working or the eject kickers beside it (blown
playfield fuse) then it just sits there and waits. After about five or
ten minutes it gives up and goes into attract mode.

It doesn't take 10 minutes to run the walker sequence. It tries to run
it 7 times at bootup if it doesn't see all 3 balls in the trough, gives
up, and puts the displays up. 2 minutes, max.
The player displays should all be on with the HSTD when it's running the
walker code, the credit/match will be off while it's running it. IF the
displays are blank the hstd might not be set to displayable characters
(00-09)

Thank you for the help. Even when left running the displays do not come up. It does not go into attract either. This machine has gremlins.
Dan L

Do you have a logic probe? If you do then you want to check the output
(Pin 3) of the 555 timer chip (the only 8-pin chip on the board, bottom
right area). It should be pulsing and if off-frequency I seem to recall
this can stall the MPU final boot. The schematic shows a voltage at the
pin using a DC meter, it should be close to that - this would indicated
fast pulsing DC is perhaps close to required levels.
A scope is handy about now or a frequency counter.
John :-#)#
--
(Please post followups or tech inquiries to the USENET newsgroup)
John's Jukes Ltd.
MOVED to #7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3
[phone] (Pinballs, Jukes, Video Games)
www.flippers.com
"Old pinballers never die, they just flip out."

[Daniel Lejnieks]

Ok - it was a loose fuse clip. I replaced it and got back up to 7 flashes. Pin 3 of the 555 timer appears stuck low. Thanks again John - will work that up next

Dan L.

Ok - before I waste everyone’s time further here the technique of leaving on a really long time may have helped. I am now only seeing six flashes after leaving it on for about 18 hours. Will exorcise this gremlin and get back to you.
Dan L
Gotta love 40 year old electronics

Post by John Robertson

Post by John Robertson
Try waiting a while - like ten minutes. The game normally has to have
all three balls in the bottom trough with the three switches closed. If
it doesn't have that then it tries cycling the ball holder assembly on
the upper left to clear any balls that might be in there. If the ball
stacker solenoid isn't working or the eject kickers beside it (blown
playfield fuse) then it just sits there and waits. After about five or
ten minutes it gives up and goes into attract mode.

It doesn't take 10 minutes to run the walker sequence. It tries to run
it 7 times at bootup if it doesn't see all 3 balls in the trough, gives
up, and puts the displays up. 2 minutes, max.
The player displays should all be on with the HSTD when it's running the
walker code, the credit/match will be off while it's running it. IF the
displays are blank the hstd might not be set to displayable characters
(00-09)

Thank you for the help. Even when left running the displays do not come up. It does not go into attract either. This machine has gremlins.
Dan L

Do you have a logic probe? If you do then you want to check the output
(Pin 3) of the 555 timer chip (the only 8-pin chip on the board, bottom
right area). It should be pulsing and if off-frequency I seem to recall
this can stall the MPU final boot. The schematic shows a voltage at the
pin using a DC meter, it should be close to that - this would indicated
fast pulsing DC is perhaps close to required levels.
A scope is handy about now or a frequency counter.
John :-#)#
--
(Please post followups or tech inquiries to the USENET newsgroup)
John's Jukes Ltd.
MOVED to #7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3
[phone] (Pinballs, Jukes, Video Games)
www.flippers.com
"Old pinballers never die, they just flip out."

[Daniel Lejnieks]

There are a lot of choices for 555 timer chips. Is there a speed I should be looking for? I am getting close here.

Dan L.

Ok - it was a loose fuse clip. I replaced it and got back up to 7 flashes. Pin 3 of the 555 timer appears stuck low. Thanks again John - will work that up next
Dan L.

Ok - before I waste everyone’s time further here the technique of leaving on a really long time may have helped. I am now only seeing six flashes after leaving it on for about 18 hours. Will exorcise this gremlin and get back to you.
Dan L
Gotta love 40 year old electronics

Post by John Robertson

Post by John Robertson
Try waiting a while - like ten minutes. The game normally has to have
all three balls in the bottom trough with the three switches closed. If
it doesn't have that then it tries cycling the ball holder assembly on
the upper left to clear any balls that might be in there. If the ball
stacker solenoid isn't working or the eject kickers beside it (blown
playfield fuse) then it just sits there and waits. After about five or
ten minutes it gives up and goes into attract mode.

