(Topic ID: 24713)

jokerz! hum service tip - interpretation please

By toyotaboy

9 years ago


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  • 33 posts
  • 15 Pinsiders participating
  • Latest reply 4 months ago by Zee
  • Topic is favorited by 3 Pinsiders

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#1 9 years ago

Ok I'm 95% sure I have this right, but want another pair of educated eyes to look at it before I make permanent mods to my CPU. Here's a clean version of the service tip:
http://www.videoengine.com/pins/jokerz/jokerzpix/level4/jokerzservicetip.pdf

Here's what my pcb looks like:

1.JPG 2.JPG

Mostly I want to make sure that they are asking me to slice away the trace. If so, what's the best way to do that, scrape it with an x-acto?

#2 9 years ago

Not sure if you did already, but make sure all your screws are tight on all the boards in the backbox and replace if any are missing! loose or missing screws will cause a hum. I had this hum noise on my HS and check my boards and was missing several screws. I pulled one and headed to the hardware store to get more, installed screws and no more hum noise! If you already did this then proceded on grasshopper!

#3 9 years ago

jeff_phx: Yes, all the screws in and tight. There's a known issue with jokerz!, where they didn't isolate the sound channel for some reason (missed in the board spin? I don't know), so this is a service bulletin to "reduce" the hum (doesn't totally eliminate), but believe me it's an annoying hum when it's not modded.

Does the board look like it matches the bulletin? I don't want to start cutting traces, but it sure looks like that's what they are saying to do

#4 9 years ago
Quoted from toyotaboy:

Does the board look like it matches the bulletin? I don't want to start cutting traces, but it sure looks like that's what they are saying to do

That's what it looks like to me.

#5 9 years ago

I would put some heat shrink over the cap and resistor leads, as they could short out to other components pretty easily.

#6 9 years ago
Quoted from johnwartjr:

I would put some heat shrink over the cap and resistor leads, as they could short out to other components pretty easily.

agreed.. probably going to shorten the leads too (just threw them on to post a photo). This may not even fix it (I hear if "helps"). Another forum said it went away completely when they took the ground off the spinner in the backbox for the cards, but then it couldn't spin (so it awarded bonus as default). Sounds like there's just a bad ground in the design.

#7 9 years ago

Don't know if it's your photo or my eyes but your C8 looks like it has a bit of bulge to it...

And yes, cut the trace with an xacto and shrink tube over the leads.

viperrwk

#8 9 years ago

well mod is done, didn't seem to help any. Found this thread about removing grounds until it goes away to find source, or replacing bridge rectifiers on the powerboard:
http://www.gamesforum.ca/showthread.php?p=2293734

#9 9 years ago

Yes. I had a service call for some very loud nasty hum on a Jokerz and replacing the bridge on the power supply removed most of the noise and doing the factory mod removed the rest. I did not remove any grounds, but I have seen that work in old Bally sound boads.

#10 9 years ago
Quoted from kbliznick:

I had a service call for some very loud nasty hum on a Jokerz and replacing the bridge on the power supply removed most of the noise and doing the factory mod removed the rest

cool, good to know. Well I'm starting with replacing all the caps first (since they do dry up, causing weird fluctuations in voltage). If that doesn't work I'm replacing the rectifier. Thanks for confirming.

1 week later
#11 9 years ago

caps replaced, didn't help. Listened REALLY carefully, found it was mostly coming from the left speaker, so I clipped it.. sure enough, hum went away (sound still comes out of other 2 speakers). can't believe all this trouble, and all I really needed to do was replace a bad speaker

$12 w/free shipping with prime:
amazon.com link »

we'll see if the hum is still silent when I hook a speaker back up

1 month later
#12 9 years ago

A few years ago I replaced EVERY thing on both power supply, and sound boards. I mean everything, amps, caps, transistors, you name it.I even replaced the volume control wire with a better shielded one. Hum is still there. The worse noise you get is the flashers send a buzz over the speakers. It's said to be a cross talk with-in the board it's self, and not necessarily repairable. I did the update on the rear of the board, and it did not help. Yes you sever the trace completely, but please ignore my oops, as I went a little too far, hence the white jumper wire to fix.

