tech:phoenix
- Thread starter vernimark
- Start date
A
andrewhannay
Guest
RE: [ukvac] tech
hoenix
You're one of the lucky ones if you've got background music!
Anyway, long time since I repaired one of these.
But, if you've got no explosion or shot sounds then it sounds like it might
be a problem with your noise generation circuit.
This uses the same method as Space Invaders actually.
Check that there is a clock from IC42 pin 3 (555 timer), this goes into an
inverter (7414) at pin 11 (afraid I cannot see what IC number it is) then it
comes out of pin 12 of the same IC (inverted) and into the 4006 IC45?. There
should be a random bit stream at pin 1 of this IC. Also, there are a couple
of gates around the 4006 that you should check for signals, another 7414 (no
pin numbering or identification on the schematics) and what looks like IC12
(an XOR gate 74136).
This one signal that comes from the 4006 (present at pin 1) goes to both the
shot and explosion sound generation circuit so my guess is that there is no
random bit stream and in my experience it is ether the 555 timer (IC42) or
the hard to get hold of 4006 (IC45) that are not working.
Andrew
hoenix You're one of the lucky ones if you've got background music!
Anyway, long time since I repaired one of these.
But, if you've got no explosion or shot sounds then it sounds like it might
be a problem with your noise generation circuit.
This uses the same method as Space Invaders actually.
Check that there is a clock from IC42 pin 3 (555 timer), this goes into an
inverter (7414) at pin 11 (afraid I cannot see what IC number it is) then it
comes out of pin 12 of the same IC (inverted) and into the 4006 IC45?. There
should be a random bit stream at pin 1 of this IC. Also, there are a couple
of gates around the 4006 that you should check for signals, another 7414 (no
pin numbering or identification on the schematics) and what looks like IC12
(an XOR gate 74136).
This one signal that comes from the 4006 (present at pin 1) goes to both the
shot and explosion sound generation circuit so my guess is that there is no
random bit stream and in my experience it is ether the 555 timer (IC42) or
the hard to get hold of 4006 (IC45) that are not working.
Andrew
G
Guests
Guest
[ukvac] Re: techhoenix
Hi,
You need to look at the schematics... The noise generator part is a
4006 (at the bottom right of the first page), so you need to poke
this with a logic probe and then work forward or backwards, to see if
it is being triggered (via a 555 and an invertor) and is generating
noise. Both the shot and the explosion share some circuitry.
Regards, Colin
hoenixHi,
You need to look at the schematics... The noise generator part is a
4006 (at the bottom right of the first page), so you need to poke
this with a logic probe and then work forward or backwards, to see if
it is being triggered (via a 555 and an invertor) and is generating
noise. Both the shot and the explosion share some circuitry.
Regards, Colin
[ukvac] Re: techhoenix
Phoenix troubleshooting found in rgvac a long time ago:
-----
BOARD NO: 0077
GAME: Phoenix
MANUFACTURER: Taito
DATE: 1980
HARNESS: CENTURI-A
SYMPTOM (08/06/96)
-------
No ship explosion or shoot sound. Other sounds O.K.
SOLUTION
--------
IC5 and IC6 (LS374) are the sound control latches. Using a logic probe to
map
out which circuit contributes to what sounds gave the following results:-
IC5 (Data outputs)
pin 19 -> Barrier tone (Bit 0)
pin 2 -> Barrier tone (Bit 1)
pin 16 -> Barrier tone (Bit 2)
pin 5 -> Barrier tone (Bit 3)
pin 15 -> Alien hit explosion
pin 6 -> Bird wow-wow
pin 12 -> Music select
pin 9 -> Music on
IC6 (Data outputs)
pin 19 -> Alien swoop/hit tone (Bit 0)
pin 2 -> Alien swoop/hit tone (Bit 1)
pin 16 -> Alien swoop/hit tone (Bit 2)
pin 5 -> Alien swoop/hit tone (Bit 3)
pin 15 -> Alien hit explosion
pin 6 -> Alien swoop
pin 12 -> Ship fire
pin 9 -> Ship explosion
Both the ship fire and explosion circuits were fed from a linear feedback
shift register (IC46, CMOS 4006) that was in turn clocked from a NE555
oscillator (IC42). The oscilator was switched by TR1. Using a logic probe
verified that TR1 was working correctly and pin 3 of IC42 was oscillating as
was pin 3 of IC46. The outputs of IC46 taken at pins 8 and 9 were stuck
high.
