(Topic ID: 138861)

Black Knight Sound Board Repair

By cody_chunn

8 years ago


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#1 8 years ago

I have posted this before within other threads, but in a blatant attempt to get in the compendium again it is posted here in it's own thread. Fingers crossed! Oh, and if you find any corrections let me know and I'll edit them in.

Black Knight Sound Board Repair

The following information was written specifically for a Williams Black Knight (’80) pinball machine. These procedures may also be used for other WMS games like Firepower. However, some signals may or may not be used for your model.

If you are reading this document, it is assumed that your BK sound board is not working. It is further assumed that there is NO sound AT ALL to begin with. If your board works somewhat, the fix may be mixed in with the procedures and you will have to pinpoint the failure with deductive reasoning. This document may be practically useless.

Complaint

My Black Knight will not make any sound during game play or sound diagnostic. (It is assumed that the game functions properly other than no sound).

The Basics

Before you even pick up a screwdriver, adjust the remote volume inside the lower cabinet on left side to center position. Also locate the adjustment knob on the Speech board and set it to the center position. The Sound/Speech boardset will be located at top right inside the backbox. A larger, square sound board (with four connectors along the top and a plug on the left) and a smaller, rectangular speech board connected to the sound board via 40 pin ribbon cable to the above-mentioned plug.

Check the orientation of the connectors on the sound board. Top left is J3, the select lines from the driver board (J9). Next is J4, the remote volume connector (the shield [bare wire] should be on left). J2 is the speaker connector. J1 at top right is the AC input for the sound board operational voltages (Gray wires). Make sure J2 and J4 are not swapped. There should be no open chip sockets on the sound board or speech board for BK (other games may have open sockets on speech board). All chips on the sound boardset are oriented with pin 1 (divot in corner of chip) pointing downward. Check all socketed chips for bent legs and straighten or replace as needed. If your meter is handy, check the two fuses on the sound board. If not, we will check them soon enough.

OK, so our cursory look in the backbox didn’t turn anything up. Now we need to check the lower cabinet. Open the door, release and remove the lockdown bar and slide the playfield glass out. Reach in the door, on the right (a few inches inside of the lockdown release lever), and work the ball release solenoid by hand to eject the three balls into the trough. Use caution not to mangle trough switches. Place the balls in a safe place. Lift the playfield and rest it against the backbox (you may want to secure the field so it can’t fall). Now inspect the remote volume potentiometer (pot) lugs. Gently tug on each of the three wires and resolder as needed. Inspect the two lugs on the speaker itself and resolder as needed.

Jumpers

Sound boards must be configured for the model machine they are being used in. This is accomplished with hardwired jumpers installed at locations around the board. The jumpers could be a piece of wire or a Zero-Ohm resistor, which is normally gray or tan with a single black stripe around the center. Black Knight should have the following configuration (please refer to game manual for other models):

W1 Not Installed (with Speech Board; if no speech board present, install W1)
W2 Installed
W3 Not Installed
W4 Not Installed
W5 Installed
W6 Not Installed
W7 Installed
W8 Not Installed
W9 Installed
W10 Installed
W11 Not Installed
W12 Not Installed ***Edited 12/26/15 this is "PB7 Status Control, with W13 never used. Can someone confirm on their BK sound board? Confirmed W12 NOT INSTALLED***
W13 Not Installed
W14 Installed (This is a foil trace jumper that is always present. It is located directly underneath R30, and ties one leg of that resistor to ground)

ROMs

The sound ROM for BK should be a White Label Sound ROM 5. The speech board should be fully populated with four ROMs.

DIP Switches

Located at top left corner of sound board by the diagnostic switch is DIP switch bank one (DS1). It consists of switch one and switch two. Factory settings with speech is switch one (on bottom) set to Off, and switch two set to On.

Capacitors
Black Knight sound board electrolytic capacitor list
C12/C30/C36 1 ų @ 63 Volt C26 1000ų @ 25 Volt
C14 800ų @ 16 Volt* C27 12,000ų @ 16 Volt
C15 500ų @ 15 Volt** C29 10ų @ 25 Volt-Low Leak
C25 100ų @ 10 Volt
It is recommended that all electrolytic capacitors on the sound boardset be replaced. C27 (12,000 microfarad @ 16 volt) should be replaced regardless.

Black Knight speech board electrolytic capacitor list
C12 10ų @ 25 Volt-Low Leak
Refer to game manual for component location.

