Audio Systems: 91 lebaron conv. 3.0 radio/cassete player infinity system no equalizer, infinity system, salvage yard

Question
Have garbeled sound from all speakers with both radio and tape.Instl good like unit from salvage yard.same problem .disconnected each spkr individually .Nochange.Need help in further t/s to isolate prblm and correct same.Each spkr has two cond plug .have volt ohm meter.Where do i check ?What should readings be?

Answer
I need to know what the garbled sound sounds like!

But, guessing without further inspiration, I would first take a look at the speakers.  If they are all water damaged or age distorted they will produce a garbled type of sound. So, first, get a known good speaker and hang on one of the amp outputs and see if you can get good sound.  We must determine if the problem is EXTERNAL to the electronics or INTERNAL.  The external items are speakers and wiring.

Internal causes - which would make all channels sound garbled - are power supply problems and voltage regulator in the audio preamp stage of the unit.

Use your voltmeter to check the voltage feed to the main unit.  Make sure it is the same voltage as battery that feeds car system.

See if that gets you along the solution path.  Then let me know more.

C