It doesn't take 10 minutes to run the walker sequence. It tries to run
it 7 times at bootup if it doesn't see all 3 balls in the trough, gives
up, and puts the displays up. 2 minutes, max.
The player displays should all be on with the HSTD when it's running the
walker code, the credit/match will be off while it's running it. IF the
displays are blank the hstd might not be set to displayable characters
(00-09)

Thank you for the help. Even when left running the displays do not come up. It does not go into attract either. This machine has gremlins.
Dan L

Do you have a logic probe? If you do then you want to check the output
(Pin 3) of the 555 timer chip (the only 8-pin chip on the board, bottom
right area). It should be pulsing and if off-frequency I seem to recall
this can stall the MPU final boot. The schematic shows a voltage at the
pin using a DC meter, it should be close to that - this would indicated
fast pulsing DC is perhaps close to required levels.
A scope is handy about now or a frequency counter.
John :-#)#
--
(Please post followups or tech inquiries to the USENET newsgroup)
John's Jukes Ltd.
MOVED to #7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3
[phone] (Pinballs, Jukes, Video Games)
www.flippers.com
"Old pinballers never die, they just flip out."

[John Robertson]

Ne555 or LM555 is fine. They are a standard so almost anyone's should
work fine.

John :-#)#

Post by Daniel Lejnieks
There are a lot of choices for 555 timer chips. Is there a speed I should be looking for? I am getting close here.
Dan L.

Ok - it was a loose fuse clip. I replaced it and got back up to 7 flashes. Pin 3 of the 555 timer appears stuck low. Thanks again John - will work that up next
Dan L.

Ok - before I waste everyone’s time further here the technique of leaving on a really long time may have helped. I am now only seeing six flashes after leaving it on for about 18 hours. Will exorcise this gremlin and get back to you.
Dan L
Gotta love 40 year old electronics

Post by John Robertson

Post by John Robertson
Try waiting a while - like ten minutes. The game normally has to have
all three balls in the bottom trough with the three switches closed. If
it doesn't have that then it tries cycling the ball holder assembly on
the upper left to clear any balls that might be in there. If the ball
stacker solenoid isn't working or the eject kickers beside it (blown
playfield fuse) then it just sits there and waits. After about five or
ten minutes it gives up and goes into attract mode.

It doesn't take 10 minutes to run the walker sequence. It tries to run
it 7 times at bootup if it doesn't see all 3 balls in the trough, gives
up, and puts the displays up. 2 minutes, max.
The player displays should all be on with the HSTD when it's running the
walker code, the credit/match will be off while it's running it. IF the
displays are blank the hstd might not be set to displayable characters
(00-09)

Thank you for the help. Even when left running the displays do not come up. It does not go into attract either. This machine has gremlins.
Dan L

Do you have a logic probe? If you do then you want to check the output
(Pin 3) of the 555 timer chip (the only 8-pin chip on the board, bottom
right area). It should be pulsing and if off-frequency I seem to recall
this can stall the MPU final boot. The schematic shows a voltage at the
pin using a DC meter, it should be close to that - this would indicated
fast pulsing DC is perhaps close to required levels.
A scope is handy about now or a frequency counter.
John :-#)#
--
(Please post followups or tech inquiries to the USENET newsgroup)
John's Jukes Ltd.
MOVED to #7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3
[phone] (Pinballs, Jukes, Video Games)
www.flippers.com
"Old pinballers never die, they just flip out."

[Daniel Lejnieks]

Thank you - part is on order. Will let you know how it turns out.

Dan L.

Post by John Robertson
Ne555 or LM555 is fine. They are a standard so almost anyone's should
work fine.
John :-#)#

There are a lot of choices for 555 timer chips. Is there a speed I should be looking for? I am getting close here.
Dan L.

Ok - it was a loose fuse clip. I replaced it and got back up to 7 flashes. Pin 3 of the 555 timer appears stuck low. Thanks again John - will work that up next
Dan L.

Ok - before I waste everyone’s time further here the technique of leaving on a really long time may have helped. I am now only seeing six flashes after leaving it on for about 18 hours. Will exorcise this gremlin and get back to you.
Dan L
Gotta love 40 year old electronics

Post by John Robertson

Post by John Robertson
Try waiting a while - like ten minutes. The game normally has to have
all three balls in the bottom trough with the three switches closed. If
it doesn't have that then it tries cycling the ball holder assembly on
the upper left to clear any balls that might be in there. If the ball
stacker solenoid isn't working or the eject kickers beside it (blown
playfield fuse) then it just sits there and waits. After about five or
ten minutes it gives up and goes into attract mode.