#13 9 years ago

A few years ago I replaced EVERY thing on both power supply, and sound boards. I mean everything, amps, caps, transistors, you name it.I even replaced the volume control wire with a better shielded one. Hum is still there. The worse noise you get is the flashers send a buzz over the speakers. It's said to be a cross talk with-in the board it's self, and not necessarily repairable. I did the update on the rear of the board, and it did not help. Yes you sever the trace completely, but please ignore my oops, as I went a little too far, hence the white jumper wire to fix.

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#14 9 years ago

I too have replaced every component on both sound board and powerboard (except bridge rectifier). My hum is only there when the left speaker is hooked up. If I remove it, it's quiet as can be (and it's not the speaker, I tried swapping that too). I'm down to either a bad cable for the left speaker, or there's just gremlins in the machine. If that's the case, I may just splice the sound from the lower speaker into the top speaker and call it a day. I know it won't be stereo, but it's better than a hum.

#15 9 years ago

I've been all over this topic with some of the best. I believe looking at the schematic, Jokerz is a kind of mock up stereo set up, Yes there are 2 separate audio channels, but there is no real left and right. it's the same signal split over the 2 channels. I added the Pinball pro speaker kit, and a parts express 100 sub amp to my game for that extra punch. Unfortunately it somewhat amplified the buzz, and hum. I think I even did new speaker wires from the sound output as well as new volume wire. I also did the bridge rectifier, and the main transistor as well.

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#16 9 years ago
Quoted from toyotaboy:

My hum is only there when the left speaker is hooked up.

If you hook up the left speaker, but don't let it touch ANYTHING metal, does it still hum?

So if the speaker is connected, but the frame is sitting on a piece of styrofoam, does it hum?

#17 9 years ago
Quoted from vid1900:

If you hook up the left speaker, but don't let it touch ANYTHING metal, does it still hum?

I believe I tried that (just left the speaker lying on the wood, removed all the ground wires), didn't help but I'll double check

1 year later
#18 7 years ago
Quoted from toyotaboy:

I too have replaced every component on both sound board and powerboard (except bridge rectifier). My hum is only there when the left speaker is hooked up. If I remove it, it's quiet as can be (and it's not the speaker, I tried swapping that too). I'm down to either a bad cable for the left speaker, or there's just gremlins in the machine. If that's the case, I may just splice the sound from the lower speaker into the top speaker and call it a day. I know it won't be stereo, but it's better than a hum.

So I too have a Jokerz with the BUZZ! just replace all the caps in P/S pcb, and no improvement. Is this a lost cause?

#19 7 years ago

I remember talking to the guy at the Coin Op Cauldron, he felt that the hum is coming from cross talk on the board, built-in interference if you will...

#20 7 years ago
Quoted from Silvercoin:

So I too have a Jokerz with the BUZZ! just replace all the caps in P/S pcb, and no improvement. Is this a lost cause?

Start disconnecting speakers to see which speaker is emitting it. I really did end up splicing the left speaker to the right. I also noticed the buzz went away when I disconnected the motorized cards in the backbox, so there's definitely some weird RF noise going through the audio.

#21 7 years ago
Quoted from toyotaboy:

Start disconnecting speakers to see which speaker is emitting it. I really did end up splicing the left speaker to the right. I also noticed the buzz went away when I disconnected the motorized cards in the backbox, so there's definitely some weird RF noise going through the audio.

Just a minor correction in terms, not likely RF (radio frequency) noise that you are experiencing but "inductive" noise. The motor and associated driving circuits create fields of magnetism that affect nearby circuits, propogating through wires in many cases, or even the traces on the boards. The problem is the noise gets in way early in the audio stream. Everything mixing and amplifying downstream is going to aggravate it, and it can be very difficult to remove the root cause.
I spent a lot of time on my DE Maverick, and what helped the most was floating the sound board. It's the only game I have had this actually reduce the noise on. Floating the ground is somewhat counter intuitive to my nature, but I work in pro audio stuff so I am familiar with ground loop problems so I gave it a try. This is part of the reason why our pro audio products are often designed with highly isolated digital and analog grounds.

#22 7 years ago

For those who read this thread - I did this Mod it greatly reduced the hum I had, but did not eliminate it, good enough for my game room. The shown example is correct and its worth doing for sure.

