Help identifying components on a 70's schematic

[gazz]

wondering if anyone can help with something thats been nugging me for a
while.

my pinball machine is supposed to have a tone board to produce the sounds
you get when hitting targets, it was built in 1976 so was one of the early
machines to use electronics in it, before that it was an electromechanical
chime unit (solenoids hitting xylophone plates)

the tone board is missing from my machine, but i have tracked down the
schematic, it's a copy from the service manual,
but it dosent show all component values, B1 and B2 are the mains ones i cant
figure out,

anyone able to have a look and maybe help me decide what those components
should be, and also if the others need changing to modern equivelents?

http://www.freewebs.com/ratsarsearcade/recel sound board.pdf if the
schematic scan,

It's a very basic circuit i assume, runs on 28 volts, triggered by a 28 volt
input on one of the 4 inputs to produce the relevent tone,
i've been told they were kinda like chimes in sound, and not the beep/boops
of bally machines of that era, but i've never heard on so dont know that for
sure,

Failing identifying the components, how hard would it be to make something
modern that would produce a nice chime like tone of a different frequancy
for each input? were talking dings and dongs here like a doorbell, but 4
different and seperate tones from a low dong to a high ding,

i'm not going to attempt this untill i have my other project sorted (the
change machine timer pulser module) just if i can identify the components i
can get them ordered same time i order the ones for the other project.

 

[Jamie]

wondering if anyone can help with something thats been nugging me for a
while.

my pinball machine is supposed to have a tone board to produce the
sounds you get when hitting targets, it was built in 1976 so was one of
the early machines to use electronics in it, before that it was an
electromechanical chime unit (solenoids hitting xylophone plates)

the tone board is missing from my machine, but i have tracked down the
schematic, it's a copy from the service manual,
but it dosent show all component values, B1 and B2 are the mains ones i
cant figure out,

anyone able to have a look and maybe help me decide what those
components should be, and also if the others need changing to modern
equivelents?

http://www.freewebs.com/ratsarsearcade/recel sound board.pdf if the
schematic scan,

It's a very basic circuit i assume, runs on 28 volts, triggered by a 28
volt input on one of the 4 inputs to produce the relevent tone,
i've been told they were kinda like chimes in sound, and not the
beep/boops of bally machines of that era, but i've never heard on so
dont know that for sure,

Failing identifying the components, how hard would it be to make
something modern that would produce a nice chime like tone of a
different frequancy for each input? were talking dings and dongs here
like a doorbell, but 4 different and seperate tones from a low dong to a
high ding,

i'm not going to attempt this untill i have my other project sorted (the
change machine timer pulser module) just if i can identify the
components i can get them ordered same time i order the ones for the
other project.

The A1 (Hex inverter) is a 7404 chip.
the B2 (quad 2 INPUT nor gate), chip is a 7402
B1 is a (dual 4 input nor gate), chip is a 7425
Those caps that aren't labeled. could be 1 uf each
electrolytic.
etc..

P.S.
This circuit can be replaced by something more modern and
fewer parts. But if you're trying to keep the originality of
the circuit, have fun.

http://webpages.charter.net/jamie_5"

 

[Andrew Holme]

wondering if anyone can help with something thats been nugging me for a
while.

my pinball machine is supposed to have a tone board to produce the sounds
you get when hitting targets, it was built in 1976 so was one of the early
machines to use electronics in it, before that it was an electromechanical
chime unit (solenoids hitting xylophone plates)

the tone board is missing from my machine, but i have tracked down the
schematic, it's a copy from the service manual,
but it dosent show all component values, B1 and B2 are the mains ones i
cant figure out,

anyone able to have a look and maybe help me decide what those components
should be, and also if the others need changing to modern equivelents?

http://www.freewebs.com/ratsarsearcade/recel sound board.pdf if the
schematic scan,

It's a very basic circuit i assume, runs on 28 volts, triggered by a 28
volt input on one of the 4 inputs to produce the relevent tone,
i've been told they were kinda like chimes in sound, and not the
beep/boops of bally machines of that era, but i've never heard on so dont
know that for sure,

Failing identifying the components, how hard would it be to make something
modern that would produce a nice chime like tone of a different frequancy
for each input? were talking dings and dongs here like a doorbell, but 4
different and seperate tones from a low dong to a high ding,

i'm not going to attempt this untill i have my other project sorted (the
change machine timer pulser module) just if i can identify the components
i can get them ordered same time i order the ones for the other project.