It doesn't take 10 minutes to run the walker sequence. It tries to run
it 7 times at bootup if it doesn't see all 3 balls in the trough, gives
up, and puts the displays up. 2 minutes, max.
The player displays should all be on with the HSTD when it's running the
walker code, the credit/match will be off while it's running it. IF the
displays are blank the hstd might not be set to displayable characters
(00-09)

Thank you for the help. Even when left running the displays do not come up. It does not go into attract either. This machine has gremlins.
Dan L

Do you have a logic probe? If you do then you want to check the output
(Pin 3) of the 555 timer chip (the only 8-pin chip on the board, bottom
right area). It should be pulsing and if off-frequency I seem to recall
this can stall the MPU final boot. The schematic shows a voltage at the
pin using a DC meter, it should be close to that - this would indicated
fast pulsing DC is perhaps close to required levels.
A scope is handy about now or a frequency counter.
John :-#)#
--
(Please post followups or tech inquiries to the USENET newsgroup)
John's Jukes Ltd.
MOVED to #7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3
[phone] (Pinballs, Jukes, Video Games)
www.flippers.com
"Old pinballers never die, they just flip out."

--
(Please post followups or tech inquiries to the USENET newsgroup)
John's Jukes Ltd.
MOVED to #7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3
[phone] (Pinballs, Jukes, Video Games)
www.flippers.com
"Old pinballers never die, they just flip out."

[Daniel Lejnieks]

Thank you - part is on order. Will let you know how it turns out.
Dan L.

Post by John Robertson
Ne555 or LM555 is fine. They are a standard so almost anyone's should
work fine.
John :-#)#

There are a lot of choices for 555 timer chips. Is there a speed I should be looking for? I am getting close here.
Dan L.

Ok - it was a loose fuse clip. I replaced it and got back up to 7 flashes. Pin 3 of the 555 timer appears stuck low. Thanks again John - will work that up next
Dan L.

Ok - before I waste everyone’s time further here the technique of leaving on a really long time may have helped. I am now only seeing six flashes after leaving it on for about 18 hours. Will exorcise this gremlin and get back to you.
Dan L
Gotta love 40 year old electronics

Post by John Robertson

Post by John Robertson
Try waiting a while - like ten minutes. The game normally has to have
all three balls in the bottom trough with the three switches closed. If
it doesn't have that then it tries cycling the ball holder assembly on
the upper left to clear any balls that might be in there. If the ball
stacker solenoid isn't working or the eject kickers beside it (blown
playfield fuse) then it just sits there and waits. After about five or
ten minutes it gives up and goes into attract mode.

It doesn't take 10 minutes to run the walker sequence. It tries to run
it 7 times at bootup if it doesn't see all 3 balls in the trough, gives
up, and puts the displays up. 2 minutes, max.
The player displays should all be on with the HSTD when it's running the
walker code, the credit/match will be off while it's running it. IF the
displays are blank the hstd might not be set to displayable characters
(00-09)

Thank you for the help. Even when left running the displays do not come up. It does not go into attract either. This machine has gremlins.
Dan L

Do you have a logic probe? If you do then you want to check the output
(Pin 3) of the 555 timer chip (the only 8-pin chip on the board, bottom
right area). It should be pulsing and if off-frequency I seem to recall
this can stall the MPU final boot. The schematic shows a voltage at the
pin using a DC meter, it should be close to that - this would indicated
fast pulsing DC is perhaps close to required levels.
A scope is handy about now or a frequency counter.
John :-#)#
--
(Please post followups or tech inquiries to the USENET newsgroup)
John's Jukes Ltd.
MOVED to #7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3
[phone] (Pinballs, Jukes, Video Games)
www.flippers.com
"Old pinballers never die, they just flip out."

--
(Please post followups or tech inquiries to the USENET newsgroup)
John's Jukes Ltd.
MOVED to #7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3
[phone] (Pinballs, Jukes, Video Games)
www.flippers.com
"Old pinballers never die, they just flip out."

WOO HOO!!! Changed out the timer and the pin will now go into attract mode. There is no sound and no solenoids working other than the flippers but I do have working displays and can start the diagnosis these problems. Thank you to everyone who helped here. I'm sorry John - I think you did yourself out of a board repair this time :).

Dan L.

[John Robertson]

Post by Daniel Lejnieks

Thank you - part is on order. Will let you know how it turns out.
Dan L.

Post by John Robertson
Ne555 or LM555 is fine. They are a standard so almost anyone's should
work fine.
John :-#)#

There are a lot of choices for 555 timer chips. Is there a speed I should be looking for? I am getting close here.
Dan L.