Troubleshooting

Note: If the sound board is jumpered for a speech board (W1 out), it must have the speech board connected to work, and it is possible for the speech board to kill all sound. If you are unsure if the speech board is good or not, disconnect it, install W1 and repair. Then rejumper sound board and reconnect speech and repair.

The quickest form of troubleshooting is substitution. If you are fortunate enough to have another like-model game that works, you can swap boards to determine exactly what board is causing the failure. Furthermore, once that is done, you can swap socketed chips to eliminate those and prove they are good. Socketed chips can also be quickly replaced to eliminate them as suspects.
The underside of the connectors on all the boards in the game should be checked and the solder reflowed as needed. The header pins should be inspected and replaced if the pins are delaminating or pitted. Connector pins should be replaced along with the header pins.
I will assume you do not have another game to swap your board into (or another board to install in your game), and that the connectors look great. So let’s isolate the sound board by disconnecting J3. Now press the diagnostic switch on the sound board. If sound is restored, there is a locked signal on the driver board and it should be repaired. If still no sound, verify operational voltages are present at the test points on the sound board:

 Set multimeter to AC Volts. Probe from J1 pin 8 to J1 pin 2. Then from J1 pin 1 to J1 pin 9. Each time you should see about 18 Volts AC. If this voltage is missing or incorrect, trace the gray wires back to the transformer, and verify it is correct coming off the transformer. Remember that this voltage is also used to generate the +5, +12, and –12 used elsewhere in the game, so if only the sound is out, the AC should be correct.

 Set meter to Volts DC, 20 Volt range. Connect black lead to TP3 (ground). With red lead, probe:
TP1 = +12 Volts DC (positive reading)
TP2 = -12 Volts DC (negative reading) – If either TP1 or TP2 are incorrect or missing, make sure fuses and clips are good, then replace BR1.
TP4 = +5 Volts DC – If TP4 is incorrect or missing, but TP1 and TP2 are correct, replace IC8 and C27.
IC13 Pin 3 = -12 Volts DC – This is an input voltage originating from TP2, so find the broken trace between the two if missing.

If you have verified that all operating voltages are correct, you have gone about as far as you can go with a meter. Time to pick up a logic probe and/or scope probe. These two items are extremely useful, but still fall short of an oscilloscope for troubleshooting. However, the inexpensiveness of probes makes them affordable, and even if you can’t determine the cause of failure and have to send the board out for repair, you’re not out too much money.

Using the Logic Probe

The logic probe is one of the most efficient (CHEAP!) tools that can be used for troubleshooting logic problems. I do not claim to be an expert in the use of one, but I do know how to use one to help.
We will be using the sound board’s own diagnostic for these tests, so the first thing we need to do is verify the switch signal makes it to the CPU.

 Disconnect sound board J3.
 Connect the black clip lead of the logic probe to TP3 (ground).
 Clip the other lead (red or traced) to TP4 (+5V).
 Set logic probe to “Pulse” and “DTL/TTL” (not CMOS).
 Power up game and make sure it enters attract mode.
 Carefully apply the logic probe to IC9 pin 6. It should read “HI”.
 Depress the diagnostic switch. The line should drop LOW when the switch is depressed. If it does, the diagnostic switch and logic probe are operating properly. If not, find the problem with the diagnostic switch through continuity tests, or the problem with the logic probe (does it show a HI if you touch TP4?)

Let us assume that the switch and probe are operating properly, and that the NOT NMI line at IC9 pin 6 goes low when the diagnostic button is pressed. Now we need to check for pulsing on the sound CPU, IC9.

NOTE: When probing signals with a logic probe you can accidentally short two IC signal pins together, which can “crash” the board. It is suggested to cycle power between tests to make sure the sound CPU is running and not crashed/locked.

 Verify game is in attract mode.
 Depress sound diagnostic switch.
 Probe IC9 pins 9 through 20 (address buss outputs), and 22 through 33 (data buss two-way signals).
 If you see pulsing on all of these lines, the Crystal and CPU should be fine. Since the CPU is socketed, it would not be a bad idea to swap it into a working board or with a known working component if suspect.
 If you still get no pulsing, verify operational voltage is on the chip. Set meter to DC Volts and probe black lead to pin 1or 21 and red lead to pin 8 or 35. You should read +5 Volts. If you do not, verify TP4 is +5 Volts, then locate and repair break in continuity to IC9.
 If +5 Volts is present, replace the 3.58 MHz crystal.