These two outputs feed a an XOR gate (IC22, LS136) the output of which is
inverted and fed back into pin 1 of IC46. The schematic for this circuit
seemed to suggest that it was possible for this LFSR to "lock-up" if all the
shift register latches end up all-one, and using a pulse injector on pin 1
of
IC46 to add a few zeros into the LFSR chain started the sounds off and the
LFSR maintained itself from then on. Power cycling the board always seemed
to
result in the LSFR locking up. Since this seemed to be a "design fault"
rather
than a circuit fault, I examined some of the other LPN Phoenix board sets
and
these had a modification on them to insert zeros into the LFSR at power on
as
follows:-
Wire link: IC9 (8085) pin 3 -> IC28 (74LS05) pin 5
Wire link: IC28 (74LS05) pin 6 -> IC29 (74LS05) pin 9
It looks as if this was a "field" modification and it isn't a particularly
"neat" solution but it does seem to work.
hoenix Phoenix troubleshooting found in rgvac a long time ago:
-----
BOARD NO: 0077
GAME: Phoenix
MANUFACTURER: Taito
DATE: 1980
HARNESS: CENTURI-A
SYMPTOM (08/06/96)
-------
No ship explosion or shoot sound. Other sounds O.K.
SOLUTION
--------
IC5 and IC6 (LS374) are the sound control latches. Using a logic probe to
map
out which circuit contributes to what sounds gave the following results:-
IC5 (Data outputs)
pin 19 -> Barrier tone (Bit 0)
pin 2 -> Barrier tone (Bit 1)
pin 16 -> Barrier tone (Bit 2)
pin 5 -> Barrier tone (Bit 3)
pin 15 -> Alien hit explosion
pin 6 -> Bird wow-wow
pin 12 -> Music select
pin 9 -> Music on
IC6 (Data outputs)
pin 19 -> Alien swoop/hit tone (Bit 0)
pin 2 -> Alien swoop/hit tone (Bit 1)
pin 16 -> Alien swoop/hit tone (Bit 2)
pin 5 -> Alien swoop/hit tone (Bit 3)
pin 15 -> Alien hit explosion
pin 6 -> Alien swoop
pin 12 -> Ship fire
pin 9 -> Ship explosion
Both the ship fire and explosion circuits were fed from a linear feedback
shift register (IC46, CMOS 4006) that was in turn clocked from a NE555
oscillator (IC42). The oscilator was switched by TR1. Using a logic probe
verified that TR1 was working correctly and pin 3 of IC42 was oscillating as
was pin 3 of IC46. The outputs of IC46 taken at pins 8 and 9 were stuck
high.
These two outputs feed a an XOR gate (IC22, LS136) the output of which is
inverted and fed back into pin 1 of IC46. The schematic for this circuit
seemed to suggest that it was possible for this LFSR to "lock-up" if all the
shift register latches end up all-one, and using a pulse injector on pin 1
of
IC46 to add a few zeros into the LFSR chain started the sounds off and the
LFSR maintained itself from then on. Power cycling the board always seemed
to
result in the LSFR locking up. Since this seemed to be a "design fault"
rather
than a circuit fault, I examined some of the other LPN Phoenix board sets
and
these had a modification on them to insert zeros into the LFSR at power on
as
follows:-
Wire link: IC9 (8085) pin 3 -> IC28 (74LS05) pin 5
Wire link: IC28 (74LS05) pin 6 -> IC29 (74LS05) pin 9
It looks as if this was a "field" modification and it isn't a particularly
"neat" solution but it does seem to work.
A
andrewhannay
Guest
RE: [ukvac] techhoenix
NICE!
Hence your keen-ness to get the other sounds working again.
How much did you pay if it's not too rude to ask?????
Andrew
hoenix NICE!
Hence your keen-ness to get the other sounds working again.
How much did you pay if it's not too rude to ask?????
Andrew
A
andrewhannay
Guest
RE: [ukvac] techhoenix
That doesn't sound too expensive but I guess being Yanks they charged you
$30 shipping!
Anyway have you fixed your board yet?
Andrew
hoenix That doesn't sound too expensive but I guess being Yanks they charged you
$30 shipping!
Anyway have you fixed your board yet?
Andrew