Donkey Kong "siren" problem (not the nintendo hum!)....

linx310

Active member
Joined
May 30, 2006
Messages
281
Reaction score
84
Location
Kyle, Texas
Donkey Kong "siren" problem (not the nintendo hum!)....

Ok I am trying to figure what exactly causes the "siren" or "alarm" sound issue on Donkey Kong board stacks.

Video with audio from another member showing the issue

https://www.youtube.com/watch?v=vl1bEBO3RjM

Past threads covering the issue from various forums:

http://www.johnsarcade.com/forum/index.php?topic=2960.0
http://forum.arcadecontrols.com/index.php?topic=148896.0
https://forum.arcadeotaku.com/viewtopic.php?t=31442
https://forums.arcade-museum.com/showthread.php?t=368745
https://forums.arcade-museum.com/showthread.php?t=364831

Generally it is accepted that replacing Q4 or Q6 C1815 transistors will solve the issue. On some boards it works and others it does not.

I have 2 boards that have this issue. On both I replaced not only Q4 and Q6 but all the audio C1815 transistors (Q1-Q6). On one of the boards I also replaced the audio caps.
I checked 6L (the driver that activates the analog sounds) with a scope and it's not pulsing randomly so that's not it.

I checked out the switching Diodes D6 and D7 and they are behaving.

Stumped I decided to disconnect portions of the audio circuitry to see if I could isolate the cause.

Surprisingly it may not be part of the sound circuitry at all. We may have just assumed it was since it kind of sounds like a jumping sound. I disconnected the following which are marked in red on schematic I posted

R1 removed digital sounds.
R24 removed jump sound.
R2 removed donkey Kong stomping sound.
R14 removed walking sound.
I even removed the digital audio chip and CPU from the board.
I also swapped out video boards with others on board stacks that do not have this issue. No change so it is coming from the cpu board.

The "siren" sound is still present. If I disconnect capacitor C13 the sound disappears but this breaks the connection to the trace that the audio out is on so you can't hear anything anyways.

I have put the board in a stock DK cab and connected it to my supergun with one of Mike's DK to Jamma adapters (has a built in audio amp) and the sound is present in both so it is coming from the pcb.

Since past threads have always focused on the audio circuitry trying to solve this issue I wonder if that was a wild goose chase and the actual problem is noise coming from the one of the ICs on the board.

Perhaps a filter cap some place on the board is going bad or has failed?
 

Attachments

  • schdis.jpg
    schdis.jpg
    353.1 KB · Views: 46
Last edited:
Yes, the video you linked to above was from my DK machine.

Unfortunately, I could never figure out where that sound was coming from so I sent my board to Mikesarcade.com for repair.

Mike tried his darndest to pinpoint the that sound on my board but even he eventually gave up and ultimately traded me for a "non-siren" sound board.

So the siren sound remains a mystery! :(

It's really awesome you have documented your work thus far....I agree the sound is coming from somewhere strange on the board.
 
So the siren sound remains a mystery!

It's really awesome you have documented your work thus far....I agree the sound is coming from somewhere strange on the board.

Yea I think two different issue have been confused as one for some time.

Ex:
Issue 1: Boards that have a failing audio transistor causing the jump sound to repeat. These are solved by replacing the transistors mentioned above.

Issue 2: Boards that have a sound that mimics the jumping sound but is not originating from the audio circuitry. This is the issue that is unsolved atm.
 
Wow. I wonder if Adam from One Circuit has come across a fix for this. He works on a lot of Nintendo boards.
 
Screens from my scope on the audio out line.

Not an expert in audio waveforms so if any one has any thoughts....
 

Attachments

  • NewFile6.png
    NewFile6.png
    39.7 KB · Views: 31
  • NewFile9.png
    NewFile9.png
    41.4 KB · Views: 33
  • NewFile10.png
    NewFile10.png
    48.3 KB · Views: 34
The jump sound isn't decaying fully.... Pretty simple fix.