Ok - it was a loose fuse clip. I replaced it and got back up to 7 flashes. Pin 3 of the 555 timer appears stuck low. Thanks again John - will work that up next
Dan L.

Ok - before I waste everyone’s time further here the technique of leaving on a really long time may have helped. I am now only seeing six flashes after leaving it on for about 18 hours. Will exorcise this gremlin and get back to you.
Dan L
Gotta love 40 year old electronics

Post by John Robertson

Post by John Robertson
Try waiting a while - like ten minutes. The game normally has to have
all three balls in the bottom trough with the three switches closed. If
it doesn't have that then it tries cycling the ball holder assembly on
the upper left to clear any balls that might be in there. If the ball
stacker solenoid isn't working or the eject kickers beside it (blown
playfield fuse) then it just sits there and waits. After about five or
ten minutes it gives up and goes into attract mode.

It doesn't take 10 minutes to run the walker sequence. It tries to run
it 7 times at bootup if it doesn't see all 3 balls in the trough, gives
up, and puts the displays up. 2 minutes, max.
The player displays should all be on with the HSTD when it's running the
walker code, the credit/match will be off while it's running it. IF the
displays are blank the hstd might not be set to displayable characters
(00-09)

Thank you for the help. Even when left running the displays do not come up. It does not go into attract either. This machine has gremlins.
Dan L

Do you have a logic probe? If you do then you want to check the output
(Pin 3) of the 555 timer chip (the only 8-pin chip on the board, bottom
right area). It should be pulsing and if off-frequency I seem to recall
this can stall the MPU final boot. The schematic shows a voltage at the
pin using a DC meter, it should be close to that - this would indicated
fast pulsing DC is perhaps close to required levels.
A scope is handy about now or a frequency counter.
John :-#)#

WOO HOO!!! Changed out the timer and the pin will now go into attract mode. There is no sound and no solenoids working other than the flippers but I do have working displays and can start the diagnosis these problems. Thank you to everyone who helped here. I'm sorry John - I think you did yourself out of a board repair this time :).
Dan L.

Ah, I'm backlogged about six months for board repairs, so happy to help!

If my advice was useful you could make a donation to Doctors Without
Borders.

John :-#)#

[Daniel Lejnieks]

Post by John Robertson

Thank you - part is on order. Will let you know how it turns out.
Dan L.

Post by John Robertson
Ne555 or LM555 is fine. They are a standard so almost anyone's should
work fine.
John :-#)#

There are a lot of choices for 555 timer chips. Is there a speed I should be looking for? I am getting close here.
Dan L.

Ok - it was a loose fuse clip. I replaced it and got back up to 7 flashes. Pin 3 of the 555 timer appears stuck low. Thanks again John - will work that up next
Dan L.

Ok - before I waste everyone’s time further here the technique of leaving on a really long time may have helped. I am now only seeing six flashes after leaving it on for about 18 hours. Will exorcise this gremlin and get back to you.
Dan L
Gotta love 40 year old electronics

Post by John Robertson

Post by John Robertson
Try waiting a while - like ten minutes. The game normally has to have
all three balls in the bottom trough with the three switches closed. If
it doesn't have that then it tries cycling the ball holder assembly on
the upper left to clear any balls that might be in there. If the ball
stacker solenoid isn't working or the eject kickers beside it (blown
playfield fuse) then it just sits there and waits. After about five or
ten minutes it gives up and goes into attract mode.

It doesn't take 10 minutes to run the walker sequence. It tries to run
it 7 times at bootup if it doesn't see all 3 balls in the trough, gives
up, and puts the displays up. 2 minutes, max.
The player displays should all be on with the HSTD when it's running the
walker code, the credit/match will be off while it's running it. IF the
displays are blank the hstd might not be set to displayable characters
(00-09)

Thank you for the help. Even when left running the displays do not come up. It does not go into attract either. This machine has gremlins.
Dan L

Do you have a logic probe? If you do then you want to check the output
(Pin 3) of the 555 timer chip (the only 8-pin chip on the board, bottom
right area). It should be pulsing and if off-frequency I seem to recall
this can stall the MPU final boot. The schematic shows a voltage at the
pin using a DC meter, it should be close to that - this would indicated
fast pulsing DC is perhaps close to required levels.
A scope is handy about now or a frequency counter.
John :-#)#

WOO HOO!!! Changed out the timer and the pin will now go into attract mode. There is no sound and no solenoids working other than the flippers but I do have working displays and can start the diagnosis these problems. Thank you to everyone who helped here. I'm sorry John - I think you did yourself out of a board repair this time :).
Dan L.

