Q*Bert sound board kicking my ass

zork40

Active member
Joined
Nov 3, 2006
Messages
1,713
Reaction score
18
Location
Westerly, Rhode Island
Hey Guys,

I have a Q*Bert sound board that is a bit screwy. I thought I was only missing one sound but I am actually missing a lot more. Some sounds don't play, others are wrong. When you play the game, if you didn't know how Q*Bert should sound you probably would never notice the difference.

It does say "Hello, I'm turned on" when you power it up. Most game sounds work, but the speech seems a bit off. This video is from MAME and shows how the sounds SHOULD be:


This is how mine sounds:


If you compare both videos, you'll start to notice the difference with sound 04 which my Q*Bert doesn't make. Several other sounds are missing, and the speech doesn't sound right.

I've seen the Q*Bert sound flowchart, and have been using that as a guide.

Details on what has been done so far:

  • Power supply board has the zener diode mod, and voltage is OK
  • Filter board has been gone over, and I believe it is OK
  • I tested all the connectors on the filter board
  • I replaced all the sockets on the sound board
  • I replaced all the caps on the sound board
  • I replaced A10 on the CPU board
  • I replaced U16 on the sound board
  • I just replaced U17 on the sound board
I have a 6532 chip on order for U15 so I'm going to try that next. I've read that this might be due to a bad SC01 speech chip which seems to be pretty difficult to find so I hope that's not the case.

Anyone have any ideas here?

Thanks!
 
Sounds to me like one of the multi turn pots needs to be adjusted. It adjusts the pitch of the sounds. I believe its the second one in from the edge of the pcb. In other words top right of the sound board, second pot down.
 
Hi Riptor,

Thanks for the info. I see two pots in the lower right hand corner of the sound board as it sits on the back door. They are labeled R6 and R13. Those must be the ones you are talking about.

Do these have default values that they should be set to?

I tried adjusting both of these, first the left and then the right. I counted my turns so I could put it back the way it was.

When I adjust the one on the right, if I go to far to the right the sound gets distorted but doesn't seem to affect any speech sounds. When I go too far to the left, the regular sounds go away and I'm left with only speech.

When I adjusted the one on the left, I didn't hear any changes at all.

Is there a default ohm value I can set these to? How far should I turn them? For the left one, I started with a few turns. When nothing changed, I went to 10, then 20, and so on. I got all the way up to 80 turns with no noticeable change. I then went back to my starting point and went the other way 80 turns and still no change.

What about the dip switches on the board? I can't find any info on what they do so I'm guessing nothing. They are all ON right now.

I noticed some battery corrosion on R1, R2, R3, and the capacitors around them.

example.jpg

I'm going to replace those and clean that up to be safe. Do you think that could have anything to do with this?
 
The dips do absolutely nothing and it doesnt matter what position they are in.
Also some sounds in test mode do not make any noise, this is normal. I cant tell you which ones off the top of my head.
I will get some readings for the pot so you can get them in the neighborhood. Watching your video it seems all the sounds are there but the pitch of the speech sounds are definitely way off. One of those two multi turn pots is out of adjustment. Its possibly you could have a bad speech chip too.
R6 2.58KΩ
R13 4.75KΩ
These dont have to be exact, just get them somewhat close.
 
Last edited:
You need to slow down the speech by turning the pot Riptor mentioned. One of those pots is the amplification and the other controls the speech frequency. If you have any speech, which you do, the SC-01 is fine. Play with that pot to get the correct speed/frequency for the speech. Dont worry about the "corrosion", its likely a little oxidation. Very typical. As Riptor mentioned, there are 3-4 sounds on the test mode that do not produce sounds.
 
Thanks guys, much appreciated especially at this crazy hour!

I set my R6 and R13 to what Riptor has as a starting point. It didn't help.

I'm thinking something else is going on here. I am missing sounds beyond the ones that are normally empty. The normally empty/missing sounds are 16, 29, 30, 31, and 32. I'm missing sounds 4 and 20 and they do play in MAME.

The 2nd video in my first post is how mine sounds. Compare to the first video and you'll see what I mean.

