Distortion problem - Jeep Grand Cherokee & JVC KD-TD71BT head unit

[blueribb]

Okay I mis-read the 1st post that is on me.

Just use the jumpers then. The head units built in amplifier is only going to be maybe 20 watts if that. It isn't going to see that 50 watts they claim peak.

I would personally just dump the stock amplifier and go with a 4 channel aftermarket since you replaced speakers depending on the brand of speakers you used unless you went back to stock.

I would also run a separate ground from the head unit to a bolt in the area behind the head unit. I have done that multiple times with the Kenwood/JVC branded head units as they are the same company because of the issues you are talking about.

I used the existing ground wire that was connected to the factory radio. It worked perfectly for 6 months until the engine noise started. If the noise continues after eliminating the factory Infinity Amp, I will remove the new JVC head unit and reinstall the factory radio temporarily to see if the noise is still present.

 

[Firewalker]

Telling ya use another ground wire just to try or check the original one. Taking those dash covers is really easy on those at least. Kenwood/JVC have those issues. Used Kenwood/JVC head units for years as they are the same company. I had a '99 Grand Cherokee and put in a Kenwood Excelon KDC-X998 and used the existing ground wire. Within a couple weeks I had to do another one as it started to do what yours is doing and it stopped the distortion right away. Something to try doesn't take but a few minutes. Engine noise can happen at any time out of nowhere.

Agree with Mats above thinking it is a loose ground someplace. At least if you put the OEM radio back in all it takes is swapping out the harnesses since they just click into place. Should be really quick to do.

 

[blueribb]

Update: I managed to bypass the factory Infinity Amp using 2 jumpers. I only have the left rear speaker working but there is no distortion with the engine running. Before I condemn the old amp, I will use just the one speaker for a few days to make sure the distortion does not return. Then if I still can't find the Xscorpion Bypass kit, I will either re-cap the old amp or make permanent jumpers to bypass it.

 

[Firewalker]

I would just find a used one from a salvage yard or eBay for 50-60 bucks and replace it. A lot easier then trying to repair it.

http://rover.ebay.com/rover/1/711-5...0001&campid=5335951755&icep_item=402867344535

Check car-part.com for one in your area and price from salvage yards. It will be listed under amplifier/radio on the drop down menu for it. Will ask if it is a 4 channel or 6 channel as well. 4 channel comes right up with a ton of options from 20-65 dollars.

 

[hispls 5,000+ posts]

Update: I managed to bypass the factory Infinity Amp using 2 jumpers. I only have the left rear speaker working but there is no distortion with the engine running. Before I condemn the old amp, I will use just the one speaker for a few days to make sure the distortion does not return. Then if I still can't find the Xscorpion Bypass kit, I will either re-cap the old amp or make permanent jumpers to bypass it.

Unless you just enjoy troubleshooting antique electronics I wouldn't invest a minute into trying to repair the old factory amp, and trying to buy another 25 year old amp out of a boneyard probably isn't a long term fix either.

I wonder if you'll even notice the difference between that and the speaker level outputs from your modern JVC? If you really need more output just pick up a good quality aftermarket amplifier and you won't have to worry about that becoming the weak link for the remaining life of the vehicle (and possibly last the rest of your lifetime).

 

[blueribb]

Unless you just enjoy troubleshooting antique electronics I wouldn't invest a minute into trying to repair the old factory amp, and trying to buy another 25 year old amp out of a boneyard probably isn't a long term fix either.

I wonder if you'll even notice the difference between that and the speaker level outputs from your modern JVC? If you really need more output just pick up a good quality aftermarket amplifier and you won't have to worry about that becoming the weak link for the remaining life of the vehicle (and possibly last the rest of your lifetime).

Antique electronics ? ☺

I agree that buying a used amp isn't really a good idea. If the noise doesn't return in the next few days, I will most likely make my own amp bypass jumper. Recapping the old amp would have been a breeze years ago when I stocked electrolytics but I might pop the lid on the old amp just to take a peek. Domed electrolytics are pretty easy to spot and I still have my ESR meter.

 

[hispls 5,000+ posts]

Antique electronics ? ☺

I agree that buying a used amp isn't really a good idea. If the noise doesn't return in the next few days, I will most likely make my own amp bypass jumper. Recapping the old amp would have been a breeze years ago when I stocked electrolytics but I might pop the lid on the old amp just to take a peek. Domed electrolytics are pretty easy to spot and I still have my ESR meter.

When you consider the state of the art in modern 12V amp design, yeah, a factory DELCO amp is going to be extremely primitive. Then again, most of the stuff you'd get for cheap today is rather antiquated designs, but semiconductors have come a long way since the 90s.

Still, keep us posted on how this pans out.

 

[blueribb]

Yesterday I finished the Infinity Amp Bypass project. I chose insulated solid copper wire of the correct gauge to tightly fit inside the connector to the head unit. The jumpers won't fall out or short to each other. After tweaking all the JVC's sound settings, it sounds as good or better than the Infinity Amp. There is plenty of reserve power if I need it. I'm crossing my fingers the distortion doesn't return.

 

[hispls 5,000+ posts]

After tweaking all the JVC's sound settings, it sounds as good or better than the Infinity Amp.

I expected as much. Glad to hear that turned into a cheap fix anyway!

 

[blueribb]

Update: The distortion returned a couple days later. I called Crutchfield and they sent me a prepaid shipping label and will refund my full purchase price. They are completely out of stock of most JVC head units due to the chip shortage but I managed to find the same exact model listed on Amazon through a highly rated third party seller. They had 8 in stock when I placed the order. It will be here Saturday, so I'll make the swap over the weekend. I have my fingers crossed that this will fix the distortion issue. I will update this thread next week.

 

[hispls 5,000+ posts]

Update: The distortion returned a couple days later. I called Crutchfield and they sent me a prepaid shipping label and will refund my full purchase price. They are completely out of stock of most JVC head units due to the chip shortage but I managed to find the same exact model listed on Amazon through a highly rated third party seller. They had 8 in stock when I placed the order. It will be here Saturday, so I'll make the swap over the weekend. I have my fingers crossed that this will fix the distortion issue. I will update this thread next week.

Hope it's just the head unit, the only things left that would be not new would be the factory wires and speakers but none of what you described makes sense.

 

[blueribb]

Problem Fixed !

But, it wasn't the JVC head unit. After installing the replacement JVC, I noticed the front left door speaker had no sound. I jiggled all the jumpers I installed to bypass the Infinity Amp but still no sound. I banged on the drivers door and the sound returned. Today, I removed the door panel and removed the speaker. One wire fell out of the speaker terminal. Chrysler/Jeep used 18 gauge or thinner wire for the door speakers and the door speaker 's screw terminal just would not hold it in place tightly (Infinity Kappa 62.11i). After years of opening and closing the driver's door, the screw worked itself loose. I cut back the thin wires and stripped them. I had to use fine steel wool to make the copper wire shine since they were quite discolored. I bent the wire over to make it twice as thick, then applied a few drops of liquid flux. I used rosin core solder and my old trusty Weller Iron to tin them. They I used isopropyl alcohol to clean the flux off. After installing them in the speaker, they held really tight. I'm guessing my other 3 door speakers may need this treatment in the future.

The reason the distortion was only present when the engine was running was the vibration was causing the speaker connection to make and break.

Edit: In hindsight, I should have put my ear to every speaker when the distortion started, instead I thought it was all 4 speakers since I was so close to the driver's door speaker. Lesson learned.

Thanks to everyone that contributed.