B1 is 7425
B2 is 7402

Oddly, B1 pin 3 is connected; but not pin 11; however, 7400 series TTL
inputs float high.

The circut could be simplified and power consumption reduced using modern
components.

For starters, I'd use a 3-terminal monolithic regulator
I'd use 74LS, 74HC or 4000-series logic
I might replace the TIP3055 with a MOSFET
I might use a push-pull output

 

[gazz]

Just as an aside, BTW, I'm a little annoyed that even though I took time
out of my life to design the pulser you asked for earlier, and came up
with something pretty nice, you seem to have rejected it out of hand
without ever having seen it, presumably for fear of compromising your
email address. What's up with that?

shit, sorry it came accross as that mate, i was waiting for it to turn up on
the usenet replayer, and it just has (says token timer in the bottom reight
corner)
i assumed your circuit was a 555 based one, hence i mentioned them in my
last post.

i was going to build both circuits when i get the breadboard and components,
i haddnt seen yours yet, but most definately had not dismissed it,

i really appreciate it, it looks pretty simple and does all i want,

so now i know what components i need, i'm going to get them ordered and
build it, getting some 555's as well as i want to play with them... be nice
to compare both compleated circuits, the 555 based one and the 40103 one.


i'm not fussed about my email addy really, i get tons of spam to it anyway,
just i seem to loose a few genuine emails too, so was waiting for the
schematic to be online rather than fart about having it sent to me, then it
not turning up and all that.
it's gazz AT kampenwagen DOT co DOT uk. by the way, but i regulary go over
my host servers disk space allowance, and loose mails, then when it goes
over the bandwith allowance i get nowt for the rest of the month... but at
least when that heppens they bounce the mails, over disk space it just
deletes them.

 

[gazz]

---
I doubt it.

First of all, the logic runs on +5V, which is supplied by the regulator
at the upper left-hand of the page.

Most common Zeners run with an Izt of 20 mA, which means that 20 mA
running through the 1.8k resistor will drop:


E = IR = 0.02A * 1800R = 36V.

That means that if the Zener is dropping 5.2V and the resistor is
dropping 36V then the input voltage must be in the vicinity of 42V
adding in the drop caused by the 1N4004.

That seems unlikely, so what I think is happening is that a 24V
transformer is being used to generate the DC, which will result in a
smoothed DC of about 34V.

Assuming a drop of about 0.5V across the MC140 and 33V on the left hand
side of the resistor (allowing 1V drop across the 1N4004) means that the
current through the resistor will be:

E 33V
I = --- = ------ = 0.15 ampere
R 220R

The resistor is rated for 6 watts, so, since:

P = IE = 33V * 0.15A = 4.95 watts

we're in the right ballpark, and with 33V into the 1.8k resistor and
5.2V on the cathode of the Zener we'll have about 28V across the
resistor, which will allow about:

E 33V
I = --- = ------- = 0.0183 amperes
R 1800R

through the Zener.

"About", because some of that will be shunted by the load, depending on
the Hfe of the transistor but, in any case, we're still in the right
ballpark.

Ahh right, think i just about understand that, the tone board is totaly
missing from my machine, just got the painted wire designations left on the
wooden base where it would have gone,

i've just been up and looked at the base board of the machine, heres what is
written where the tone board would go...

8 dots representing the inputs,
from left to right.... 0, 28, (under those two is written '28V AC') next 2
are speaker output, then D, A, C, B, and under them 'Sound'

The machine runs all it's coils, target contacts etc on 28 volts, (can
change the tap for the flippers and bumpers between 28, 30 or 32 volts)

the lights run on 7 volts AC,

it has a bridge rectifier in the machine, but that's used to run the
solenoid coils for the flippers and pop bumpers to make them quicker and
stronger than if they were run on AC apparantly.

this photo http://www.ipdb.org/showpic.pl?id=1405&picno=32281 may help a
little or may not, bottom left of the base, that's the sound board, i can
see some big (sand?) resisters, few largish capacitors, 3 ic's etc, also can
see only 3 inputs are used for the tones even though the board can make 4,
coresponds to the 3 input wires i have in my machine, 4th score tone is a
large gong bell.

Now let's take a look at the rest of the circuitry.