Sound 22 is the one that got me working on this. On mine, it is a constant pitch with no speech, and sounds screwy. Sound 23 isn't right either. If you compare those two in my Q*Bert video to the MAME video there is a big difference. In the MAME video, 22 and 23 have a speech sound that raises and lowers.
 
Do you have known verified roms, good 6502 & a 6532? Did you double check your work? Lifted pads, solder glob, no bent pins exc.. And your sure the A10 on the main is good? I think its something easy as there are too many sounds to be something else, from my experience.....
 
Do you have known verified roms
I don't have a way to tell. I don't have a ROM burner/reader to check them. I don't think the ROM test in test mode tests those if I remember right.

, good 6502 & a 6532?

I have a 6532 on order. It should be here tomorrow or the day after. I'll let you know if that helps. I have not changed the 6502, not sure if it is OK or not.

Did you double check your work?
Yup, as best as I could. This did this from day one before I worked on the board so I don't think anything I did caused it. I did go over it like crazy to make sure everything seemed OK, but I'm not a pro.

your sure the A10 on the main is good?
I had put a new one in. Just for the hell of it, I just put another new one in and its the same.

I think its something easy as there are too many sounds to be something else, from my experience.....

I'll see what happens when I replace the 6532. I'm hoping its not the SC01 as I probably won't find one of those.
 
I just got the 6532 and swapped it out, and its still the same.

Would the SC01 be the most logical chip to suspect now? I guess I'll need to find a working sound board.
 
I have only had a couple bad Sc-01's in the 50+ Qbert sound boards I have repaired. Of those that had a bad SC-01, they had no voice at all. So, I think its unlikely its the
Sc-01...possible, but unlikely.

If your following that flow chart, there are a few more chips that it mentions. The yes / no questions are not fool proof exactly when following the chart. Check the other chips in the line with a logic probe or you could carefully piggy back them to see if you get a change.
 
Thanks for the reply.

On that flowchart, if you go to the left (Yes) on 'Says "Hello Im turned on"', I've replaced every chip on that left side of the flowchart.

I didn't go towards the right side of the flowchart. If I do, that would probably point me to either:
U14
U13
U12
U9

I'll see if I have any of those logic chips and see if it gets me anywhere.
 
I have found alot of times if you have missing or wrong sounds its the chip right above the LS30...cant remember off the top of my head what it is. The most common failure on the sound board is the LS30 but that will almost always yield no sound at all.
If you need any chips hit my website. I have everything on the sound board except the dip resistor networks.
 
I have found alot of times if you have missing or wrong sounds its the chip right above the LS30...cant remember off the top of my head what it is. The most common failure on the sound board is the LS30 but that will almost always yield no sound at all.
If you need any chips hit my website. I have everything on the sound board except the dip resistor networks.

Are you talking about the 6502 chip at U3?


@Takeman:
BTW - regarding U13, U12, and U9 - I only have a chip for U13. I carefully piggy backed it and when I turned it on the "Hello, I'm turned on" sounded garbled. However, when I jump off the board the "OHHHHHHH" was present and it wasn't before. The sound coily makes when he jumps off is still completely screwed.
 
Nope, the LS04. Sorry, I always consider the edge connector the top of the board.
You did replace the 74LS377 on the main board A10 right? They go bad if you look at them wrong.
 
If you had a sound improvememt when you piggy backed u13, give that a shot.
 
One more thing, the 470uf cap is often bad. I typically always replace that one and then test the 47uf ones and replace those only if needed.
 
Thanks guys. I just ordered some chips from Riptor. When they come in I'll mess with this some more and let you know how I make out.
 
Update: I've changed U9, U13, and U12 with no improvement.

I started testing with my meter set to continuity and I think I may have found a short. When I put the leads from my meter on the pads for C40 it tones out. I pulled a leg out, and it still tones out with the leads on the pads. That's not normal, is it?

I tried tracking down the short but can't find it.

There are some jumper wires and intentionally cut traces on the back of the board. I figured those were factory mods, but I really don't know. Does anyone have a close up pic of the back of the sound board for comparison?
 
Back
Top Bottom