The NOT NMI signal is a manual override that commands the CPU to initiate the memory test. So…

 Verify game is in attract mode.
 Depress sound diagnostic switch.
 Probe IC11 pins 17 through 23 and IC12 pins 1 through 8. They should all be pulsing. If not pulsing, locate and repair break in continuity to IC9.

IC11 (6810 RAM) and IC12 (Sound ROM) will interpret the above inputs and feed them out on their data lines.

 Verify game is in attract mode.
 Depress sound diagnostic switch.
 Probe IC11 pins 2 through 9. All should be pulsing. If not replace IC11.
 Probe IC12 pins 10,11, and 13 through 17. All should be pulsing. If not replace IC12.

So we have the CPU at IC9 pulsing and the RAM and sound ROM are pulsing. This information is then fed to the PIA at IC10.

 Verify game is in attract mode.
 Depress sound diagnostic switch.
 Probe IC10 pins 26 through 33. If not pulsing, locate and repair break in continuity to IC11/IC12.
 If pulsing, probe outputs of IC10 at pins 2 through 9. If one or more lines are locked HI or don’t pulse, replace IC10, PIA 6820/6821.

The data is then fed to the Digital-to-Analog Converter (DAC) at IC13.

 Verify game is in attract mode.
 Depress sound diagnostic switch.
 Probe IC13 pins 5 through 12. If not pulsing, locate and repair break in continuity to IC10.

The DAC takes the digital data and converts it to analog information that the amplifier can understand. It is fed through the 2N4401 transistor at Q2.

#2 8 years ago

Thank you for posting this. It's perfect timing for me as I begin work on a BK project. My sound is muffled and mixed up. Wrong sounds in wrong situations and speech that doesn't make sense. Will walk through your steps and hopefully find the issue.

Steve

3 months later
#3 8 years ago

Hi Cody - I have spent several hours trying to troubleshoot my BK sound while using your guide. First, I would say thanks for posting it. Second, I do believe that W12 should read "Not Installed" I did try jumpering that one and went from Almost dead to Completely dead.

In the end, I've ordered a working used board. Will probably swap ICs until I find the flaky one.

#4 8 years ago
Quoted from songofsixpence:

Hi Cody - I have spent several hours trying to troubleshoot my BK sound while using your guide. First, I would say thanks for posting it. Second, I do believe that W12 should read "Not Installed" I did try jumpering that one and went from Almost dead to Completely dead.
In the end, I've ordered a working used board. Will probably swap ICs until I find the flaky one.

Thank you for the info. It does appear that W12 shouldn't be installed for BK.

Can someone please take a look at their sound board and see if W12 is present or not? The original post has been edited, and I would like confirmation...I thought I had compared all jumpers with my board.

Would someone please help?

#5 8 years ago

I just got this Bk going a couple days ago. No w12 on the sound board.

image_(resized).jpegimage_(resized).jpeg

#6 8 years ago

Thank you so much, to both of you. Sorry I had an error in my write up. I hope it eventually helps you get your board up and running.

#7 8 years ago

I had tried to follow your instructions, but it seemed my Sound card wouldn't quite follow the script. Admittedly, I probably have the cheapest logic probe ever made. It seems to work worse after it gets warmed up. Here's a video of when it's powered on and a game started

After those words/sounds it stops working completely. If anyone has any advice, I'm happy to hear it.

#8 8 years ago

It sounds like it's stuck in diagnostic. To eliminate it, disconnect the speech board and install (temporarily) jumper W1. See if behavior changes. Just leave the speech disconnected until you get the sounds working.

#9 8 years ago

I did try that - same result.
I got my "working used" board today. Confirmed the jumpers, installed the BK rom and installed. The sound is... better. I don't have any speech now, but the other sounds seem correct.

This board has the original SCANBE socket and 30+ year old caps. Also I'm not confident in the connectors or the fuse clips. So, I will replace these. Stay tuned...

2 months later
#10 8 years ago

So for an update:

The sockets weren't SCANBE after all, so I think they are alright.

I had done some research, and read that sometimes IC3 on the speech board causes the symptoms that I was having. IC3 is a Dual 1458 OP AMP. Not available at Mouser. I found it on eBay, it took a couple weeks to get delivered from China. I ordered 10, so if you need one let me know.

