Leon Borre Bally -61 Squawk and Talk Sound Repair

Bally "Squawk and Talk" sound board AS-2518-61

This is the most elaborated sound board in the Bally pinball's of the 80's. We can connect an extra " vocaliser" board , to extend the number of sound and phrases.

The board has a self test at power-up. On the board is a led , that will flash a number of times (5) to indicate wich elements are ok ( or not ok ) .ATTENTION; a brief flicker can occur at start up, this counts NOT as a flash.

The first flash means the memory is ok. That can be the internal memory portion of the cpu ( 6802) or the external memory chip ( 6810).

The second flash means the PIA at U7 is ok.

The third flash means the second PIA at U11 is ok.

The fourth flash means that the sound generator AY-3-8912 is ok

The fifth flash means the speech decoder TMS 5200 is ok.

Why use an extra test program if there is a self test? Well the self test indicates something is wrong but brings no solution ( just replacement) The outputs of the PIA's are not tested.The most simple fault will stop the self test from running at all, where this extra test will run without there is a PIA or a memory on the board, it still will perform the test ..!! We work also around bad sound roms,at the beginning of the test. We could test the PIA's and the memory chip by plugging these in the CPU board, this is a partial solution, but brings no answers if there is something wrong in a socket , a short between run's or an address or databus pulled low or high permanetly by another faulty element so whe choose for the extra test anyway. Let's look at the practical side of things..

A very good explanation by Clive Jones about this board here .......

The test program wil test first the CPU and circuitery the PIA's and the memory. The memory can be an external memory type 6810 if we use a 6808 as CPU chip. In case we have a 6802 CPU the external memory is not needed , because the 6802 has a portion of internal ram that will be used instead. If these initial test are done , we test the amplifier chip in a simple way, and then let the self test take over to determine the status of the sound generator and the speech decoder.

The squalk and talk board

Place the test eprom in the socket of soundrom U5. When tensions are applyed the test will run immediatly,if ok the connected control led will blink. If so you can measure the outputs of both PIA chips ( U7 and U11) Pins 2 to 17 19 all will "dance" up and down between 0 and 5volts. To start the memory test push the button on the soundboard , the control led will stop for a brief moment and then continou blinking. If the memory test fails , the led will stay steady "on" or "off", but testing continuos in an endless loop, this allow us to measure the arriving signals on the memory chip..

Start.

All we need is a 12 volts supply ,a -5 volt supply, a loudspeaker and the test eprom . Find the test eprom image here ... (2716) and here (2532) . I put both images here because boards are equipped with one of these type roms.

How about that. Well on the board are a lot of jumpers , we do not change these but use a type of eprom that suits the board, the jumpers used to change or adapt for a 2716 or a 2532 are listed here ... these are the ones we will not change, the others and their functions;

L = you have a 6808 processor and a 6810 memory cgip on board.

K = You have a 6802 processor and no extra memory chip on board.

H = No vocaliser board .

J = With vocaliser board attached.

EE = No AY-3-8912 sound generator

For the test purposes always, N and DD jumpers present, and no CC or M jumper. This allows us to change the volume with the potentiometers on the board. ( most common setting)

Connections.

To excecute the first test only connect:

12 volts at J1, pin 17= 12 pin 16 = ground .

Make a connection between C14 and C15 both - sides .

Connect the control led at pin 15 of the cpu chip U1 and ground.

Bottom in the middle the 12 at pin 17and 16 of J1. The control led between pin15 U1 and ground, and a temporally connection between C14 and C15 negative sides= ground

Control led

The control led is a normal led in serie with a 470ohm resistor, and used in many appliqations of this site , to make one look at the page ," Repair of Bally/Stern CPU boards." here the photo ..

Control led.

Practical

When tension is applyed the test starts immediatly, the control led starts blinking. We can check the outputs of both PIA's U7 and U11, their pins 2 to 17 19 will go up and down between 0 and 5 volts. Is this not the case then we look at some basic signals at the cpu U1, to find out why.On pins 2,3,4 and 40 we must find 5 volts, and clock signals at pins 37 and 39 at 37 the signal is strong 2,5 volts and at pin 39 1,5 volts , when these tensions are ok and the clocks present the cpu should start, if not remove the test eprom , the memory chip U6, both PIA's U7 nand U11, the TMS5200 and the other soundroms U2,U3,and U4. Now look again if the cpu works , look if there are signals at the addressbus pins 9 to 25 ( except pin 21 = ground) find signals between 0,5 and 2 volts, the same on the databus pins 26 to 33. two possibilities, signals are there =CPU ok , no signals , replace the CPU.

