Main Restorations Software Audio/Jukebox/MP3 Everything Else Buy/Sell/Trade
Project Announcements Monitor/Video GroovyMAME Merit/JVL Touchscreen Meet Up Retail Vendors
Driving & Racing Woodworking Software Support Forums Consoles Project Arcade Reviews
Automated Projects Artwork Frontend Support Forums Pinball Forum Discussion Old Boards
Raspberry Pi & Dev Board controls.dat Linux Miscellaneous Arcade Wiki Discussion Old Archives
Lightguns Arcade1Up Try the site in https mode Site News

Unread posts | New Replies | Recent posts | Rules | Chatroom | Wiki | File Repository | RSS | Submit news

  

Author Topic: Calling electronics gurus: help me fix this speaker/subwoofer set  (Read 2744 times)

0 Members and 1 Guest are viewing this topic.

SirPeale

  • Green Mountain Man
  • Global Moderator
  • Trade Count: (+23)
  • Full Member
  • *****
  • Offline Offline
  • Posts: 12963
  • Last login:August 04, 2023, 09:51:57 am
  • Arcade Repair in New England
    • Arcade Game and Other Coin-Op Projects
I recently obtained a speaker/subwoofer set.  There is static coming from the right speaker, but only when there is sound.

I've been able to eliminate the speaker as the culprit, as well as the op amp chip.

What are other things I can look at to get this running without static?

AlexKidd

  • Trade Count: (0)
  • Full Member
  • ***
  • Offline Offline
  • Posts: 52
  • Last login:July 28, 2010, 06:46:24 pm
Re: Calling electronics gurus: help me fix this speaker/subwoofer set
« Reply #1 on: April 24, 2007, 10:44:04 pm »
Can you still hear music/game sounds coming out of the speaker with the static or is it just the static. Does turning up the volume affect the volume of the static?

SirPeale

  • Green Mountain Man
  • Global Moderator
  • Trade Count: (+23)
  • Full Member
  • *****
  • Offline Offline
  • Posts: 12963
  • Last login:August 04, 2023, 09:51:57 am
  • Arcade Repair in New England
    • Arcade Game and Other Coin-Op Projects
Re: Calling electronics gurus: help me fix this speaker/subwoofer set
« Reply #2 on: April 25, 2007, 01:14:25 am »
Can you still hear music/game sounds coming out of the speaker with the static or is it just the static. Does turning up the volume affect the volume of the static?

You can hear stuff, but it's practically all static.  And yes, the volume controls the volume of the static.

ChadTower

  • Chief Kicker - Nobody's perfect, including me. Fantastic body.
  • Trade Count: (+12)
  • Full Member
  • ***
  • Offline Offline
  • Posts: 38212
  • Last login:July 30, 2025, 03:29:53 pm
Re: Calling electronics gurus: help me fix this speaker/subwoofer set
« Reply #3 on: April 25, 2007, 09:20:00 am »

Have you tried swapping the speakers?  A speaker with a bad driver coil sounds like that.  Think pinball coil in this context, same thing, one winding per speaker cone.

SirPeale

  • Green Mountain Man
  • Global Moderator
  • Trade Count: (+23)
  • Full Member
  • *****
  • Offline Offline
  • Posts: 12963
  • Last login:August 04, 2023, 09:51:57 am
  • Arcade Repair in New England
    • Arcade Game and Other Coin-Op Projects
Re: Calling electronics gurus: help me fix this speaker/subwoofer set
« Reply #4 on: April 25, 2007, 10:48:21 am »
I've been able to eliminate the speaker as the culprit...

ChadTower

  • Chief Kicker - Nobody's perfect, including me. Fantastic body.
  • Trade Count: (+12)
  • Full Member
  • ***
  • Offline Offline
  • Posts: 38212
  • Last login:July 30, 2025, 03:29:53 pm
Re: Calling electronics gurus: help me fix this speaker/subwoofer set
« Reply #5 on: April 25, 2007, 10:52:37 am »
Hrm... the speaker output circuit is probably analog, so I'm thinking there are some bigger caps and inductors in there.  I'd start with those since they are things that can degrade but not take the whole circuit with it.  Compare readings on them with the same circuit for the other speaker.  Clean up/inspect all of the removable connections, too, like molexes and header pin connections.  It's worth reflowing them all on principle.