Ah, I'm backlogged about six months for board repairs, so happy to help!
If my advice was useful you could make a donation to Doctors Without
Borders.
John :-#)#
--
(Please post followups or tech inquiries to the USENET newsgroup)
John's Jukes Ltd.
MOVED to #7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3
[phone] (Pinballs, Jukes, Video Games)
www.flippers.com
"Old pinballers never die, they just flip out."

Done - I love Doctors Without Borders. Particularly right now with the vaccine distribution challenges. I was actually able to play a game on the machine but now I am back to 6 flashes. I am pretty sure the big sand resistor is bad - I get 50 volts when unplugged but when under load the voltage jumps to more than 70v. When I check the resistor it finally stabilizes somewhere around 4K ohms - should be 600 according to the schematics. Good fun!

Dan L.

[John Robertson]

Post by Daniel Lejnieks

Post by John Robertson

Thank you - part is on order. Will let you know how it turns out.
Dan L.

Post by John Robertson
Ne555 or LM555 is fine. They are a standard so almost anyone's should
work fine.
John :-#)#

There are a lot of choices for 555 timer chips. Is there a speed I

should be looking for? I am getting close here.

Post by Daniel Lejnieks

Post by John Robertson

Post by John Robertson

Dan L.

Ok - it was a loose fuse clip. I replaced it and got back up to 7

flashes. Pin 3 of the 555 timer appears stuck low. Thanks again John - will work that up next

Post by Daniel Lejnieks

Post by John Robertson

Post by John Robertson

Dan L.

Ok - before I waste everyone’s time further here the technique of leaving on a really long time may have helped. I am now only seeing six flashes after leaving it on for about 18 hours. Will exorcise this gremlin and get back to you.
Dan L
Gotta love 40 year old electronics

Post by John Robertson

Post by John Robertson
Try waiting a while - like ten minutes. The game normally has to have
all three balls in the bottom trough with the three switches closed. If
it doesn't have that then it tries cycling the ball holder assembly on
the upper left to clear any balls that might be in there. If the ball
stacker solenoid isn't working or the eject kickers beside it (blown
playfield fuse) then it just sits there and waits. After about five or
ten minutes it gives up and goes into attract mode.

It doesn't take 10 minutes to run the walker sequence. It tries to run
it 7 times at bootup if it doesn't see all 3 balls in the trough, gives
up, and puts the displays up. 2 minutes, max.
The player displays should all be on with the HSTD when it's running the
walker code, the credit/match will be off while it's running it. IF the
displays are blank the hstd might not be set to displayable characters
(00-09)

Thank you for the help. Even when left running the displays do

not come up. It does not go into attract either. This machine has gremlins.

Post by Daniel Lejnieks

Post by John Robertson

Post by John Robertson

Post by John Robertson

Dan L

Do you have a logic probe? If you do then you want to check the output
(Pin 3) of the 555 timer chip (the only 8-pin chip on the board, bottom
right area). It should be pulsing and if off-frequency I seem to recall
this can stall the MPU final boot. The schematic shows a voltage at the
pin using a DC meter, it should be close to that - this would indicated
fast pulsing DC is perhaps close to required levels.
A scope is handy about now or a frequency counter.
John :-#)#

WOO HOO!!! Changed out the timer and the pin will now go into attract

mode. There is no sound and no solenoids working other than the flippers but I do have working displays and can start the diagnosis these problems. Thank you to everyone who helped here. I'm sorry John - I think you did yourself out of a board repair this time :).

Post by Daniel Lejnieks

Post by John Robertson

Dan L.

Ah, I'm backlogged about six months for board repairs, so happy to help!
If my advice was useful you could make a donation to Doctors Without
Borders.
John :-#)#

Done - I love Doctors Without Borders. Particularly right now with the

vaccine distribution challenges. I was actually able to play a game on the machine but now I am back to 6 flashes. I am pretty sure the big sand resistor is bad - I get 50 volts when unplugged but when under load the voltage jumps to more than 70v. When I check the resistor it finally stabilizes somewhere around 4K ohms - should be 600 according to the schematics. Good fun!

Post by Daniel Lejnieks
Dan L.

I'm sure Doctors W/B will appreciate it!

As for the resistor, try lifting one end of it and see what its
resistance is then. 6 flashes is 43V problem, but it could be the MPU
zero-crossing circuit that has a problem or the 43V connection to the
MPU. Verify you have 43 (or more) at the TP when you are only getting 6
flashes.