#23 7 years ago

I have "floated" sound boards a few times on SYSTEM 9/11 and DE pins to help determine the cause of the hum. So far I have found these causes of HUM (most common problems toward the top):

missing screws or missing GROUND (braided wire) connection in the backbox
bad connection on plugs
bad speaker
bad amplifier on sound board/MPU
bad caps on sound board/MPU
bad diodes/resistors on sound board
bad caps on power supply
bad potentiometer in cabinet or sound board
bad connector/open solder joints
low/high voltage on sound board
bad motor in the game somewhere
bad GI bulbs/sockets/feature lamp wiring (I know, a very strange one)

I use the "floating" trick but only after first checking all the above things.

I actually owned a Jokerz! long ago and my hum went away after I performed a playfield swap. I assumed that it was probably a bad connection on the playfield lamp matrix or GI somewhere.

#24 7 years ago

As with another poster, MOST of my issue is shooting through the left speaker. If I duplicate the sound from the right side am I missing anything sound wise? Music or FX?

Since it is the left sound channel, what in the schematics if you trace them could be the culprit?

I can't believe in the 25 years of this machines existence that a fix for the BUZZ hasn't been found.

The hum is there too but it doesn't bother me so much. the BUZZ makes my machine very unplayable.

I am gonna poke around, re-seat things. But I am gonna redo my speaker also if this can't be permanently fixed.

#25 7 years ago

Toyotaboy, did you ever replace the Bridge on the P/S pcb?

#26 7 years ago
Quoted from Silvercoin:

If I duplicate the sound from the right side am I missing anything sound wise? Music or FX?

My buzz was so bad, I don't know what was coming out of left speaker. Based on videos I've seen on youtube, I don't think I was missing any sounds. Even IPDB says it uses a "special version of stereo", which to me says not real stereo?

Quoted from Silvercoin:

Toyotaboy, did you ever replace the Bridge on the P/S pcb?

No, I didn't get that far, though I've read other threads where they've replaced it and it didn't help. It almost seems random where the issue starts. Supposedly many machines shipped with varying buzzing levels.

1 week later
#27 7 years ago

OK! So some progress.

The hum is like 90% gone, and the buzz is no more!

What did I do? I disconnected the motor that spins the card wheel. Thats it.

Loud buzz that made you not play the game. GONE!

Loud Hum that was almost as bad as the buzz, 90% GONE!

So, I think I will order a new motor? Maybe the quality will be better?

Jokerz is fun again!!

#28 7 years ago

You may want to check the resistance of the motor to see if it's still within spec...

You may also want to try to ground the frame of the motor to see if the hum goes away before you just assume it's bad.

#29 7 years ago

So here is where the learning curve happens, how do I check the resistance of the motor?

Grounding the frame I get...

#30 7 years ago

I just recently owned a Jokerz! which had a constant hum as well and it sort of increased to a buzz when the cards spun. It is sold now and it never really bothered me too terribly much but it's interesting to know that it wasn't just my machine and that this is actually a factory issue.

1 week later
#31 7 years ago
Quoted from Silvercoin:

So, I think I will order a new motor? Maybe the quality will be better?

I can only see that happening if it's a brushed motor and the brushes are severely worn. Some resistors and diodes may help (don't know the values). I know when I was racing r/c cars, they started doing that to get rid of some of the noise because higher RPM motors would actually interfere with the radio

3 years later
#32 3 years ago
Quoted from Silvercoin:

OK! So some progress.
The hum is like 90% gone, and the buzz is no more!
What did I do? I disconnected the motor that spins the card wheel. Thats it.
Loud buzz that made you not play the game. GONE!
Loud Hum that was almost as bad as the buzz, 90% GONE!
So, I think I will order a new motor? Maybe the quality will be better?
Jokerz is fun again!!

So I have the same issue with my Jokerz, and when I unplug the motor, no issue. With it plugged in, the sound is very bad, and the machine occasionally resets when both flippers are pressed! Unplugged, plays fine. Any ideas?

3 years later
#33 4 months ago
Quoted from toyotaboy:

I can only see that happening if it's a brushed motor and the brushes are severely worn. Some resistors and diodes may help (don't know the values). I know when I was racing r/c cars, they started doing that to get rid of some of the noise because higher RPM motors would actually interfere with the radio

Not a brushed motor. It's a stepper motor.

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