Leon Borre Zaccaria 1B1125 Sound Board Repair

Zaccaria sound board type 1B1125 repair.

The first Zaccaria generation pinball's had very simple sound boards , some had no sound board at all and only a simple signal generator is placed on the driver board , the repair of this signal generator is explaned on the page that threats the repair of the driver board type 1B1110 on this site. The 1B1125 sound board is mounted like a display without the glass, and connected to the same ribbon cable that goes to all display's. The test here described will test all active components of this sound board

Here a photo of the 1B1125 sound board

What we need to repair this board on the bench is , a loudspeaker, a 5 volts source, and two cables that fit into CN1 and CN2 to connect the board , and a external pulse generator. I have described a very simple one on the web pages to repair the Bally sound board ( type 2815-32 ) you can find out how to make such a generator on these pages.

Here a photo of the simple pulse generator, how to make it at Bally sound board repair type 2815-32 page.

All we need ,the loudspeaker and the cables.

How everything is connected ?

The male connector CN2 on the board has 6 pins the two on the left ( pin 5 and 6 ) are to connect the loudspeaker, put here the loudspeaker connector ( white arrow ) of the other four pins only pin 3 and 4 are connected at pin 4 comes ground ( = 0 volt ) on pin 3 comes +5 volts.( red arrow point at this 4 pins female-connector )

CN1 is the ribbon cable connector ( blue arrow) here the connections are as follows; to ground ( 0 volts) pins 2,7,10,11,17 and 18. To +5 volts pin 15, pin 8 receives the signal coming from the pulse generator, hook on the green grip of the pulse generator, the black and red grips of the pulse generator are to connect at +5 and ground ( the +5 can easely be taken at R39 upper side, and the ground at C1 lower side.) we also need pin 1+6 of the ribbon connector CN1 tied together, with that we launch the sound .. everytime we touch ground at those two wires tied together a sound will be produced.. Whe need also acces to pin 3 of CN1 to test the NE555 chip.

What is left is a red wire grip ( see photo yellow arrow) this wire clip is connected at +5 volt and must be hooked up at R38 upper side.

Drawing of the cables.

The complete mounting..From left to right the white connector in CN2 of the loudspeaker, the yellow connector bringing +5 and 0 to pins 3 and 4 of CN2, the black grip bringing 0 volts to the puls generator and hooked at C1 underside, the green grip bringing the pulses from the pulse generator at pin 8 of the ribbon cable , just under the green grip you see the blinking solder point that is in reality pin 1 and 6 soldered together and used to launch the sound by touching it with ground.And last the two red grips one bringing 5 volts at R38 ( upper side ) and the other bringing +5 at the pulse generator this one is connected to R39 upper side..

The schematic of the sound board.

How to use and repair.

Best case , the board produce a sound

When everything is connected we simply launch the sound by touching with ground the pins1 and 6 tied together. If the sound is heart you can assume the board is ok, this is the type of sound you will hear..

If a board works on the bench and does not in the pinball, control these things.. Is there +12 volt coming at pin 3 of CN2? If not you have a problem with the power supply .. If the 12 volts is ok at pin 3 of CN2 , look at pin 14 of IC2 ( SN76477) there you must find 8,2 volts , if not you have a problem with the circuit composed of DZ1, R1, C1,C2 . If ok measure at pin 15 of the IC2 there you must have 5 volts , if not your SN76477 is bad ...( The SN76477 contains a voltage regulator that stabilises any tension between 7 to 9 volt brought at pin 14 and that comes out at pin 15 as a steady +5 volts...That is why at the schematic they make a difference between the VCC ( +5 volts coming from pin 15 CN1) and the +5volts ( coming from the SN76477 from his pin 15, and derived from the +12 volts) . If all that is ok and the board still does not function , you are missing signals at the input connector CN1 and should look for a fault at the cpu outputs....

The board is silent....

