Help with troubleshooting and repair please

[borahshadow]

Hi all I am new to this forum so I hope this is in the right spot.

I just recently replaced all of the speakers and the head unit in my truck. The next step was to install an amp and subwoofer. My dad had a JL audio 8w1 4 ohm and a clarion APA1100 amp that he was no longer using so he let me have them I got everything installed and working but soon found out that every once in a while the amp just wouldn't work. The power light came on and everything but it just didn't output anything. Turning off the car/stereo didn't fix it but some amount of time usually would (eg overnight.) This has gotten more frequent and it is very frustrating.
My voltages are good and my ground is solid I just can't figure it out. I used 8 gage wire and I bolted my ground to a piece of metal on the side of the vehicle after removing the paint.
The odd thing is that when it works it works perfectly fine and usually survives start up and shut down but then with no rhyme or reason the next time I start it up it just doesn't work.

I will go ahead and summarize the symptoms in a list in case I got a little long winded above

• Power light on
• Voltages good ~14 Batt ~12 remote
• Ground solid
• Subwoofer is fine
• Amp is usually cold or mildly warm (ie not thermal shutdown)
• Works for a period of time ~6-24 hours and dies on next startup
• fresh startup won't fix it. Time will fix it
• When it works it works perfectly
• No voltage on output when not working

It is possible that during the installation it could have gotten turned on with the speaker wires shorted but that should have just sent it into protect and then it should have been fine when the truck started the next time.

I would like to repair it as I am pretty good with a soldering iron and such but I need to figure out what is wrong first.

Thanks for your help

[Perry Babin]

Have you confirmed that the signal source is producing signal when the amp will not produce output?

Has the amp ever started/stopped producing output when you hit a bump?

Have you tried operating all of the switches and controls through their entire range to see if that makes the output cut in/out?

Have you tried a different speaker connected directly (short wires) to the speaker terminals (both A and B) when the amp won't produce output?

[borahshadow]

I had a local audio shop bench test my head unit to test it and I don't think they found anything wrong. I have also a couple of times connected my mp3 player via a 3.5mm>Rca cable to the amp and it still didn't work.

No it has not ever had any correlation with a bump. for that matter I'm not sure it has ever started or stopped while power is applied (truck on). I couple of times I think it might have started or stopped within the first 30 or so seconds of startup but I'm not positive on that.

I have tried messing with the switch that enables or disables the LP filter but that is it.

I think once I tried a different speaker but most of the time I just measure (both A and B) with my multimeter on ac voltage.

[Perry Babin]

Try the rest of the controls also.

Did you always read 0.0v AC on the speaker terminals when it failed to produce output?

Can you post a photo of the inside of the amp?

[borahshadow]

I'll try the rest of the controls tomorrow.

Yes It did always read 0v when it doesn't work.

It is still mounted in my truck but I will be removing it sometime this week because I found another used amp that I am going to replace it with. I can post a picture after I get it removed and replaced this week.

[borahshadow]

Well I tried the other controls and they didn't make a difference. I don't have a pic of the inside yet.

From what you know now what is your suspicion on what is wrong and if it is feasible to repair. That amp I was going to buy got sold out from under me so I need to know how hard to look and such so I can decide what I can spend.

[borahshadow]

ok well I got a picture but I also have some more info

I had an amp from a friend that I had up on my (ghetto) bench. My power supply was only giving it 10V-11V I had it working playing music through my old 6.5 inch speakers. (LP filter off) so I took it out to my truck and it didn't work either. I was playing around and I could read 2.5V (constant) from one of the channels but not the other. when the speaker was connected It still didn't do anything until I did something I probably shouldn't have. I put my multimeter on ohms and tried to measure the ohms between the -speaker terminal and the ground(-battery) terminal. and the sub started playing music. when I lifted the leads the music stopped.:S. I put my amp back in and tried the same thing with no luck so I switched it back again and I could not reproduce the behavior.

Hopefully this is not just more confusing. But anyway here is the photo