(Topic ID: 302539)

External subwoofer sound issue (JJP Wonka)

By SDpinballer

2 years ago


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  • 17 posts
  • 3 Pinsiders participating
  • Latest reply 2 years ago by mbwalker
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#1 2 years ago

This is my Wonka set up for sound. It’s worked well for over a year or two. Recently, the sound on the entire machine will intermittently cut out; come back on for a 10-15 seconds then cut out for a 10-15 seconds. It will keep cycling like that. If I unhook the external sub input wires, by disconnecting the alligator clips, the problem goes away (but then of course I don’t have subwoofer sound). In addition, I’m not sure if this is supposed to happen - but when I was unhooking the alligator clips while the game and the amplifier/subwoofer were on, there was enough current in the wire to spark (as I was physically removing the wire from the terminal). So right now, just playing the machine stock, and would like to hook the subwoofer back up and have it work correctly. I have tried several times and it keeps on doing it cycle on and off thing. Any advice would be appreciated!

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#2 2 years ago

I'd bet the external amp is fried, causing it to overdrawn the stock system.

#3 2 years ago
Quoted from titanpenguin:

I'd bet the external amp is fried, causing it to overdrawn the stock system.

I was thinking that might be the case. Any idea how to test that? In the meantime, I’m going to take the amp apart and look at it.

#4 2 years ago

Not familiar with the amp, but the fact that if you remove it from the system it fixes the issue, I'd say it's a safe bet

#5 2 years ago
Quoted from titanpenguin:

Not familiar with the amp, but the fact that if you remove it from the system it fixes the issue, I'd say it's a safe bet

Thanks! I agree. I’ll post the process and solution.

#6 2 years ago

The amp board looks pretty good I guess. There is some corrosion on the underside that I cleaned up. I’ll reinstall it see if it helped at all.

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#7 2 years ago

I don’t know if it made a difference or not. I didn’t keep it on long enough to see. Usually the problem of cycling on/off sound starts after about 3 to 4 minutes of play. Reason I didn’t leave it on long enough is because even with the amp off, the sound coming from the cabinet speakers up top is scratchy when the alligator clips are attached. If I detach them, then the scratchy sound goes away. makes me question the connection at the alligator clips and connection point? There’s good connection and the terminals appear clean. Hmmmmm

#8 2 years ago

Best way to rule out alligator clips is to solder

#9 2 years ago

Electrical engineer here.

So I think you are running the cabinet sub straight into the input of the amp for an external sub? That's a high level signal (i.e. drives a speaker) whereas the external amp's input is low level (i.e. small signal). Might not be the actual culprit, but if you get another amp, that's one thing that should be addressed.

They make a high-level to low-level adaptors that are used in car stereos - it allows you to tap off a speaker and convert it to a low level signal appropriate for an external amp's input. Perfect for a pin and connecting an amplified sub. Also provides ground isolation which can be important. And it also is a Balun (BALanced to UNbalanced). Takes a balanced output (some newer pin's amp are balanced) and converts it to single-ended (i.e. the ext amp's input). A balanced output is where the woofer's output '-' is not ground (i.e. one wire is '+', one is '-'). Single-ended is where one is '+' and the is 'ground'. I use the adapter in all my pins just to be on the safe side whether needed or not. I hope that made sense.

Also, the possible corrosion mentioned? That just might residual solder flux. Hard to tell by looking at the pictures.

Link: https://www.amazon.com/SCOSCHE-LOC80-2-Channel-Adjustable-Converter/dp/B00009UHRE/ref=pd_sbs_2/144-7710882-9647537

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#10 2 years ago

Adding to my post above, is the external amp running off of +12V or 120V?

#11 2 years ago
Quoted from mbwalker:

Adding to my post above, is the external amp running off of +12V or 120V?

Definitely appreciate the info. I have ordered the high-low adapter. The amp is 12v5a. I hope the pic helps answer.

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#12 2 years ago
Quoted from SDpinballer:

Definitely appreciate the info. I have ordered the high-low adapter. The amp is 12v5a. I hope the pic helps answer. [quoted image]

Hi @sdpinballer. So are you saying you don't use and AC adapter and run off a straight 12V?

If you truly run off of 12V from the pin, then there might be the chance the negative 12V is at ground potential of the pin. A little hard to describe but it goes back to my balanced output comment going into a single-ended input. So if the amp output is -woofer (i.e. not ground) and +woofer, and it goes into the amp which the is +input, ground...that might be the underlying issue since the -woofer is now connected to ground. For some reason, I see people not using the adapter and somehow get away with it. Haven't given it much thought tho.