It has fixed my issue, now the Black Knight is talking and making sense. I would say he's slightly more loquacious than Gorgar.

7 months later
#11 7 years ago
Quoted from cody_chunn:

I have posted this before within other threads, but in a blatant attempt to get in the compendium again it is posted here in it's own thread. Fingers crossed! Oh, and if you find any corrections let me know and I'll edit them in.
Black Knight Sound Board Repair
The following information was written specifically for a Williams Black Knight (’80) pinball machine. These procedures may also be used for other WMS games like Firepower. However, some signals may or may not be used for your model.
If you are reading this document, it is assumed that your BK sound board is not working. It is further assumed that there is NO sound AT ALL to begin with. If your board works somewhat, the fix may be mixed in with the procedures and you will have to pinpoint the failure with deductive reasoning. This document may be practically useless.
Complaint
My Black Knight will not make any sound during game play or sound diagnostic. (It is assumed that the game functions properly other than no sound).
The Basics
Before you even pick up a screwdriver, adjust the remote volume inside the lower cabinet on left side to center position. Also locate the adjustment knob on the Speech board and set it to the center position. The Sound/Speech boardset will be located at top right inside the backbox. A larger, square sound board (with four connectors along the top and a plug on the left) and a smaller, rectangular speech board connected to the sound board via 40 pin ribbon cable to the above-mentioned plug.
Check the orientation of the connectors on the sound board. Top left is J3, the select lines from the driver board (J9). Next is J4, the remote volume connector (the shield [bare wire] should be on left). J2 is the speaker connector. J1 at top right is the AC input for the sound board operational voltages (Gray wires). Make sure J2 and J4 are not swapped. There should be no open chip sockets on the sound board or speech board for BK (other games may have open sockets on speech board). All chips on the sound boardset are oriented with pin 1 (divot in corner of chip) pointing downward. Check all socketed chips for bent legs and straighten or replace as needed. If your meter is handy, check the two fuses on the sound board. If not, we will check them soon enough.
OK, so our cursory look in the backbox didn’t turn anything up. Now we need to check the lower cabinet. Open the door, release and remove the lockdown bar and slide the playfield glass out. Reach in the door, on the right (a few inches inside of the lockdown release lever), and work the ball release solenoid by hand to eject the three balls into the trough. Use caution not to mangle trough switches. Place the balls in a safe place. Lift the playfield and rest it against the backbox (you may want to secure the field so it can’t fall). Now inspect the remote volume potentiometer (pot) lugs. Gently tug on each of the three wires and resolder as needed. Inspect the two lugs on the speaker itself and resolder as needed.
Jumpers
Sound boards must be configured for the model machine they are being used in. This is accomplished with hardwired jumpers installed at locations around the board. The jumpers could be a piece of wire or a Zero-Ohm resistor, which is normally gray or tan with a single black stripe around the center. Black Knight should have the following configuration (please refer to game manual for other models):
W1 Not Installed (with Speech Board; if no speech board present, install W1)
W2 Installed
W3 Not Installed
W4 Not Installed
W5 Installed
W6 Not Installed
W7 Installed
W8 Not Installed
W9 Installed
W10 Installed
W11 Not Installed
W12 Not Installed ***Edited 12/26/15 this is "PB7 Status Control, with W13 never used. Can someone confirm on their BK sound board? Confirmed W12 NOT INSTALLED***
W13 Not Installed
W14 Installed (This is a foil trace jumper that is always present. It is located directly underneath R30, and ties one leg of that resistor to ground)
ROMs
The sound ROM for BK should be a White Label Sound ROM 5. The speech board should be fully populated with four ROMs.
DIP Switches
Located at top left corner of sound board by the diagnostic switch is DIP switch bank one (DS1). It consists of switch one and switch two. Factory settings with speech is switch one (on bottom) set to Off, and switch two set to On.
Capacitors
Black Knight sound board electrolytic capacitor list
C12/C30/C36 1 ų @ 63 Volt C26 1000ų @ 25 Volt
C14 800ų @ 16 Volt* C27 12,000ų @ 16 Volt
C15 500ų @ 15 Volt** C29 10ų @ 25 Volt-Low Leak
C25 100ų @ 10 Volt
It is recommended that all electrolytic capacitors on the sound boardset be replaced. C27 (12,000 microfarad @ 16 volt) should be replaced regardless.
Black Knight speech board electrolytic capacitor list
C12 10ų @ 25 Volt-Low Leak
Refer to game manual for component location.
Troubleshooting
Note: If the sound board is jumpered for a speech board (W1 out), it must have the speech board connected to work, and it is possible for the speech board to kill all sound. If you are unsure if the speech board is good or not, disconnect it, install W1 and repair. Then rejumper sound board and reconnect speech and repair.
The quickest form of troubleshooting is substitution. If you are fortunate enough to have another like-model game that works, you can swap boards to determine exactly what board is causing the failure. Furthermore, once that is done, you can swap socketed chips to eliminate those and prove they are good. Socketed chips can also be quickly replaced to eliminate them as suspects.