The two inverters of A1 are used to make a free-running astable
multivibrator which supplies clocks to A2, a 4 bit binary counter used
as a frequency divider.

Pin 12 will output a frequency half that of the clock input, pin 9 half
of that, pin 8 half of that, and pin 11 half of that.

These tones are gated by B2 and allowed to proceed into B1 and,
thereafter, into the audio amplifier, depending on the states of
SON A, B, C, and D.

Since the gates in B2 are NORs, the various SON inputs must be
quiescently high in order to block the various outputs of A2 and go low
when it's desired to allow that tone into the audio amp.

If TTL isn't pulled down it defaults high, so my guess would be that
instead of, as you state, 28V pulses are being used to gate the tones
through B2, the various SON inputs are pulled down to 0V to make that
happen.

excelent, sorry for just assuming it was positive inputs to trigger the
tones,

i've just taken some voltage readings on the wires, there's 30.1 volts AC
between the 28 and 0 volt input, connecting the negative lead of my
multimeter to the 0 volt wire, and the positive lead to one of the trigger
wires, hitting the relevent score target results in a 30.1 volt AC pulse on
that wire, it's the same on all 3 of the trigger wires, an AC pulse to
trigger the relevent tone.

that seems to throw a spanner in the works or does it, the +28 volts goes
to earth in the board, so could i have been reading a negative signal from
the input wires by using the black 0 volt wire to complete the circuit? or
have i just complicated thing even more by not doing the measurments right.

 

[Jasen Betts]

The A1 (Hex inverter) is a 7404 chip.
the B2 (quad 2 INPUT nor gate), chip is a 7402
B1 is a (dual 4 input nor gate), chip is a 7425
Those caps that aren't labeled. could be 1 uf each

only the main input reservoir cap is not not labeled and that size seems a little
small

Bye.
Jasen

 

[Rich Grise]

http://www.freewebs.com/ratsarsearcade/recel sound board.pdf if the
schematic scan,

This circuit doesn't have any provision for ringing - i.e., it will make
beeps and boops. You might be better off starting off from scratch - are
you any good with micros? Otherwise, you'd have to come up with some
damped oscillators.

Good Luck!
Rich

 

[gazz]

This circuit doesn't have any provision for ringing - i.e., it will make
beeps and boops. You might be better off starting off from scratch - are
you any good with micros? Otherwise, you'd have to come up with some
damped oscillators.

ahh right, cheers for that,

i might have a go at building the board just for the fun and experiance of
it, providing i can get all the parts,

im not really any good with much electronics stuff, can solder, make pcb's,
and make a circuit up from a diagram,
but never programmed any chips or owt like that, tho i am interested in
learning how to, as there are a few little projects that use pics that i'd
like to make.

would really like a ding dang dong sounding circuit, i could just track down
a set of electro mechanical chimes, but i like the idea of the electronic
sounds, not least because the volume can be adjusted for night time playing,

 

[Jasen Betts]

ahh right, cheers for that,

i might have a go at building the board just for the fun and experiance of
it, providing i can get all the parts,

im not really any good with much electronics stuff, can solder, make pcb's,
and make a circuit up from a diagram,
but never programmed any chips or owt like that, tho i am interested in
learning how to, as there are a few little projects that use pics that i'd
like to make.

would really like a ding dang dong sounding circuit, i could just track down
a set of electro mechanical chimes, but i like the idea of the electronic
sounds, not least because the volume can be adjusted for night time playing,

put RC low pass filters on the output of the binary counter so you get
4 triangle waves

swap the quad OR gate for a quad comparitor.
scale the voltages from the input capacitors so they peak at the
mid-point of the triangle wave and dip to just below the low point of
the triange wave.

replace the quad and gate with a quad comparitor.

It probably won't sound pretty but the volume will decrease sort-of
exponentially a bit like a gong.

simulating it in lt-spice it produces a wav sounds kind of like 'electric piano'

here's the asc. When run in ltspice it'll produce a file called pinball.wav
which you should be able to listen to by clicking it.

