Help With Troubleshooting Car Stereo (Speaker) Problem

[General_T]

Hi,

The driver side front speaker has not worked in quite some time and I decided it was time to try and fix it.

I took the door panel off to have a look and hopefully see something obvious (loose wire), unfortunately there was nothing obvious. So I tried replacing the speaker with a brand new one, but again no sound/no change.

Next I dismantled the car dash and took the stereo out and dismantled it to have a look inside. I did find a bad capacitor 16v 2200uF (bulged top) which I replaced with a 25v 2200uF cap (supplier didn't have a 16v replacement). Replaced the stereo but still no change/no sound.

Now what I would like to do is test the unit in my house but IOT do this I need to power the unit. I was thinking of using a 12v lawn tractor battery and was hoping for some instruction in how to do this safely.

I managed to find the pin assignment on the back of the PC Board (Yeah!!). If anyone knows what TM means please let me know.

Here are some pics of the stereo unit.

My questions are:

• How do I connect the 12v power supply to the power pin on the stereo? I cannot find a connector that I can use. Is there somewhere to purchase a proper connector?
• Where do I ground this to complete the circuit?
• Is there anyway to test the speaker outputs without powering the stereo?
• Which pin is power I thought ACC but I read somewhere that ACC = Accessories?

[kaboom]

Re: Help With Troubleshooting Car Stereo (Speaker) Problem

You won't be doing any testing w/o a heatsink, I hope.

Ohm out the four spkr ckts by measuring at the connector that plugs into the stereo.

[General_T]

Re: Help With Troubleshooting Car Stereo (Speaker) Problem

Hi Kaboom,

I measured the outputs for the 4 speakers (there is no power on the stereo).

All 4 speakers showed 122 ohms. So does this mean that the circuit is good and that there may be a short in one of the wires going to the front left speaker? Man its gonna suck to try and find that if that's the case. I looked under the dash and there are a hockey sock bunch of wires all covered up with foam - a real rats nest!!

Please explain what you mean about a heatsink?

Thanks

[kaboom]

Re: Help With Troubleshooting Car Stereo (Speaker) Problem

Hi Kaboom,

I measured the outputs for the 4 speakers (there is no power on the stereo).

All 4 speakers showed 122 ohms. So does this mean that the circuit is good and that there may be a short in one of the wires going to the front left speaker? Man its gonna suck to try and find that if that's the case. I looked under the dash and there are a hockey sock bunch of wires all covered up with foam - a real rats nest!!

Unless those are differential line outs feeding a remote amp, those readings, each from the four individual SP+es/SP-es, should be more like 3 ohms DCR.

Please explain what you mean about a heatsink?

Thanks

There's a large multipin IC with 4 small caps next to it. I suspected that it was a 4 channel BTL audio power amp. But with those readings, I'm not sure at the moment...

If it is a power amp, you'll have to put it back in its chassis so it won't over heat.

Do you get a reading from any of those eight "speaker" leads to the body of the automobile?

Also, if the amp is working properly, you'll have 6-7VDC from both speaker leads (at the speakers) to chassis GND.

Should one of the leads to a speaker short to ground, the amp may shut down both output legs to avoid DC offset. Otherwise, while the shorted lead will be at zero, the other will have the normal, 1/2 supply voltage, offset. This would net ~6V thru the voice coil. Hence, both legs of the bridged channel(s) are dropped in the event of a short.

This only applies to BTL amps, usually providing ~20WPC into four ohms.

[cadiman]

Re: Help With Troubleshooting Car Stereo (Speaker) Problem

If this is a factory system it is very common for the speaker voice coils to go open mostly from slamming the car doors.

I replace door speakers all the time. (GM cars) I check them with a 9 volt battery to the speaker terminals or ohm them with a meter (4 to 10 ohms) at the terminals of the speaker.

In your case it looks like the radio is the problem.

Any bench testing should be done with a 10 amp fuse in line from the battery or power supply.

As said above you will need a heat sink back on the output ic or it will burn up the second you turn up the volume if you do get it to come on.

I go to the junk yards to cut the radio pigtails out of wrecked cars for my test plugs.

[General_T]

Re: Help With Troubleshooting Car Stereo (Speaker) Problem

Hi Kaboom,

This is a pretty basic stock radio (Clarion HCD5064) from a Hyundai Santa Fe 2003. Its rated for 100 Watts max - 25 W per channel. Actually the space by that IC is covered by a CD player which I removed to be able to see the board. So I'm guessing heat isn't a problem.

Do you get a reading from any of those eight "speaker" leads to the body of the automobile?

I would have to put the unit back together and stick it back into the auto. So what you want me to do is put all the wiring back to normal and then stick one of the VOM probes into a speaker output wire from the back of the stereo and touch the other probe to the car chassis - measuring Ohms or Voltage? Does it matter which probe goes where?

Also, if the amp is working properly, you'll have 6-7VDC from both speaker leads (at the speakers) to chassis GND.

I will have to take the door panel off to do this. Will try it tomorrow.

I did test the Ohm reading at the speaker when I did have the door off earlier and it read 4 Ohms, which is the speaker rating. Not sure if that tells anything.

Thanks for the help and appreciate the patience.

[kaboom]

Re: Help With Troubleshooting Car Stereo (Speaker) Problem

I would have to put the unit back together and stick it back into the auto. So what you want me to do is put all the wiring back to normal and then stick one of the VOM probes into a speaker output wire from the back of the stereo and touch the other probe to the car chassis - measuring Ohms or Voltage? Does it matter which probe goes where?

No. Check resistance to ground from the eight "SPKR" pins at the plug that goes to the radio.

