Audio Systems: aftermarket stereo works, no sound, 1986 toyota celica, pioneer deh 1700

Question
i'll clarify. There is a small pop sound that all the speakers make when the unit is plugged in. I will check out the amplifier in the dash also. If the amp in the head unit is bad, does this mean a new head unit is needed?
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Followup To

Question -
i have a 1986 toyota celica with a pioneer DEH-1700 stereo. I have had the stereo for about 8 months, and it has done the job. Starting last thursday the stereo had quit powering up. I went behind the stereo, tightened all the wires, and it worked. It worked for 2 days. Now, since saturday the stereo has powered up, but there is no sound. Except when the stereo is plugged in. The deck still shows a stereo reception and the cd player spins up and plays but with no sound. I have checked the wires behind to make sure they are all connected, and they are. What are some solutions to this problem i am having. I am leaving on a road trip in a couple days and would like sound without buying a new deck (if possible). I do not have an amp installed, and each speaker has its own wires that run to them. I know the speakers still work because i hear a connecting noise when i plug the deck in. i have checked my ground, and it is tightly fitted and secure.

Answer -
what do you mean by "there is no sound. Except when the stereo is plugged in" what's being pluged into what?
The 86 celica was available with a "premium" sound system in which there would be an amplifier under the dash or under the passenger seat.  If this went bad it would make the problem of the cd player looking like it's still working but no sound coming from the speakers.  this amp should be bypassed so that the amplifier in the head unit drives the speakers or an aftermarket amp should be installed.  I see you said "and each speaker has its own wires that run to them" so I figure that means you've run your own wires which should've bypassed this amplifier.  If so it is possible the amplifier portion of the head unit has gone bad.

Answer
Yah unfortunatly if the amp inside the HU has blown there isnt much you can do for it. As for the amp in the dash or under a seat it will be a little hard to tell what it is since it's just a blackbox type unit like all the other units in the car (computers, airbag controllers, etc)
good luck and please let me know how it goes.