Version 4
SHEET 1 1588 680
WIRE 784 -416 768 -416
WIRE 800 -416 784 -416
WIRE 704 -400 640 -400
WIRE 704 -384 704 -400
WIRE 784 -384 784 -416
WIRE 784 -384 704 -384
WIRE 832 -384 784 -384
WIRE 640 -368 640 -400
WIRE 832 -320 832 -384
WIRE 704 -304 704 -384
WIRE 704 -304 688 -304
WIRE 640 -256 640 -288
WIRE 688 -224 688 -304
WIRE -672 -160 -1424 -160
WIRE 80 -160 -672 -160
WIRE 832 -160 832 -240
WIRE 832 -160 80 -160
WIRE 944 -160 832 -160
WIRE 1584 -160 944 -160
WIRE -1296 -96 -1376 -96
WIRE -1136 -96 -1216 -96
WIRE -944 -96 -1136 -96
WIRE -544 -96 -624 -96
WIRE -384 -96 -464 -96
WIRE -192 -96 -384 -96
WIRE 208 -64 128 -64
WIRE 368 -64 288 -64
WIRE 560 -64 368 -64
WIRE 960 -64 880 -64
WIRE 1120 -64 1040 -64
WIRE 1312 -64 1120 -64
WIRE -1376 -48 -1376 -96
WIRE -1136 -48 -1136 -96
WIRE -624 -48 -624 -96
WIRE -384 -48 -384 -96
WIRE 128 -16 128 -64
WIRE 368 -16 368 -64
WIRE 880 -16 880 -64
WIRE 1120 -16 1120 -64
WIRE -816 48 -832 48
WIRE -800 48 -816 48
WIRE -64 48 -80 48
WIRE -48 48 -64 48
WIRE -1376 64 -1376 32
WIRE -1136 64 -1136 16
WIRE -624 64 -624 32
WIRE -384 64 -384 16
WIRE 688 80 672 80
WIRE 704 80 688 80
WIRE 1440 80 1424 80
WIRE 1456 80 1440 80
WIRE -816 96 -816 48
WIRE -64 96 -64 48
WIRE 128 96 128 64
WIRE 368 96 368 48
WIRE 880 96 880 64
WIRE 1120 96 1120 48
WIRE -848 112 -912 112
WIRE -96 112 -160 112
WIRE -1296 128 -1312 128
WIRE -1136 128 -1136 112
WIRE -1136 128 -1216 128
WIRE -1008 128 -1136 128
WIRE -672 128 -672 -160
WIRE -672 128 -784 128
WIRE -544 128 -560 128
WIRE -384 128 -384 112
WIRE -384 128 -464 128
WIRE -256 128 -384 128
WIRE 80 128 80 -160
WIRE 80 128 -32 128
WIRE 688 128 688 80
WIRE 1440 128 1440 80
WIRE -944 144 -944 -96
WIRE -848 144 -944 144
WIRE -192 144 -192 -96
WIRE -96 144 -192 144
WIRE 656 144 592 144
WIRE 1408 144 1344 144
WIRE -1008 160 -1008 128
WIRE -256 160 -256 128
WIRE 208 160 192 160
WIRE 368 160 368 144
WIRE 368 160 288 160
WIRE 496 160 368 160
WIRE 832 160 832 -160
WIRE 832 160 720 160
WIRE 960 160 944 160
WIRE 1120 160 1120 144
WIRE 1120 160 1040 160
WIRE 1248 160 1120 160
WIRE 1584 160 1584 -160
WIRE 1584 160 1472 160
WIRE -1376 176 -1376 128
WIRE -1136 176 -1136 128
WIRE -624 176 -624 128
WIRE -384 176 -384 128
WIRE 560 176 560 -64
WIRE 656 176 560 176
WIRE 1312 176 1312 -64
WIRE 1408 176 1312 176
WIRE 496 192 496 160
WIRE 1248 192 1248 160
WIRE 128 208 128 160
WIRE 368 208 368 160
WIRE 880 208 880 160
WIRE 1120 208 1120 160
WIRE -1008 256 -1008 240
WIRE -912 256 -912 112
WIRE -912 256 -1008 256
WIRE -256 256 -256 240
WIRE -160 256 -160 112
WIRE -160 256 -256 256
WIRE 496 288 496 272
WIRE 592 288 592 144
WIRE 592 288 496 288
WIRE 1248 288 1248 272
WIRE 1344 288 1344 144
WIRE 1344 288 1248 288
WIRE -1008 432 -1008 336
WIRE -256 432 -256 336
WIRE 496 464 496 368
WIRE 1248 464 1248 368
WIRE -1136 560 -1136 240
WIRE -1008 560 -1008 512
WIRE -1008 560 -1136 560
WIRE -816 560 -816 160
WIRE -816 560 -1008 560
WIRE -384 560 -384 240
WIRE -256 560 -256 512
WIRE -256 560 -384 560
WIRE -64 560 -64 160
WIRE -64 560 -256 560
WIRE -1376 576 -1376 256
WIRE -1136 576 -1136 560
