Williams Black Knight (Williams, 1980) No Sound

[tenmile]

Black Knight Pinball Sound System

Symptom
No speech or sound from machine but unit appears to work.

History
I purchased this machine a couple of weeks ago and it has never had sound. The previous owner said it had sound at one time.

Supply Voltages
• TP1 +`12.6 VDC 800mV ripple
• TP2 -13.2 VDC, 400 mV ripple
• TP3 ground
• TP4 +5VDC, 240 mV ripple

CPU Board Check
Momentary pushing diagnostic button on CPU caused users displays to blank, LED on CPU to flash once the digit display on CPU board to indicate 0. Unit then unit goes back to attract mode, both LED go out, digit display on CPU board goes blank.

Information
D8224 Sound Board
C8226 Speech Board
Sound Rom5
2K ROM (White Label)
Board Jumpers
• W2, 5, 7, 9, 10, 15 connected
• W1, 3, 4, 6, 8, 11, 12, 13 not connected
• W15 has no connection

Sound Board
Disconnecting Speech board, adding jumper for W1, putting DS1 switch 1 and 2 to off and momentarily pushing diagnostic switch provides on sound or speech.

Adjusting volume control below playfield provides hum from speaker at max volume. Injecting 1 KHz sine wave at Pin4 of IC13 (audio output) produces sound.

IC9 microprocessor
Monitoring IC9-6 with an oscilloscope and pressing the diagnostics button cause voltage to go from 5VDC to 0 VDC the back to 5VDC. Before pressing the diagnostics button pins 26-33 (address lines)have no activity but when diagnostics button is pressed I see signals of 5VDC Vp-p that are changing. Pins 5-12 (data lines to IC13) have no activity at any time.

Now with all that said
I’m guess IC9, micro sends data to IC12 the ROM/PROM then IC12 send the information to IC 11 the RAM which then send information back to the IC9 and then to IC13

I could not find a theory of operation for the D8224 sound board and need to know the order in which IC9, IC10, IC11 and IC12 communicate to troubleshoot further.

Thanks

 

[pinballdaveh]

according to the manual jumper chart W12 should be connected with games using white label rom. the rest of your jumper info is correct. it doesnt say anything about jumper W1. also check or replace capacitors C29 10mfd and C12 1mfd. they are in-line with the signal path. if they are bad they may prevent the signal from getting to the amplifier, since you injected a signal to find the amplifier section to be good.

 

[tenmile]

Black Knight No Sound

Thanks for the help and please correct me if I get any of this wrong.

Jumper w12 is questionable, jumper 12 shows going to IC10-17 which is an input. It would go low to cause certain sounds. The board shows no indication a jumper was every there. By pressing SW1 the diagnostics switch, I think would bypass this signal in ether state.

W1 is the jumper that is used if the Speech module is not used. To simplify the trouble shooting I have the speech module disconnected and the sound module out of the pinball machine on the bench with a 12VDC plus and minus supply hooked up. The 5VDC is derived from the 12VDC supply.

C29 and C12 are couple capacitor so by injecting a 1KHZ sine-wave at IC13-4, audio output and hearing the tone would eliminate the common base transistor Q2 and the Op Amp IC1 which includes C29 and C12.

I’ve order a rebuilt module so I can use this module as a reference of voltages and signals. I have also found most of the data sheets for the IC’s to determine the in and outs and IC requirements so maybe I can figure it out but again I would welcome any help.