2 Jl 500/1 amps one for parts one for repair

[tkowitha123]

I'm kinda new to repairing amps but I can follow instructions really good, haha but really I am kinda up to speed with automotive electronics, but I do need help.
Here's the thing I just acquired two non working 500/1 JL audio amps One amp has an Ohm's light that seems to stay on indefinately and the other turns on fine but doesn't seem to produce anything more than a barely audible 10 decibels from my sub (which is a brand new 15in JL W0V3 SVC 4Ohm) both amps worked in different cars less than a year ago and are in good physical shape so I'd like to fix both if possible or at least get on good working amp outta this.

 

[Perry Babin]

The one with the low impedance LED lit may have shorted output transistors.

With the black probe on the amp's ground terminal, what is the DC voltage on the positive and negative speaker terminals?

 

[tkowitha123]

ill have to go borrow a multimeter tomorrow since my doesnt seem to be in my toolbox and get back to you on that. I also at some point and time have to go pick up the amp with the Low OHM light on. The amp I'm more concerned about is the one that seems to power on fine but doesn't produce any real volume...no matter what amp settings, speaker config, or head unit???

 

[tkowitha123]

Another question will a rev 10 work in place of a rev 3?

 

[tkowitha123]

and also do I need power to the amp to check out dc voltage on my speaker terminals?

 

[Perry Babin]

For this thread, pick one amp and describe which one you choose in your next post in this thread. For the other amp, start another thread, listing the problems/symptoms for it.

Yes. The amp must be powered up normally when measuring the voltage on the speaker terminals.

 

[tkowitha123]

ok perry Were gonna stick with the low ohm light for this thread.

 

[tkowitha123]

I tested the speaker terminals to ground and found 76.4v on both positive and negitive from my understanding they should read around 40ish??? does that sound right and whats my next diagnoseing step?

 

[Perry Babin]

Are you sure that you checked one positive and one negative? It's strange that both are positive and that both are the same.

 

[tkowitha123]

yes I checked both it is dark outside and Its possible I missed the negitive, I'll go try this one more time

 

[tkowitha123]

well now the number's were fluctuating a little +56.4v on positive and +54.0v on negitive speaker???

 

[Perry Babin]

Earlier, I stated that it was strange that both were positive. That's wrong. Both will be positive, referenced to ground. They should both read about 40v DC. When there is a problem, one generally swings to near 80v and the other to near 0v. Are you sure that your meter is reading accurately? If the battery is low, it could read higher than the actual voltage.

 

[tkowitha123]

yes I'm useing a brand new multi meter for my tests so shouldnt be that

 

[tkowitha123]

I did replace the battery in my multi-meter. It didn't seem to change any of my prior readings taken though.

 

[Perry Babin]

What is the DC voltage on the center leg of D600?

 

[tkowitha123]

so perry Will you speak to me like I know nothing about this I just don't wanna screw this up. and from what I can tell the center leg reads 0 dc volts. do that seem right?

 

[tkowitha123]

ok Re-checked that d600 center leg now with new batteries in the multimeter and it reads 1.4 mv

 

[Perry Babin]

It should read approximately 80v.

Are you sure that you previously read 54v and not 54mv on the speaker terminals?

 

[tkowitha123]

Yeah at one time it was as high as 76v not mv but it never really went below 50 v either...I guess I had chalked it up to batterys in meter

 

[Perry Babin]

The voltage on the output transistors is determined, in part, by the voltage on D600. The voltage on the outputs cannot be higher than the voltage on the center leg of D600. Re-check to see where the error is.