WIRE -624 576 -624 256
WIRE -384 576 -384 560
WIRE 368 592 368 272
WIRE 496 592 496 544
WIRE 496 592 368 592
WIRE 688 592 688 192
WIRE 688 592 496 592
WIRE 1120 592 1120 272
WIRE 1248 592 1248 544
WIRE 1248 592 1120 592
WIRE 1440 592 1440 192
WIRE 1440 592 1248 592
WIRE 128 608 128 288
WIRE 368 608 368 592
WIRE 880 608 880 288
WIRE 1120 608 1120 592
FLAG 128 96 0
FLAG 368 96 0
FLAG 128 608 0
FLAG 368 608 0
FLAG 640 -256 0
FLAG 784 -416 vcc
FLAG 688 80 vcc
FLAG 944 -160 OUT
FLAG -624 64 0
FLAG -384 64 0
FLAG -624 576 0
FLAG -384 576 0
FLAG -64 48 vcc
FLAG -1376 64 0
FLAG -1136 64 0
FLAG -1376 576 0
FLAG -1136 576 0
FLAG -816 48 vcc
FLAG 880 96 0
FLAG 1120 96 0
FLAG 880 608 0
FLAG 1120 608 0
FLAG 1440 80 vcc
SYMBOL Misc\\signal 128 -32 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V2
SYMATTR Value PULSE(0 5 0 0 0 .0005 .001)
SYMBOL res 304 -80 R90
WINDOW 0 0 56 VBottom 0
WINDOW 3 32 56 VTop 0
SYMATTR InstName R2
SYMATTR Value 860R
SYMBOL cap 352 -16 R0
SYMATTR InstName C1
SYMATTR Value 0.5µf
SYMBOL Misc\\signal 128 192 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V1
SYMATTR Value PULSE(0 5 1.2 0 0 .01 1K)
SYMBOL res 304 144 R90
WINDOW 0 0 56 VBottom 0
WINDOW 3 32 56 VTop 0
SYMATTR InstName R1
SYMATTR Value 300R
SYMBOL cap 352 208 R0
SYMATTR InstName C2
SYMATTR Value 2µf
SYMBOL diode 128 176 R270
WINDOW 0 32 32 VTop 0
WINDOW 3 0 32 VBottom 0
SYMATTR InstName D1
SYMBOL res 480 176 R0
SYMATTR InstName R3
SYMATTR Value 33K
SYMBOL res 480 272 R0
SYMATTR InstName R4
SYMATTR Value 10K
SYMBOL Comparators\\LTC1841 688 160 R0
SYMATTR InstName U1
SYMBOL Misc\\battery 640 -384 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V3
SYMATTR Value 5
SYMBOL res 816 -336 R0
SYMATTR InstName R5
SYMATTR Value 100K
SYMBOL Misc\\battery 496 448 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V8
SYMATTR Value 1.33v
SYMBOL Misc\\signal -624 -64 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V4
SYMATTR Value PULSE(0 5 0 0 0 .00025 .0005)
SYMBOL res -448 -112 R90
WINDOW 0 0 56 VBottom 0
WINDOW 3 32 56 VTop 0
SYMATTR InstName R6
SYMATTR Value 860R
SYMBOL cap -400 -48 R0
SYMATTR InstName C3
SYMATTR Value 0.25µf
SYMBOL Misc\\signal -624 160 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V5
SYMATTR Value PULSE(0 5 2.2 0 0 .01 1K)
SYMBOL res -448 112 R90
WINDOW 0 0 56 VBottom 0
WINDOW 3 32 56 VTop 0
SYMATTR InstName R7
SYMATTR Value 300R
SYMBOL cap -400 176 R0
SYMATTR InstName C4
SYMATTR Value 2µf
SYMBOL diode -624 144 R270
WINDOW 0 32 32 VTop 0
WINDOW 3 0 32 VBottom 0
SYMATTR InstName D2
SYMBOL res -272 144 R0
SYMATTR InstName R8
SYMATTR Value 33K
SYMBOL res -272 240 R0
SYMATTR InstName R9
SYMATTR Value 10K
SYMBOL Comparators\\LTC1841 -64 128 R0
SYMATTR InstName U2
SYMBOL Misc\\battery -256 416 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V6
SYMATTR Value 1.33v
SYMBOL Misc\\signal -1376 -64 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V7
SYMATTR Value PULSE(0 5 0 0 0 .000125 .00025)
SYMBOL res -1200 -112 R90
WINDOW 0 0 56 VBottom 0
WINDOW 3 32 56 VTop 0
SYMATTR InstName R10
SYMATTR Value 860R