EDIT:  BTW, how did you eliminate the op amp?  I don't know how to test those directly yet.  It sounds useful.
« Last Edit: April 25, 2007, 10:59:33 am by ChadTower »

SirPeale

  • Green Mountain Man
  • Global Moderator
  • Trade Count: (+23)
  • Full Member
  • *****
  • Offline Offline
  • Posts: 12963
  • Last login:August 04, 2023, 09:51:57 am
  • Arcade Repair in New England
    • Arcade Game and Other Coin-Op Projects
Re: Calling electronics gurus: help me fix this speaker/subwoofer set
« Reply #6 on: April 25, 2007, 11:03:51 am »
EDIT:  BTW, how did you eliminate the op amp?  I don't know how to test those directly yet.  It sounds useful.

It's not the most expensive speaker set in the world.  I figured the op amp might be the culprit, so I went looking for a replacement.

I found a pair of powered speakers in the attic I thought *might* have a compatible chip.  It didn't - it had the EXACT chip.  Since those speakers work just fine, I swapped it out.  The problem persisted.

Not the most technical way to do it, but it worked.  ;)

I've already done the usual reflowing of joints on the PCB.  Likely I could shotgun the entire board without much issue (other than actually tracking down the parts).

ChadTower

  • Chief Kicker - Nobody's perfect, including me. Fantastic body.
  • Trade Count: (+12)
  • Full Member
  • ***
  • Offline Offline
  • Posts: 38212
  • Last login:July 30, 2025, 03:29:53 pm
Re: Calling electronics gurus: help me fix this speaker/subwoofer set
« Reply #7 on: April 25, 2007, 11:09:57 am »

Ah, so you pretty much know everything I could help you with, I think.  I was hoping you had learned some nice method for testing op amps.   ;D  I'm sure there is one out there somewhere.

BobA

  • Trade Count: (+14)
  • Full Member
  • ***
  • Offline Offline
  • Posts: 5943
  • Last login:July 11, 2018, 09:52:14 pm
  • What Me Worry?
Re: Calling electronics gurus: help me fix this speaker/subwoofer set
« Reply #8 on: April 25, 2007, 01:51:52 pm »
If your speaker set has a headphone or earphone jack try jacking a connecter in and out a few times to dislodge any dirt that might be on the contacts.   I have found that these jacks corrode over a period of time and mess up the speaker output since the signal goes thru them and they are really cheaply made.

Just to cover all bases try this will all the jacks and plugs in the system.

Chris G

  • Well then throw me in a dress and call me Sally
  • Trade Count: (+3)
  • Full Member
  • ***
  • Offline Offline
  • Posts: 1039
  • Last login:April 16, 2023, 04:39:59 pm
  • Robotron in progress? I'm on my way.
Re: Calling electronics gurus: help me fix this speaker/subwoofer set
« Reply #9 on: April 25, 2007, 01:58:23 pm »
You're not testing with a white noise CD, are you?   ;D

MonMotha

  • Trade Count: (+2)
  • Full Member
  • ***
  • Offline Offline
  • Posts: 2378
  • Last login:February 19, 2018, 05:45:54 pm
Re: Calling electronics gurus: help me fix this speaker/subwoofer set
« Reply #10 on: April 25, 2007, 02:15:02 pm »
Last setup I fixed with this issue had a volume bad pot (of all things).  Other problems I've had causing this kind of behavior are bad AC coupling caps, lifted/poorly connected ground traces, and bad connectors.

I presume you've tested this with various sources and all exhibit the same problem?

Do you have a scope?  A very effective method for finding the problem is to put a nice pure sine wave in at a reasonable amplitude and probe around until you see something that isn't a sine wave anymore (clipped, tons of added harmonics, etc.), following the signal path.  You can accomplish something similar by probing around with a speaker attached to a high-impedance amplifier, listening for when it starts to sound bad.