The underside of the connectors on all the boards in the game should be checked and the solder reflowed as needed. The header pins should be inspected and replaced if the pins are delaminating or pitted. Connector pins should be replaced along with the header pins.
I will assume you do not have another game to swap your board into (or another board to install in your game), and that the connectors look great. So let’s isolate the sound board by disconnecting J3. Now press the diagnostic switch on the sound board. If sound is restored, there is a locked signal on the driver board and it should be repaired. If still no sound, verify operational voltages are present at the test points on the sound board:
 Set multimeter to AC Volts. Probe from J1 pin 8 to J1 pin 2. Then from J1 pin 1 to J1 pin 9. Each time you should see about 18 Volts AC. If this voltage is missing or incorrect, trace the gray wires back to the transformer, and verify it is correct coming off the transformer. Remember that this voltage is also used to generate the +5, +12, and –12 used elsewhere in the game, so if only the sound is out, the AC should be correct.
 Set meter to Volts DC, 20 Volt range. Connect black lead to TP3 (ground). With red lead, probe:
TP1 = +12 Volts DC (positive reading)
TP2 = -12 Volts DC (negative reading) – If either TP1 or TP2 are incorrect or missing, make sure fuses and clips are good, then replace BR1.
TP4 = +5 Volts DC – If TP4 is incorrect or missing, but TP1 and TP2 are correct, replace IC8 and C27.
IC13 Pin 3 = -12 Volts DC – This is an input voltage originating from TP2, so find the broken trace between the two if missing.
If you have verified that all operating voltages are correct, you have gone about as far as you can go with a meter. Time to pick up a logic probe and/or scope probe. These two items are extremely useful, but still fall short of an oscilloscope for troubleshooting. However, the inexpensiveness of probes makes them affordable, and even if you can’t determine the cause of failure and have to send the board out for repair, you’re not out too much money.
Using the Logic Probe
The logic probe is one of the most efficient (CHEAP!) tools that can be used for troubleshooting logic problems. I do not claim to be an expert in the use of one, but I do know how to use one to help.
We will be using the sound board’s own diagnostic for these tests, so the first thing we need to do is verify the switch signal makes it to the CPU.
 Disconnect sound board J3.
 Connect the black clip lead of the logic probe to TP3 (ground).
 Clip the other lead (red or traced) to TP4 (+5V).
 Set logic probe to “Pulse” and “DTL/TTL” (not CMOS).
 Power up game and make sure it enters attract mode.
 Carefully apply the logic probe to IC9 pin 6. It should read “HI”.
 Depress the diagnostic switch. The line should drop LOW when the switch is depressed. If it does, the diagnostic switch and logic probe are operating properly. If not, find the problem with the diagnostic switch through continuity tests, or the problem with the logic probe (does it show a HI if you touch TP4?)
Let us assume that the switch and probe are operating properly, and that the NOT NMI line at IC9 pin 6 goes low when the diagnostic button is pressed. Now we need to check for pulsing on the sound CPU, IC9.
NOTE: When probing signals with a logic probe you can accidentally short two IC signal pins together, which can “crash” the board. It is suggested to cycle power between tests to make sure the sound CPU is running and not crashed/locked.
 Verify game is in attract mode.
 Depress sound diagnostic switch.
 Probe IC9 pins 9 through 20.
 If you see pulsing on all of these lines, the Crystal and CPU should be fine. Since the CPU is socketed, it would not be a bad idea to swap it into a working board or with a known working component if suspect.
 If you still get no pulsing, verify operational voltage is on the chip. Set meter to DC Volts and probe black lead to pin 1or 21 and red lead to pin 8 or 35. You should read +5 Volts. If you do not, verify TP4 is +5 Volts, then locate and repair break in continuity to IC9.
 If +5 Volts is present, replace the 3.58 MHz crystal.
The NOT NMI signal is a manual override that commands the CPU to initiate the memory test. So…
 Verify game is in attract mode.
 Depress sound diagnostic switch.
 Probe IC11 pins 17 through 23 and IC12 pins 1 through 8. They should all be pulsing. If not pulsing, locate and repair break in continuity to IC9.
IC11 (6810 RAM) and IC12 (Sound ROM) will interpret the above inputs and feed them out on their data lines.
 Verify game is in attract mode.
 Depress sound diagnostic switch.
 Probe IC11 pins 2 through 9. All should be pulsing. If not replace IC11.
 Probe IC12 pins 10,11, and 13 through 17. All should be pulsing. If not replace IC12.
So we have the CPU at IC9 pulsing and the RAM and sound ROM are pulsing. This information is then fed to the PIA at IC10.
 Verify game is in attract mode.
 Depress sound diagnostic switch.
 Probe IC10 pins 26 through 33. If not pulsing, locate and repair break in continuity to IC11/IC12.
 If pulsing, probe outputs of IC10 at pins 2 through 9. If one or more lines are locked HI or don’t pulse, replace IC10, PIA 6820/6821.
The data is then fed to the Digital-to-Analog Converter (DAC) at IC13.
 Verify game is in attract mode.
 Depress sound diagnostic switch.
 Probe IC13 pins 5 through 12. If not pulsing, locate and repair break in continuity to IC10.
The DAC takes the digital data and converts it to analog information that the amplifier can understand. It is fed through the 2N4401 transistor at Q2.