SYMBOL cap -1152 -48 R0
SYMATTR InstName C5
SYMATTR Value 0.125µf
SYMBOL Misc\\signal -1376 160 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V9
SYMATTR Value PULSE(0 5 3.2 0 0 .01 1K)
SYMBOL res -1200 112 R90
WINDOW 0 0 56 VBottom 0
WINDOW 3 32 56 VTop 0
SYMATTR InstName R11
SYMATTR Value 300R
SYMBOL cap -1152 176 R0
SYMATTR InstName C6
SYMATTR Value 2µf
SYMBOL diode -1376 144 R270
WINDOW 0 32 32 VTop 0
WINDOW 3 0 32 VBottom 0
SYMATTR InstName D3
SYMBOL res -1024 144 R0
SYMATTR InstName R12
SYMATTR Value 33K
SYMBOL res -1024 240 R0
SYMATTR InstName R13
SYMATTR Value 10K
SYMBOL Comparators\\LTC1841 -816 128 R0
SYMATTR InstName U3
SYMBOL Misc\\battery -1008 416 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V10
SYMATTR Value 1.33v
SYMBOL Misc\\signal 880 -32 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V11
SYMATTR Value PULSE(0 5 0 0 0 .001 .002)
SYMBOL res 1056 -80 R90
WINDOW 0 0 56 VBottom 0
WINDOW 3 32 56 VTop 0
SYMATTR InstName R14
SYMATTR Value 860R
SYMBOL cap 1104 -16 R0
SYMATTR InstName C7
SYMATTR Value 1.0µf
SYMBOL Misc\\signal 880 192 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V12
SYMATTR Value PULSE(0 5 .2 0 0 .01 1K)
SYMBOL res 1056 144 R90
WINDOW 0 0 56 VBottom 0
WINDOW 3 32 56 VTop 0
SYMATTR InstName R15
SYMATTR Value 300R
SYMBOL cap 1104 208 R0
SYMATTR InstName C8
SYMATTR Value 2µf
SYMBOL diode 880 176 R270
WINDOW 0 32 32 VTop 0
WINDOW 3 0 32 VBottom 0
SYMATTR InstName D4
SYMBOL res 1232 176 R0
SYMATTR InstName R16
SYMATTR Value 33K
SYMBOL res 1232 272 R0
SYMATTR InstName R17
SYMATTR Value 10K
SYMBOL Comparators\\LTC1841 1440 160 R0
SYMATTR InstName U4
SYMBOL Misc\\battery 1248 448 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V13
SYMATTR Value 1.33v
TEXT 478 -336 Left 0 !.tran 4
TEXT 288 -296 Left 0 !.wave pinball.wav 16 44000 V(out)
TEXT 48 -384 Left 0 ;Pinball synthesizer

 

[gazz]

That appears to be the case since, according to the schematic, the black
wire isn't ground, as one would expect, it's 28VAC, and the red one is
ground.

Looking at what's connected to pin 1 with the euro "earth" signal should
make it clear.

Try this: With your multimeter set to 200VDC and its ground lead
connected to pin 1,

1. Measure the AC voltage on pin 2. What is it?

2. Measure the DC voltage on the cathode of the 1N4004. What is it?

3. Measure the voltage on the sound pins with no input connected to
them. What do you get?

4. Measure the voltage on the sound pins when you hit the score targets.
What do you get?

sorry for not getting the voltage readings yet, not feeling very well and
stuck in bed at the moment, not wise for me to be poking about in electrical
systems when i'm feeling like this.

will get the readings when i am well enough, but i cant get the number 2
reading, as i dont have any of the sound board at all, so no 1N4004 diode to
measure after.

 

[neon]

the two inverters generate a clock into a decade counter being gated extrnaly by a signal. YOU COULD replace and redesign all of it to make simple but why it should work as is. nothing wrong the way it is.