[General_T]

Re: Help With Troubleshooting Car Stereo (Speaker) Problem

Hi Kaboom,

I will try that tomorrow.

Would you know what the pins marked B.UP and TM means?

[kaboom]

Re: Help With Troubleshooting Car Stereo (Speaker) Problem

Hi Kaboom,

I will try that tomorrow.

Would you know what the pins marked B.UP and TM means?

B.UP is likely fed from a constant 12V supply (hot w/ key off) for the clock and memory power.

TM may be a switched 12V or signal, active whenever the radio is on, for "power antenna" or "amplifier remote-turn-on" purposes. I can't tell for sure...

That tabbed device most certainly is a power IC. There's remnants of thermal compound.

[kaboom]

Re: Help With Troubleshooting Car Stereo (Speaker) Problem

I measured the outputs for the 4 speakers

You measure the pins on the board, didn't you?

All 4 speakers showed 122 ohms.

I think you measured this on the board, not by probing the wiring harness.

Get some clips and small wires that fit into the harness and measure the four pairs of speaker wires. Have the meter set for voltage first, in case you accidently transpose your connections! At least one of those pins has power at all times.

You want to measure the speakers, not the amp at this point. Ring out all four speaker ckts, right from the 14-pin plug.

[General_T]

Re: Help With Troubleshooting Car Stereo (Speaker) Problem

Hi Kaboom,

Yes, your right I checked the resistance on the PC Board vice the vehicle.

I did as you suggested and measured the resistance at the cables in the truck and as you were thinking there is an anomally.

3 of the 4 speakers measured 4 ohms but the suspect speaker (Front Left) measured around 2 million ohms. Is this a pretty good indicator that one or both of the wires are grounded out somewhere in the vehicle?

Thanks Again for this help.

PS. I also checked for voltage on that B.UP pin and it measured 12.75v as you guessed.

[kaboom]

Re: Help With Troubleshooting Car Stereo (Speaker) Problem

Hi Kaboom,

Yes, your right I checked the resistance on the PC Board vice the vehicle.

I did as you suggested and measured the resistance at the cables in the truck and as you were thinking there is an anomally.

3 of the 4 speakers measured 4 ohms but the suspect speaker (Front Left) measured around 2 million ohms. Is this a pretty good indicator that one or both of the wires are grounded out somewhere in the vehicle?

No, that's an open ckt, for all practical purposes. It'll certainly kill any audio to the left front speaker... Do either of the wires for the F-L measure anything to GND?

Thanks Again for this help.

You're welcome.

PS. I also checked for voltage on that B.UP pin and it measured 12.75v as you guessed.

I always like to have my meter set for voltage first whenever probing "unknowns." There are some meters today that will tolerate modest voltage when set to measure resistance, but that's generally still verboten. Always check for voltage first, it helps avoid any "kabooms."

[General_T]

Re: Help With Troubleshooting Car Stereo (Speaker) Problem

Hi Kaboom,

No, that's an open ckt, for all practical purposes. It'll certainly kill any audio to the left front speaker... Do either of the wires for the F-L measure anything to GND?

I checked the resistance to ground and the VOM showed "OL" which is either open line or infinite resistance - I'm guessing infinite resistance in this case. So is it possible the wire is cut somewhere and not shorted out?

I don't know how long I have been without this LF speaker - but it has been quite a while - I am a procrastinator. I recall awhile back (years) I had the transmission replaced (long story) and after it was replaced the remote car starter wouldn't work. The tech had cut a wire. I'm starting to wonder if this may be linked somehow?

[Th3_uN1Qu3]

Re: Help With Troubleshooting Car Stereo (Speaker) Problem

I checked the resistance to ground and the VOM showed "OL" which is either open line or infinite resistance - I'm guessing infinite resistance in this case. So is it possible the wire is cut somewhere and not shorted out?

Yes, exactly.

[kaboom]

Re: Help With Troubleshooting Car Stereo (Speaker) Problem

Hi Kaboom,



I checked the resistance to ground and the VOM showed "OL" which is either open line or infinite resistance - I'm guessing infinite resistance in this case. So is it possible the wire is cut somewhere and not shorted out?

I don't know how long I have been without this LF speaker - but it has been quite a while - I am a procrastinator. I recall awhile back (years) I had the transmission replaced (long story) and after it was replaced the remote car starter wouldn't work. The tech had cut a wire. I'm starting to wonder if this may be linked somehow?

Probably. Too many hacks out there...

Ok- do either of those LF wires, at the radio plug, have continuity to the speaker? I know both of them, combined, do not. Most likely, they're both broken.

Lots of wire flexing, every time the door is opened and closed. They probably broke right in that rubber "boot" that bridges the body to the door.

Yes, exactly.

Or even broken inside the insulation- not necessarily, visibly, "broken in two."

[General_T]

Re: Help With Troubleshooting Car Stereo (Speaker) Problem

So the next step is to start following the wires and hope it is relatively obvious. I will let you know what I find.

Thanks again for all this help!

[kaboom]

Re: Help With Troubleshooting Car Stereo (Speaker) Problem

So the next step is to start following the wires and hope it is relatively obvious. I will let you know what I find.

Thanks again for all this help!

Again, you're welcome!

[limcc]

Re: Help With Troubleshooting Car Stereo (Speaker) Problem

Hi,

Now what I would like to do is test the unit in my house but IOT do this I need to power the unit. I was thinking of using a 12v lawn tractor battery and was hoping for some instruction in how to do this safely.
[/LIST]

just FYI, if you have desktop PC, the molex connector will output +12V DC from yellow wire. Typical car audio head unit shouldn't draw more than 100W. or to be safe, remove all PSU connector from devices and short Green to any black ground wires on the ATX24 connector.