No we have the case of a CPU that runs fine in stand-alone and with the test eprom in place the test wont' work = the control led does not blink...

We remove again the test eprom and look at the signals arriving on his socket.The different data and address signals are there? If not bad contact in the socket, look at the selection signals , we need a 0,5 volt signal at pin 19 and a 4,5 volt signal at pin 20.Use a universal voltmeter, a digital test lamp or a scope to control these tensions and signals.Is there a missing signal look at the schematic to see where it comes from , suspect always sockets, if it is a address or databus signal that is missing , bend up the pin of the CPU where it comes from , if now the bend up pin delivers the signal that means you have a short on that address or data line. You have to look that up.. Normally you did find the fault . Place back the test eprom first , afther the test works ( control led blinks) place back the other chips, the test must stay working afther these are putted back, otherwise one of the chips is bad...now start controlling the PIA outputs.These will " dance" up and down from 0 to 5 volts .If some are missing the PIA is bad , if all are missing check again the socket connections ,all the signals to the PIA included the selection signals are data or addressbus signals , as these where already checked we have to find at the pins of the PIA's the same results , check as extra the pins 21 ( 4,5 volts using a 2532, 0 volts using a 2716 ) pin 23 , 4 volts , pin 25 2,5 volts , if missing some of these take out the schematic and look where the signal comes from , there must be a cut or a bad element ( easy) If the signals are all present , and still no outputs the PIA is bad. At this point you must have found the fault.

Memory test

We start the memory test by the pushbutton on the board, the control led will stop blinking , and restart blinking afther about two seconds if all is ok. Not ok the control led will stay in his current position , that can be a steady on or off. Anyway the test continous checking the memory and allow us to measure the arriving signals at the memory chip U6. On pins 1,14 and 15 we find ground on pin 24 5 volts. All other pins receive signals between 1,5 and 3 volts. If that is ok, and the test indicate a bad memory, you can be shure the chip is bad. Otherwise agian suspect the socket.At this point you must have found the fault in the board.

Amplifier, sound generator, speech processor chip's

To start we connect the -5 volts and the loudspeaker. The loudspeaker at pin 1 2 of J2, the -5 volts at TP4. We can disconnect the control led.

Still the 12volts on pin 17 and 16 of J1, and the connection between C14 and C15. On top the -5volts arriving at TP4 ( black wire) and the loudspeaker connected at J2 pins 1 and 2. To provide the 12 and the -5 volts use an power supply of a PC.

To test the amplifier , we inject some noise by putting our finger on different capacitors connecting the stages of the amplifier chain. Starting with C25, touching here will induce a loud humming sound , if not the TDA2002 U18 is bad. Mounting a next stage touch C24 if no humming IC14 is bad, , next is C19 if no humming here U13 is bad Another stage is C36 no humming again U14 tested now via another chanel, and last one C35 another channel to test U13. If the amplifier stages are ok, we put all the original sound roms in place and launch the board again. Look at the 'on board' led; it should flash 5 times; The first three are for shure as they test the memory and the both PIA's who are certainly ok at this point. the 4the flash tell us the soundgenerator AY-3-8912 is ok and the last 5the flash that the speech processor TMS5200 is good. If the 4th or 5th flash is missing the sound generator or speech processor are to replace. If ok push the button to launch all sounds of the board. When ever you have no flashes at all , replace the sound roms..,

Last possibility's

If the board works ok on the bench and not in the machine, measure first if you have -5 volts at TP4. The -5 volts now is made from the 6,3AC voltage arriving at pins 7 and 10 of J1. Input at the 7905 stabilisator should be about -11 volts , if not replace the diode and de both capacitors, if ok and no output the 7905 is bad. Look also at the connections and the loudspeaker of the machine.