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Topic: Any simple way to test Amplifier? (Read 1294 times) previous topic - next topic

Any simple way to test Amplifier?

I'm trying to save my original premium sound system although I'm starting to second guess my decision. The Equalizer power button was broken so I took that out and had it soldered on since I couldn't replace the switch. Speakers were crackling in the front doors so I ordered a set of Polk 6.5 db651s speakers, took the door panels off and installed them last night. I'm still getting crackling whenever I adjust the equalizer from front to rear but then it levels out and the speakers sound o.k. Rear and dash speakers sound good as well when I put my ear to them.
The main issue that I have now is that the system isn't loud enough, not nearly as loud as it was when new and working right. At full volume it's loud enough to hear but it should be uncomfortable at that volume. I took out the rear panel in the trunk and looked at the amplifier. The mounts were broken off the amp but other then that I didn't see any issue. There are no lights on it or any way that I can see to tell if it's working. I have a multi meter but wouldn't know where to check it out. Any thoughts on how to test the amp?
Any thoughts on why my system is so low?
Thanks: Charlie

Any simple way to test Amplifier?

Reply #1 –
Are you sure the EQ button was soldered on?  I remember my 87 had the EQ and when it wasn't on, it was like you describe.  As for your crackling, i'd bet you've got dirty pots.  Seems like I remember that there's a way to clean dirty pots, both rotary and sliders, but I can't recall the specifics.  There are lots of guys here that would know more about that than me, but maybe that gets you started.

Any simple way to test Amplifier?

Reply #2 –
Quote from: TheFoeYouKnow;411071
Are you sure the EQ button was soldered on?  I remember my 87 had the EQ and when it wasn't on, it was like you describe.  As for your crackling, i'd bet you've got dirty pots.  Seems like I remember that there's a way to clean dirty pots, both rotary and sliders, but I can't recall the specifics.  There are lots of guys here that would know more about that than me, but maybe that gets you started.

 As far as the Eq button, I took it to a local tech hoping to have the power switch replaced but it's no longer available. He had the EQ apart when we were talking and said he was going to solder the connections if he couldn't find the switch. Now the power switch is just on all the time and it is working. It turns on and off with the stereo power button.
The crackling is a minor issue to me but I can live with. It completely clears up once you change the balance or front back and only crackles while you're adjusting it. Once I have it set I won't be changing that much so I could live with it. The sound is fairly clear overall the issue is that it's just too low. I'm going to check some grounds tonight and see what happens if I disconnect the Eq. My thoughts were that perhaps the amp isn't kicking in enough but I don't know. Any ideas are appreciated.

Any simple way to test Amplifier?

Reply #3 –
With the system powered up, check for power at the amp on Orange/Lt Blue and also at Yellow/Black.  You can download my EVTM from the link in my sig, start working at page 217 (219 actual) once you establish that there is good power and ground, you can at that point almost condemn the unit as bad, but fear not, once it's blown up we can adapt a 4 channel aftermarket amp to take it's place and do a better job.
For the EQ, O/LB is main power, but for the amp it's only PWOn signal, Y/Bk is main power to the amp, but it runs through a filter that would need to be replaced with one capable of handling more power, or eliminated if you have one integrated into the replacement amp. You can get the amp input colors (and what they are) from page 216 and the amp speaker outs are: LF+ (O/LG), LF- (LB/W), RF+ (DG/O), RF- (W/LG), LR+ (PK/LG), LR- (PK/LB), RR+ (PK/LB), RR- (DG/O).  The rear colors can be confusing because the LR- is the same as the RR+ and the RR- is the same as the RF+.  I suggest following the wires, or using your ohm meter to tell the difference by measuring from the AMP to the rear speakers. Figure them out and loop or fork terminate the wires before attaching to the aftermarket amp.
Don't go crazy with a huge 4ch amp, 50Wx4 is as big as you want to go without completely changing out the wiring.  A 50Wx4ch amp will kick the shiznit out of a 50Wx4ch deck all day.

Any simple way to test Amplifier?

Reply #4 –
Before I went any further into the amp I thought I'd try your first suggestion and looked up cleaning potentiometers. I bought a can of electrical contact cleaner and lube at Radio Shack and took the face off the EQ and the stereo cleaning the volume, balance and left right slider. This did the trick, I have proper volume now and the new Polk speakers sound great. Now I'm on to adding an aux. jack for my Ipod and putting it back together.
Thanks for the help.