If you have a 12V AC adapter, then it might not be a problem since the amp is isolated from the pin (amp ground is not pin ground). Even a two prong vs. 3 prong 120V plug could make a difference too.

I should add that this is all speculation and maybe the amp just went south after working a couple of years. But like I mentioned, the adapter eliminates some issues regardless, doesn't hurt if not needed.

On the adapter, put alligator clips on two of the leads (either pick left or right input), then plug a RCA connector from the adapter output to the amp input.

Here's a little SnipIt I threw together to help visualize the wrong way to do it.

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And here's the proper way.
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Holler if I need to clarify anything!

Added over 3 years ago:

"Negative 12V" Probably not the best term to use since it sounds like -12V. Should have worded it to maybe the "12V return".

#13 2 years ago
Quoted from mbwalker:Hi SDpinballer. So are you saying you don't use and AC adapter and run off a straight 12V?
If you truly run off of 12V from the pin, then there might be the chance the negative 12V is at ground potential of the pin. A little hard to describe but it goes back to my balanced output comment going into a single-ended input. So if the amp output is -woofer (i.e. not ground) and +woofer, and it goes into the amp which the is +input, ground...that might be the underlying issue since the -woofer is now connected to ground. For some reason, I see people not using the adapter and somehow get away with it. Haven't given it much thought tho.
If you have a 12V AC adapter, then it might not be a problem since the amp is isolated from the pin (amp ground is not pin ground). Even a two prong vs. 3 prong 120V plug could make a difference too.
I should add that this is all speculation and maybe the amp just went south after working a couple of years. But like I mentioned, the adapter eliminates the issue regardless, doesn't hurt if not needed.
On the adapter, put alligator clips on two of the leads (either pick left or right input), then plug a RCA connector from the adapter output to the amp input.
Here's a little SnipIt I threw together to help visualize.
Holler if I need to clarify anything!
[quoted image]

@mbwalker. Sorry about late response. I have from the wall a two prong power cord that goes to a AC adapter, then into the 12 V5A labeled port on the amplifier. Input into the amplifier is direct connection from the speaker terminal. Speaker terminal two alligator clip RCA cables that I stripped, then input RCA cable adapters into the amplifier. output from amplifier goes directly left (red), left (black) to the speaker. When I get a replacement amp, they’re only 40 bucks, I will look for one with a three prong. But since it’s not completely useless, and the problem starts 3 to 4 minutes in to using it, I’m gonna try the adapter first and see if it makes a difference. Thank you for the information, truly appreciate. Like the diagram that you put together for me

#14 2 years ago
Quoted from SDpinballer:

mbwalker. Sorry about late response. I have from the wall a two prong power cord that goes to a AC adapter, then into the 12 V5A labeled port on the amplifier. Input into the amplifier is direct connection from the speaker terminal. Speaker terminal two alligator clip RCA cables that I stripped, then input RCA cable adapters into the amplifier. output from amplifier goes directly left (red), left (black) to the speaker. When I get a replacement amp, they’re only 40 bucks, I will look for one with a three prong. But since it’s not completely useless, and the problem starts 3 to 4 minutes in to using it, I’m gonna try the adapter first and see if it makes a difference. Thank you for the information, truly appreciate. Like the diagram that you put together for me

No need for a 3 prong. Only reason I mention 2 prong vs. 3 prong is the 3 prong might have grounded the external amps's chassis. Whereas the ext amp chassis might have been floating with a 2 prong. With the adapter (high-level to low-level) - it's a moot point. You're good w/whatever you buy.

Sorry, might have muddied the water a bit with 2 vs. 3 prong comment. I try to keep a reply kinda short and not get too wordy - can all turn to mush if too long.

#15 2 years ago
Quoted from mbwalker:

No need for a 3 prong. Only reason I mention 2 prong vs. 3 prong is the 3 prong might have grounded the external amps's chassis. Whereas the ext amp chassis might have been floating with a 2 prong. With the adapter (high-level to low-level) - it's a moot point. You're good w/whatever you buy.
Sorry, might have muddied the water a bit with 2 vs. 3 prong comment. I try to keep a reply kinda short and not get too wordy - can all turn to mush if too long.

Appreciate you guys on this thread. I’ll keep it updated when I get the parts.

#16 2 years ago
Quoted from mbwalker:

Link: amazon.com link »

This fixed the entire problem. The sound System performs better than it ever has now. No cutting out, no scratchy, bass sounds really good. Thank you so much!!!

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#17 2 years ago

Yay! A happy ending!

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