Thank you much for a comprehensive overview of things to look at. I'm working my way down your list and I'm at the point where I have the sound board jumpered so it can run on its own and I'm still getting nothing. I'm tossing around the idea of getting new caps because my C27 looks really discolored and a bit corroded. That being said there's no guarantee new caps will fix my problem. My overarching question then is -- at what point is it worth it to cut your losses and order the new boards as opposed to spending money continually trying to replace parts onesy-twosy on the boards? Anyone got ideas on this?

Thanks much.

2 weeks later
#12 7 years ago

Sorry to wade into the conversation at such a late date, but my problem is indeed the sound board-

The Schematic, along with other posts tell me the voltage inputs for J1 should be +/-12 Volts, however mine looks like this:

P1 P5 P9
-10.6V C +10.6V

Will this 10.6V suffice? and if not, what do I do to fix it?? One of the documents says: Follow the leads down to the transformer and find out what's wrong. The transformer has a huge shield over it, and it appears the wires in question connect to the transformer in the most inaccessible place possibly in the entire machine. So as not to have to spend forever upside down, what might I be looking for? Just if the base of the 3 wires reads the same? I'll wait before I go Transformer diving. Haha.

Thanks in advance.

-Brian

#13 7 years ago

oopsie. Is it possible to delete a post? I didn't know how to mark a topic as finished until Ralph told me!
-Brian

#14 7 years ago

J1 pins 1 to 9, and pins 2 to 8. You should see about 18VAC between each pair.

#15 7 years ago

How does that jive with mine? This is a black knight..

IMG_4506 (resized).JPGIMG_4506 (resized).JPG

#16 7 years ago

And.. j1 shows 1,5 &9..? I think I'm about to feel so stupid in a second...

IMG_4508 (resized).JPGIMG_4508 (resized).JPG

#17 7 years ago

Is that a sound board for an earlier system? It looks like the one they used in the lower cabinet on earlier systems?

I am confused...

#18 7 years ago
Quoted from bdPinball:

How does that jive with mine? This is a black knight..

Set your meter on AC voltage. Put one lead of your meter on the first wire in the connector and the other meter lead on the wire in the 9th position of the connector (opposite ends) and you should read ~18V AC.

Pin 5 is the center tap of the transformer coil (connected at the 1/2 way point in the transformer coil). You should get ~1/2 of the AC voltage (~9V AC) with one meter lead on pin 5 (center of the connector) to either pin 1 or 9 (either end of the connector).

#19 7 years ago

Thank you very much Schwaggs- I believe that IS what I'm getting.

So why the discrepancy in boards? Is this an earlier board? I have a Flash I'm half working on as well, so I'm interested to know! (That sound board works!)