How isn't it decaying fully causing the audio if the audio circuitry for the jump is completely disconnected?

Whats the simple fix?
 
Last edited:
I had that sound on my dkjr but waaay louder.

I fixed it by replacing the caps before the amplifier.

It's on my dkjr semi restore to playable condition thread.

I forget the values but they were small.

One cap was factory wrong according to the schematics was a 20ish volt cap and the schematic was asking for 50v.

Which im my mind the capacitor never discharged, it kept a bit of a ghost in the machine sound going...

May not be the correct interpretations of what it was doing.

I also replaced one ic.

But mine is now fixed. ;)
 
Last edited:
I had that sound on my dkjr but waaay louder.

I fixed it by replacing the caps before the amplifier.

It's on my dkjr semi restore to playable condition thread.

I forget the values but they were small.

One cap was factory wrong according to the schematics was a 20ish volt cap and the schematic was asking for 50v.

Which im my mind the capacitor never discharged, it kept a bit of a ghost in the machine sound going...

May not be the correct interpretations of what it was doing.

But mine is now fixed. ;)

Yes, for some people this fixes the issue. In my case, (and I also suspect in the OPs case) it will not fix the issue.

I replaced every single cap and transistor on the audio portion of my board (twice) and that did not fix the issue.
 
Did mike swap board boards and narrow it to the cpu board or video board?

If this is an unresolved issue, that's kinda exciting...

What if it comes back on my board, and my fix was only masking the problems....


I'd like to know what Hudson believes the issue is.
 
Did mike swap board boards and narrow it to the cpu board or video board?

Unfortunately, I never got a answer to that from Mike. Wish I had...because at least that would have cut the problem in half.

I suspect the issue is isolated to the CPU board. That would make sense right?
 
Yes In my limited knowledge I would think so.

I have a spare dead dkjr board stack I need to work on so I can send it out to mike.

I need to find a cheap pp7b to rebuild and cables

So I can get a setup on my test bench.
 
Climb sound wrong pitch (very high) AND jump sound wrong pitch (too low). After replacing C17, C16, C22, and C19. I replaced 6L (4020) counter chip. That fixed it. Lesson here is that these two sounds share some common circuitry, so if both sounds are bad, try the common stuff first.

http://www.brasington.org/arcade/tech/dkj/

This is from brasington repair logs.
 
One cap was factory wrong according to the schematics was a 20ish volt cap and the schematic was asking for 50v.

Irrelevant... that section of the board sees 12V max.

Which im my mind the capacitor never discharged, it kept a bit of a ghost in the machine sound going...

May not be the correct interpretations of what it was doing.
Not even close to how capacitors work.
 
Did mike swap board boards and narrow it to the cpu board or video board?

If this is an unresolved issue, that's kinda exciting...

What if it comes back on my board, and my fix was only masking the problems....

Forgot to mention I did that. I swapped the video board out with one that wasn't doing it. No change so i don't think its the video board.
 
I would check the components and connections around the NE556 and the string of 3 inverters you can just barely see in original screen shot. I suppose the NE556 could be bad too.

When you say you swapped out all the audio caps I assume that includes cap in this area?
 
I would check the components and connections around the NE556 and the string of 3 inverters you can just barely see in original screen shot. I suppose the NE556 could be bad too.

When you say you swapped out all the audio caps I assume that includes cap in this area?

Yeap caps replaced in that area to. I did order a replacement 556 and chip that has the invertors but they wont be here till next week.
 
Here we go, Mark Spaeth acting inappropriately again.

I lack the knowledge and skills to assist the OP, otherwise I would.

Mark, how about you actually offer up some genuinely useful suggestions here to assist the OP? Or are you afraid you might actually suggest something inaccurate?

I just don't get it....

EDIT: So apparently my word choice was a bit strong for some, as it resulted in my receiving an infraction for my efforts. I will refrain from using strong similes in the future and just call inappropriate behavior "inappropriate."
 
Last edited:
Back
Top Bottom