SirPeale

  • Green Mountain Man
  • Global Moderator
  • Trade Count: (+23)
  • Full Member
  • *****
  • Offline Offline
  • Posts: 12963
  • Last login:August 04, 2023, 09:51:57 am
  • Arcade Repair in New England
    • Arcade Game and Other Coin-Op Projects
Re: Calling electronics gurus: help me fix this speaker/subwoofer set
« Reply #11 on: April 25, 2007, 04:51:58 pm »
Last setup I fixed with this issue had a volume bad pot (of all things).  Other problems I've had causing this kind of behavior are bad AC coupling caps, lifted/poorly connected ground traces, and bad connectors.

Bad pot - maybe.  Too bad I don't have one I can swap in quickly to test.

Quote
I presume you've tested this with various sources and all exhibit the same problem?

Actually, no.  I'm sure my source is clean (my computer).  This is a speaker set I got out of a dumpster.  I'm sure this is why it was there.

Quote
Do you have a scope?  A very effective method for finding the problem is to put a nice pure sine wave in at a reasonable amplitude and probe around until you see something that isn't a sine wave anymore (clipped, tons of added harmonics, etc.), following the signal path.  You can accomplish something similar by probing around with a speaker attached to a high-impedance amplifier, listening for when it starts to sound bad.

Nope, no scope.

AlexKidd

  • Trade Count: (0)
  • Full Member
  • ***
  • Offline Offline
  • Posts: 52
  • Last login:July 28, 2010, 06:46:24 pm
Re: Calling electronics gurus: help me fix this speaker/subwoofer set
« Reply #12 on: April 25, 2007, 10:40:57 pm »
Two diagnostic techniques that are easy are to turn it on and turn the volume up a bit and start tapping on parts of the board with a non conductive probe of some sort, maybe the plastic handle of a screwdriver or something. See if tapping on anything affects the static. If it does then whatever you are tapping on could be bad or have some bad solder joints. The other technique is to use freeze spray and spray it onto different components on the board and see if that affects the sound at all.

A burnt up resistor would cause those symptoms although usually those are pretty easy to spot because they are blackened or brown and the board is sort of burnt around them. Tapping or freezing those will affect the static too usually. If you had a scope you could look at the signal at different points along it's path and see where it is getting distorted.

ChadTower

  • Chief Kicker - Nobody's perfect, including me. Fantastic body.
  • Trade Count: (+12)
  • Full Member
  • ***
  • Offline Offline
  • Posts: 38212
  • Last login:July 30, 2025, 03:29:53 pm
Re: Calling electronics gurus: help me fix this speaker/subwoofer set
« Reply #13 on: April 26, 2007, 08:19:03 am »

I'm sure you did, but just in case, did you swap out the wire harness(es) to make sure it's not something in there instead of the speaker itself?

MaximRecoil

  • Trade Count: (+1)
  • Full Member
  • ***
  • Offline Offline
  • Posts: 1729
  • Last login:September 12, 2022, 09:50:44 pm
Re: Calling electronics gurus: help me fix this speaker/subwoofer set
« Reply #14 on: April 26, 2007, 05:16:40 pm »
Are these PC speakers? If so, have you tried them in a different PC? Sometimes the problem is with the sound card, or more specifically, the soundcard's female 1/8" miniplug input.

SirPeale

  • Green Mountain Man
  • Global Moderator
  • Trade Count: (+23)
  • Full Member
  • *****
  • Offline Offline
  • Posts: 12963
  • Last login:August 04, 2023, 09:51:57 am
  • Arcade Repair in New England
    • Arcade Game and Other Coin-Op Projects
Re: Calling electronics gurus: help me fix this speaker/subwoofer set
« Reply #15 on: April 26, 2007, 07:32:22 pm »

I'm sure you did, but just in case, did you swap out the wire harness(es) to make sure it's not something in there instead of the speaker itself?

I didn't swap the wiring for two reasons.  1) tight tolerances, it's kinda cramped in there and 2) I'm quite certain there's nothing wrong with it.

Are these PC speakers? If so, have you tried them in a different PC? Sometimes the problem is with the sound card, or more specifically, the soundcard's female 1/8" miniplug input.

I stated above that I didn't believe there was anything wrong with the input as I'd tried other speakers out on it.

Nevertheless I wanted to eliminate the possibility, so I plugged in my wife's MP3 player and my son's CD player.  Same thing.