-Brian

#20 7 years ago

No, it looks like the right board. That partial diagram confused me for a minute. Pin 5 is tied to ground. Pins 1 and 2 are tied together on the board, as are pins 8 and 9. So you should see the AC voltage from pin 1 or 2 to 8 or 9.

#21 7 years ago

TPs are 12V or better on 1 & 2, +12.98 and -14.25 respectively, However #4 reads 4.92. Is that the problem? sorry for being ignorant about these types of things. When I see readings listed on blueprints, or other posts I can never tell if they have to be exact, it's okay to be a little higher, or a little lower.

Rule of thumb a little higher is better than a little low? is .08 V enough to be TOO low though?

-Brian
Electronic Apprentice

#22 7 years ago

Hey! I got him to talk! If he's warmed up, and I press the the test button, it'll make a couple of quick noises and then quit. Restart, Press game start, and he says, "I-" and then it quits.

I was following the test procedure above, and things were going well - Except for the slightly low 5V. So, I did the logic probe test of the test- Woo Hoo! I love using the logic probe! here's how it read when Probing Pins 9-20:

9- \-
10- I
11- I
12- > 9-14 are just solid hi/lo.
13- I
14- /
15-\
16- I
17- I
18- > 15-20 were all pulsing to some degree-
19- I 15-19, fairly quickly, and 20 VERY fast
20-/

#23 7 years ago

Okay... after tracing all the way down the procedure at the top of this, more or less, I think I have figured it out:

at IC10.

 Verify game is in attract mode.
 Depress sound diagnostic switch.
 Probe IC10 pins 26 through 33. If not pulsing, locate and repair break in continuity to IC11/IC12.
 If pulsing, probe outputs of IC10 at pins 2 through 9. If one or more lines are locked HI or don’t pulse, replace IC10, PIA 6820/6821.

Right here, I have inputs at 26-33, but the outputs from IC10, PIA6820 doesn't have any outputs on 2-9.

I think I'll wait for someone to give me a thumbs up on this being a good course of action. I'm lucky as hell to actually have these chips in my stockpile! I ordered both the 6821, and the 6808P a few years ago (well, maybe 10) they don't go bad or anything right?

-Brian

#24 7 years ago

All of the outputs are HI, LO, NO SIGNAL?

Do you have +5VDC between pin 20 and pin 1?

#25 7 years ago

Yes- 2-9 on IC10 all seem to be locked low. Yes, There is 4.9V between Pin 1 and 20 of IC10.

As you suggested I swapped out the 6808. Easy enough to do.

-Brian

#26 7 years ago

If it's socketed, yes replace the 6820/1. If not, since ALL outputs are LO, before heating up all those pads you might want to check a couple more lines.

R/W at pin 21; Chip Selects @ pins 22,23,24; /RESET @ pin 34 (should be HI)...compare the signals to a 6820/1 on the CPU board...unless there's a control line keeping the chip from functioning it looks like the 6820/1 is bad. I've just never seen ALL outputs of a PIA be locked unless one of the control lines was keeping the chip from working.

#27 7 years ago

First, let me say I'm new to the Logic probe, so Maybe I'm not fully understanding it's output. In several places, we check 7? lines Anyway, starting at IC9, the set of 7 strobing lines to test. But when you test the lines the Strobing, or beeping, isn't the same for each line. Some seem to pulse faster, and some slower. A Couple of the lines are pulsing so fast they don't seem like they're pulsing at all. Does that make sense? Maybe I need to do the test and record it or something so you can understand.. It seemed like MOST of the lines were strobing though.. Am I reading a couple of those strobes wrong? If 5 of the lines are strobing, and 2 of them are sort of just sitting there.. Is that normal? If they all strobed at exactly the same speed I would sort of know what to look for- these are all at different rates. Is it an all or none type of thing, where if most them are strobing, the thing is working, or do the lines have a tendency to give out one at a time?

That 6820 is NOT socketed. The CPU was, so I swapped that out, I can't tell if it made it any better or not. But yes, I was hoping for a little more confirmation before I undertake the task of replace that 40 pin. I do have a 40pin socket to put in there when I do it, or maybe I won't do it, and bring it to one of my electronics friends to have him swap out the chip.

