Ti500.4 problem during bench test

dedlyjedly · Post by **dedlyjedly** » Tue Aug 31, 2010 4:49 pm

I tested a newly purchased Ti500.4 yesterday and had a problem that I thought someone might be able to help me diagnose.

The main issue is in the left front channel. There is a constant high frequency whine that is emitted regardless of gain setting or any other adjustments. There is music output on the channel as well, but it is very quiet and difficult to hear given the volume of the noise. While testing the other channels I noticed that the left rear channel is louder than the right rear channel as well. Also when either of the left channels is presented a load the red led that's visible through the left window will immediately light up brighter.

Supposedly this amp was purchased directly from PG, but I can't imagine what I'm experiencing ever slipping through factory testing. Any ideas on what this could be? Or even, if it could have been a result of shipping damage?

The Golden One · Post by **The Golden One** » Tue Aug 31, 2010 5:15 pm

im not 100% sure on this but it could be a capacitor either in the signal section or the power supply i have a zpx2 that had some bad power supply caps because someone hooked it up wrong and messed them up. but i didnt know it for a long time and it would blow tweets and sometimes sqeal really loud at all volume levels i eventually found it to be the caps and replaced them and now it sounds the way it should.

Post by **Eric D** » Wed Sep 01, 2010 11:14 am

I wish I could help with this one, but I am pretty dumbfounded as to what is going on with it.

Is this happening while installed, or on a test bench?

dedlyjedly · Post by **dedlyjedly** » Wed Sep 01, 2010 11:57 am

It's on the bench.

Post by **stipud** » Wed Sep 01, 2010 12:07 pm

I would guess some sort of RCA/preamp/crossover issue, but just what, I have no idea...

dedlyjedly · Post by **dedlyjedly** » Wed Sep 01, 2010 1:04 pm

I was thinking the same thing. Also of note, the two crossover frequency potentiometers are extremely stiff. I know the Ti pots sort of suck, but I've never seen any like these! I was thinking maybe the daughter board had come loose in shipping and caused both of these issues. I want to crack it open, but the warranty void sticker is still intact, and I might have to get paypal to help me out with a refund and send this amp back. It sucks dealing with crap like this, especially because it's a pristine aluminum example I've been looking for a while!

Post by **stipud** » Wed Sep 01, 2010 1:23 pm

The amp is years out of warranty regardless, so who cares?

The Golden One · Post by **The Golden One** » Wed Sep 01, 2010 1:40 pm

if your intent on sending it back then this may not help but if you think there's still hope you could turn the frequency pots back and forth in a linear motion until the stiffness is gone and it turn's with the same effort when you turn it. then after that you could give it another go on the bench and maybe move the rca's a little and make sure it make's a good contact in the amp after that if it's still the same then it's internal so then it would be up to you what you want to do after that.

dedlyjedly · Post by **dedlyjedly** » Wed Sep 01, 2010 2:14 pm

Yeah, I wasn't thinking I could get it covered under warranty!

I was just concerned about keeping it in the exact condition I received it in should the need for a return arise. Fortunately, it seems that the seller is being very understanding and I should be able to take a closer look.

valeks1 · Post by **valeks1** » Wed Sep 01, 2010 2:17 pm

Can you check supply +/- 15 Volts? Also check RCA Ground to Amp Ground should be 100 Ohms.

dedlyjedly · Post by **dedlyjedly** » Thu Sep 02, 2010 9:07 pm

Resistance to ground is easy enough, and I know how to do DCV as well, but where would I probe exactly to test the power supply as you indicated?

valeks1 · Post by **valeks1** » Thu Sep 02, 2010 10:04 pm

On any OP Amp on Xover or main board pin4 and pin8 to ground

akwizeguy · Post by **akwizeguy** » Mon Sep 06, 2010 9:12 pm

Did you ever figure out the problem with this?
The weirdest thing happened today, I have a PG ZX475ti, I went to run some errands today, everything was running well. Parked the car, and came back out maybe 3 hours later, when my headunit booted up, there was that constant HIGH frequency squealing out. I moved the frequency pots back and forth, checked my RCAs and all, but still nothing. Tried shutting it down and turning it back on, but nothing happened. Anyone know what is the cause of this situation?

Post by **kg1961** » Tue Sep 07, 2010 5:33 am

As much as i love the zx/ti amp this is why I didn't want to use them this time around

dedlyjedly · Post by **dedlyjedly** » Tue Sep 07, 2010 6:11 pm

I haven't figured out what the problem is yet.

Is your problem affecting all of the channels? Is the noise present when there aren't any rca's connected to the amplifier? Have you tried another source like an ipod directly into the amplifier?

Post by **ttocs** » Tue Sep 07, 2010 8:17 pm

was it in the music/signal, or from the amp itself?

akwizeguy · Post by **akwizeguy** » Wed Sep 08, 2010 2:04 pm

dedlyjedly wrote:I haven't figured out what the problem is yet.

Is your problem affecting all of the channels? Is the noise present when there aren't any rca's connected to the amplifier? Have you tried another source like an ipod directly into the amplifier?

I only had the front channels connected, I never got around to hooking up the rear channels. I bought the zx475ti in 2008 from a forum member, so it is strange that this happened all of a sudden.

I haven't gotten around to troubleshooting the amp yet, with that damn tropical storm and all, and preparing for medical school interviews.

I did disconnect the RCAs from the amp, and tried running it and 5 minutes later, the tweets on my RSD65cs started to smoke, so it has to be from the amp itself. Ahh geez.....I really hope its not the amp, the RSDs are pretty inexpensive to replace, but the amp....man.....

rolandk · Post by **rolandk** » Fri Sep 10, 2010 12:29 pm

Try setting the amp crossover switches to bypass and see if the noise goes away.