John :-#)#

[Daniel Lejnieks]

Post by John Robertson

Thank you - part is on order. Will let you know how it turns out.
Dan L.

Post by John Robertson
Ne555 or LM555 is fine. They are a standard so almost anyone's should
work fine.
John :-#)#

There are a lot of choices for 555 timer chips. Is there a speed I

should be looking for? I am getting close here.

Post by John Robertson

Post by John Robertson

Dan L.

Ok - it was a loose fuse clip. I replaced it and got back up to 7

flashes. Pin 3 of the 555 timer appears stuck low. Thanks again John - will work that up next

Post by John Robertson

Post by John Robertson

Dan L.

Ok - before I waste everyone’s time further here the technique of leaving on a really long time may have helped. I am now only seeing six flashes after leaving it on for about 18 hours. Will exorcise this gremlin and get back to you.
Dan L
Gotta love 40 year old electronics

Post by John Robertson

Post by John Robertson
Try waiting a while - like ten minutes. The game normally has to have
all three balls in the bottom trough with the three switches

closed. If

Post by John Robertson

Post by John Robertson

Post by John Robertson

Post by John Robertson
it doesn't have that then it tries cycling the ball holder assembly on
the upper left to clear any balls that might be in there. If

the ball

Post by John Robertson

Post by John Robertson

Post by John Robertson

Post by John Robertson
stacker solenoid isn't working or the eject kickers beside it (blown
playfield fuse) then it just sits there and waits. After about five or
ten minutes it gives up and goes into attract mode.

It doesn't take 10 minutes to run the walker sequence. It tries to run
it 7 times at bootup if it doesn't see all 3 balls in the trough, gives
up, and puts the displays up. 2 minutes, max.
The player displays should all be on with the HSTD when it's running the
walker code, the credit/match will be off while it's running it. IF the
displays are blank the hstd might not be set to displayable characters
(00-09)

Thank you for the help. Even when left running the displays do

not come up. It does not go into attract either. This machine has gremlins.

Post by John Robertson

Post by John Robertson

Post by John Robertson

Dan L

Do you have a logic probe? If you do then you want to check the

output

Post by John Robertson

Post by John Robertson

Post by John Robertson
(Pin 3) of the 555 timer chip (the only 8-pin chip on the board, bottom
right area). It should be pulsing and if off-frequency I seem to recall
this can stall the MPU final boot. The schematic shows a voltage at the
pin using a DC meter, it should be close to that - this would indicated
fast pulsing DC is perhaps close to required levels.
A scope is handy about now or a frequency counter.
John :-#)#

WOO HOO!!! Changed out the timer and the pin will now go into attract

mode. There is no sound and no solenoids working other than the flippers but I do have working displays and can start the diagnosis these problems. Thank you to everyone who helped here. I'm sorry John - I think you did yourself out of a board repair this time :).

Post by John Robertson

Dan L.

Ah, I'm backlogged about six months for board repairs, so happy to help!
If my advice was useful you could make a donation to Doctors Without
Borders.
John :-#)#

Done - I love Doctors Without Borders. Particularly right now with the

vaccine distribution challenges. I was actually able to play a game on the machine but now I am back to 6 flashes. I am pretty sure the big sand resistor is bad - I get 50 volts when unplugged but when under load the voltage jumps to more than 70v. When I check the resistor it finally stabilizes somewhere around 4K ohms - should be 600 according to the schematics. Good fun!

Dan L.

I'm sure Doctors W/B will appreciate it!
As for the resistor, try lifting one end of it and see what its
resistance is then. 6 flashes is 43V problem, but it could be the MPU
zero-crossing circuit that has a problem or the 43V connection to the
MPU. Verify you have 43 (or more) at the TP when you are only getting 6
flashes.
John :-#)#
--
(Please post followups or tech inquiries to the USENET newsgroup)
John's Jukes Ltd.
MOVED to #7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3
[phone] (Pinballs, Jukes, Video Games)
www.flippers.com
"Old pinballers never die, they just flip out."

Wow - it is even worse when I lift a leg - the resistance reads 29 mega ohms. I have never had a failure like this before. With the power on but no load it gives me a nominal 50 v. Under minimal load the voltage jumps to 70v. I suspect it might go higher when a coil is on. I think this solves another problem which was frequent failure of the under play field fuse. It got hot when coils were activated until eventual failure. This is the first time I think I have had the voltage jump up under load. Am waiting on a new sand resistor

Dan L