-Brian

PS- To be clear, I've taken the (J4) cable to the CPU off so the Sound card is isolated as per the instructions..
r

#28 7 years ago

Your additional description sounds more like what I'm used to seeing when probing a bad PIA. The outputs should be pulsing about the same frequency as the inputs. They can vary in frequency from pin to pin. They can also be pretty much any combination of HI/LO/PULSE (with HI or LO on, off, or pulsing), as long as the PULSE is there is the important thing.

So if you are probing the outputs and get LO=ON SOLID, HI=OFF and PULSE = BLINKING, that is a VALID GOOD signal.

Yes, in my experience, there is usually only 2 or 3 lines not pulsing but that is enough to kill the logic (actually 1 is enough).

#29 7 years ago

I have a friend replacing the 40 pin pia with a socket. We'll plug in the new chips and say a prayer or two.

#30 7 years ago

Thanks for posting your progress. I hope my instructions haven't led you to replace a chip unnecessarily. Let us know either way.

#31 7 years ago

Well, it can't hurt to get a chip planted on that spot anyway for future problems. It also helps that I had the chip laying around if I didn't and had to order it it might be a different story.

#32 7 years ago

Of course, it might not fix the problem either. Hahaha.

Okay, Back to the beginning. I think what I've done wrong is earlier on, when I saw SOME activity on the 1-7 lines I thought maybe I was just misreading the other lines. I'll go back and do the entire process and note at which point those lines drop out. I think it's pretty quick after IC9? The first one? I'll let you know what I dig up. I'm determined to get this damned board to work. It'd probably just be easier to buy a damned Rottendog replacement, and the guy who installed the 40 pin socket told me the board was in pretty rough shape and he didn't anticipate it working forever.

It WAS working just a few weeks ago! Sure it's been around the block, but It's not like at the bottom of a stack of junk boards or something, I KNOW the board worked - and fairly recently. I had had some problems with it, and I re-capped some of the larger Caps that were obviously buldging, and the board started working again for a month or two, before developing whatever this current problem is. I'll let you know a new status when I go downstairs and run the Logic Probe over it again.

-Brian

#33 7 years ago

Yes, that's why I cautioned you to take another look if *all* the outputs were wonky.

Someone else working on this sound board indicated you could cut down troubleshooting in half basically by probing/connecting a small speaker in places to see if the pre-amp sound is being generated. That's a good short cut but I didn't research it.

I wanted my document to be a methodical approach from start to finish that should discover the fault every time (yeah, right) no matter where it lies. I sincerely hope it leads you to the right conclusion and the next component you replace is the correct one to repair its functionality.

#34 7 years ago

Yes, There is NO STROBING on Pins 11, 12, & 13 of IC 9. That is in the first set of instructions after we test the Test button to see if 6 goes Hi/lo when you push the button. 9, 10, and 14-20 all have strobing.

What does this say?

Oh- Confession. When I was just testing it again, to see if there was -12 at IC13 pin 3, but I touched the lead to 2 & 3, and it fried the lead between #3 c28. I repaired the lead on the back side of the board with a little jumper. Shit happens. Did that likely screw anything else up?

-B

1 year later
#35 5 years ago

Hello all... Reviving this thread as my Firepower stopped emitting sounds, and I found plenty of great info here...

Just a quick question: I have 11.75V on TP1 and -13.25V on TP2... Is it acceptable ? TP4 is 4.95V.

Thanks!
Mat

#36 5 years ago

I would opine those values are within tolerance.

#37 5 years ago

Hey, BD, sorry I didn't respond a year ago. I hope you got your board fixed.

1 week later
#38 5 years ago

Thanks for the reply (sorry took me 7 days, I was out of town...). Good to know the 12V is in range, I need to look elsewhere...

So far:
- I had the sound stopping intermittently, now it is always off
- TPs give reasonably correct voltages
- When I adjust the volume pot up an down, the "hum" is getting softer/louder, so I guess the audio amp and speaker are OK
- I bridged w1, removed the ribbon cable, and put the switch "2" off to remove speech... still no sound at all
- I replaced the main caps, they looked old... it did not fix the issue.
- When I put my logic probe on IC9/6 it changes to LOW if I actuate the diag switch. However when I don't touch the switch it, it's sometimes HIGH, sometimes not connected at all (?)... pins 9 to 20 are not pulsing (most of them HIGH)
- I thought it could be bad contacts at IC9 so I replaced the IC socket with a new one... no change.
- I noted the 6808 was getting quite warm, not sure if normal

Any idea of additional troubleshooting ? Thanks!

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