If the board does not produce a sound when bringing 1+6 to ground for a brief moment, we start controlling the amplifier chip IC1 TDA1010.. First bring the 100K potmeter TR1 in the middle then touch with your finger the resistor R4 if the amplifier is ok you will hear a good humming, if not and no components seem to be burnt up around the IC1 replace the TDA1010... If the humming is there we start controlling the other signals needed to procuce a sound.

1) We inject a signal from the pulse generator at CN1 pin 8 , this signal enters at IC4 pin 9 and comes out this IC at pin 8, follow this signal with a logic probe, it enters now at IC5 at pin 4 and comes out at his pin 1, from there it enters at IC6 pin 9 and triggers the flip flops contained in this IC. If ever it enters in one of these IC's and does'nt come out the IC is bad..

2) If the flip flops receive the clock signal at pin 9 ( IC6) outputs should move when we ground pin 1+6 of CN1. So when doing this ( grounding a brief moment 1+6) look at pin 2 of IC6 it is normally High and should go Low.. If not the 74LS174 ( IC6 ) is bad.

3) We control now the status of the outputs 5 and 7 of IC6 both have to be high and go low when starting a sound, if ok the output of connected IC 5 at pin 13 is normally low and goes high when starting a sound.The signal now enters at IC4 pin 11 and comes out here at pin 10 where it is normally high and goes again low if a sound is started. Again if something is ok at an input and wrong at the output that chip is bad..

4) If the output at pin 2 of IC6 goes indeed low ,we have to control if the transistor Q6 reacts good. Look at R9 upper side if you have a low that goes high at starting a sound the transistor is ok, if not the transistor is bad.

5) now we control the NE555 chip, to do that ground pin 3 of CN1, and launch a sound ( this will be a different sound ... ) by grounding as usual pin1+6. If the 555 is ok his output at pin 3 is low and will give a high pulse. If not check the input signals coming from IC4 pin 2 and 4 they are both high and will go low at the launch of a sound. their inputs at pin 1 and 3 are inverted.. No input ? Look at point 6) where we control the IC7 74LS156 chip .

6) Last thing to control is the output of IC7, undo the ground connection at pin 3, when launching again the sound ( ground 1+6 ) the changes at the input pins 1 and 15 are; normally high going low , the outputs to control are pin 4 normally low going high , and pin 12 normally high going low...

7) If afther all these tests still no sound , replace the chip SN76477 ( IC2 )

Practical Tips.

Somethimes there is sound but merely a cracking sound , and certainly not the type of sound you hear on the two previous recordings... Examples of " wrong" types of sound are here...

In this case control the in- and outputs of the different selection IC's . To do so find hereafther the pins of all 4 IC's and how their pins should measure and change during the first type of test ( pin 3 not grounded) ; H=hight , L= low and if the pin changes it is indicated.

IC4 ( 4069) pin 1=H , 2=L , 3=H , 4=L , 5=H , 6=L , 7=L , 8=pulses, , 9=pulses , 10=H goes L , 11=L goes H , 12=L , 13=L , 14=H.

IC5 ( 4002) pin 1=pulses , 2=L , 3=L , 4=pulses , 5=L , 6=L , 7=L , 8=L , 9=H goes L , 10=H goes L , 11=H goes L , 12=H goes L , 13=L goes H , 14=H.

IC6 ( 174) pin 1=H , 2=H goes L , 3=H goes L , 4=H goes L , 5=H goes L , 6=H goes L , 7=H goes L , 8=L , 9=pulses , 10=H , 11=H , 12=H , 13=H , 14=H goes L , 15=H goes L , 16=H.

IC7 ( 156) pin 1=H goes L , 2=L , 3=H , 4=L goes H , 5=H , 6=H , 7=H , 8=L , 9=H , 10=H , 11=H , 12=H goes L , 13=H , 14=L , 15=H goes L , 16=H.

... Succes!

Extra

For personal use , I made a print on wich everything is assembled, and make it more handy to use than the loose connections.

The red push button to launch the sound, and the switch to ground pin 3 while testing the NE555. As the rest of the components is very restricted, the whole can be made for $4, in a few hours.....